Re: [PSES] Cooling fan safety query
Hello Rich; Can I suggest to the safety testing agency to disconnect or stall the fan rotor for all testing? Would this then mean the CFM rating for the cooling fan would not be required? Regards; Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com From: Richard Nute [mailto:ri...@ieee.org] Sent: 13 December 2013 20:06 To: McBurney, Ian; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query Hello Ian: The first question is whether or not the fan is necessary to meet the temperature requirements of the standard. If yes, then the fan and its alternates must be tested to prove that the end-product meets the temperature requirements. A UL-certified fan should reduce the testing requirements. The fact that you put a resistor in series with the motor does not affect this requirement. However, in stalled rotor condition, the resistor must not exceed its power rating. The CFM rating of the fan is not applicable with a resistor in series with the fan. So, if meeting temperature requirements with the fan, it would be necessary to meet temperature requirements with each different fan (because the CFM cannot be predicted with a resistor in series). Model numbers of tested fans would be required, although I don't know why the CFM rating of each fan would be required since compliance with the temperature requirements would not be dependent on the CFM rating. If no, then the fan can be removed (or disconnected) and the end-product should meet all the applicable safety requirements, including the temperature requirements. Under this condition, the fan is just another functional component. Ask the cert house to perform all testing without the fan. However, the fans should meet the stalled rotor requirements and, if applicable, the plastic flame rating requirements. These should be a part of the UL certification. Also, the series resistor must be rated for the power dissipation in the stalled rotor condition. This may require testing each alternate fan; if so, each different fan must be identified. With best wishes for the holiday season, Rich On 12/13/2013 2:02 AM, McBurney, Ian wrote: This is a question for the safety testing engineers. We have products that contain 12V/24V DC cooling fans that cool either the PSU or processing circuits. The fan speeds are reduced with basically a series resistor to reduce audio noise. The safety testing agency demands to know the exact model number and CFM of each fan even though the products continue to function during the stalled rotor test. Obviously there is temperature rise within the product. My question is why does the agency list the exact model number and CFM rating of the fan even though it doesn't run at full speed and the product continues to function with a stalled rotor. We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won't accept a manufacturers range of fans without testing each one. All fans used are UL listed and the products are tested to IEC/UL 60065. Your comments would be appreciated. Many thanks in advance. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.commailto:ian.mcbur...@allen-heath.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
Hello Ian: In my opinion, if you stalled the fan for all testing, there would be no reason to require the CFM rating. Stalling the fan would be the better course of action as this would require the fan motor to dissipate some power as well as the series resistor, thus causing more heat -- but not much -- in the equipment. Best wishes for the holiday season, Richard Nute Product Safety Consultant Bend, Oregon, U.S.A. On 12/16/2013 1:30 AM, McBurney, Ian wrote: Hello Rich; Can I suggest to the safety testing agency to disconnect or stall the fan rotor for all testing? Would this then mean the CFM rating for the cooling fan would not be required? Regards; Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com *From:*Richard Nute [mailto:ri...@ieee.org] *Sent:* 13 December 2013 20:06 *To:* McBurney, Ian; EMC-PSTC@LISTSERV.IEEE.ORG *Subject:* Re: [PSES] Cooling fan safety query Hello Ian: The first question is whether or not the fan is necessary to meet the temperature requirements of the standard. If yes, then the fan and its alternates must be tested to prove that the end-product meets the temperature requirements. A UL-certified fan should reduce the testing requirements. The fact that you put a resistor in series with the motor does not affect this requirement. However, in stalled rotor condition, the resistor must not exceed its power rating. The CFM rating of the fan is not applicable with a resistor in series with the fan. So, if meeting temperature requirements with the fan, it would be necessary to meet temperature requirements with each different fan (because the CFM cannot be predicted with a resistor in series). Model numbers of tested fans would be required, although I don't know why the CFM rating of each fan would be required since compliance with the temperature requirements would not be dependent on the CFM rating. If no, then the fan can be removed (or disconnected) and the end-product should meet all the applicable safety requirements, including the temperature requirements. Under this condition, the fan is just another functional component. Ask the cert house to perform all testing without the fan. However, the fans should meet the stalled rotor requirements and, if applicable, the plastic flame rating requirements. These should be a part of the UL certification. Also, the series resistor must be rated for the power dissipation in the stalled rotor condition. This may require testing each alternate fan; if so, each different fan must be identified. With best wishes for the holiday season, Rich On 12/13/2013 2:02 AM, McBurney, Ian wrote: This is a question for the safety testing engineers. We have products that contain 12V/24V DC cooling fans that cool either the PSU or processing circuits. The fan speeds are reduced with basically a series resistor to reduce audio noise. The safety testing agency demands to know the exact model number and CFM of each fan even though the products continue to function during the stalled rotor test. Obviously there is temperature rise within the product. My question is why does the agency list the exact model number and CFM rating of the fan even though it doesn't run at full speed and the product continues to function with a stalled rotor. We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won't accept a manufacturers range of fans without testing each one. All fans used are UL listed and the products are tested to IEC/UL 60065. Your comments would be appreciated. Many thanks in advance. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com mailto:ian.mcbur...@allen-heath.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
From: Richard Nute Sent: Monday, December 16, 2013 11:03 Stalling the fan would be the better course of action as this would require the fan motor to dissipate some power as well as the series resistor, thus causing more heat -- but not much -- in the equipment. My experience with small impulse start fans is that that generate negligible heat when stalled, but this method would remove all doubt. Peter Tarver This email message is for the sole use of the intended recipient(s) and may contain confidential and/or privileged information. If you are not an intended recipient, you may not review, use, copy, disclose or distribute this message. If you received this message in error, please contact the sender by reply email and destroy all copies of the original message. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
Stalling would like be required by the agency anyway since a typical failure is a jam or bearing failure that would lock the rotor. Gary From: Richard Nute [mailto:ri...@ieee.org] Sent: Monday, December 16, 2013 11:03 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query Hello Ian: In my opinion, if you stalled the fan for all testing, there would be no reason to require the CFM rating. Stalling the fan would be the better course of action as this would require the fan motor to dissipate some power as well as the series resistor, thus causing more heat -- but not much -- in the equipment. Best wishes for the holiday season, Richard Nute Product Safety Consultant Bend, Oregon, U.S.A. On 12/16/2013 1:30 AM, McBurney, Ian wrote: Hello Rich; Can I suggest to the safety testing agency to disconnect or stall the fan rotor for all testing? Would this then mean the CFM rating for the cooling fan would not be required? Regards; Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.commailto:ian.mcbur...@allen-heath.com From: Richard Nute [mailto:ri...@ieee.org] Sent: 13 December 2013 20:06 To: McBurney, Ian; EMC-PSTC@LISTSERV.IEEE.ORGmailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query Hello Ian: The first question is whether or not the fan is necessary to meet the temperature requirements of the standard. If yes, then the fan and its alternates must be tested to prove that the end-product meets the temperature requirements. A UL-certified fan should reduce the testing requirements. The fact that you put a resistor in series with the motor does not affect this requirement. However, in stalled rotor condition, the resistor must not exceed its power rating. The CFM rating of the fan is not applicable with a resistor in series with the fan. So, if meeting temperature requirements with the fan, it would be necessary to meet temperature requirements with each different fan (because the CFM cannot be predicted with a resistor in series). Model numbers of tested fans would be required, although I don't know why the CFM rating of each fan would be required since compliance with the temperature requirements would not be dependent on the CFM rating. If no, then the fan can be removed (or disconnected) and the end-product should meet all the applicable safety requirements, including the temperature requirements. Under this condition, the fan is just another functional component. Ask the cert house to perform all testing without the fan. However, the fans should meet the stalled rotor requirements and, if applicable, the plastic flame rating requirements. These should be a part of the UL certification. Also, the series resistor must be rated for the power dissipation in the stalled rotor condition. This may require testing each alternate fan; if so, each different fan must be identified. With best wishes for the holiday season, Rich On 12/13/2013 2:02 AM, McBurney, Ian wrote: This is a question for the safety testing engineers. We have products that contain 12V/24V DC cooling fans that cool either the PSU or processing circuits. The fan speeds are reduced with basically a series resistor to reduce audio noise. The safety testing agency demands to know the exact model number and CFM of each fan even though the products continue to function during the stalled rotor test. Obviously there is temperature rise within the product. My question is why does the agency list the exact model number and CFM rating of the fan even though it doesn't run at full speed and the product continues to function with a stalled rotor. We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won't accept a manufacturers range of fans without testing each one. All fans used are UL listed and the products are tested to IEC/UL 60065. Your comments would be appreciated. Many thanks in advance. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.commailto:ian.mcbur...@allen-heath.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.orgmailto:emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)http://www.ieee-pses.org/list.html List rules
[PSES] Cooling fan safety query
This is a question for the safety testing engineers. We have products that contain 12V/24V DC cooling fans that cool either the PSU or processing circuits. The fan speeds are reduced with basically a series resistor to reduce audio noise. The safety testing agency demands to know the exact model number and CFM of each fan even though the products continue to function during the stalled rotor test. Obviously there is temperature rise within the product. My question is why does the agency list the exact model number and CFM rating of the fan even though it doesn't run at full speed and the product continues to function with a stalled rotor. We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won't accept a manufacturers range of fans without testing each one. All fans used are UL listed and the products are tested to IEC/UL 60065. Your comments would be appreciated. Many thanks in advance. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
In message 80f690de07894e049b221728b4a99...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won?t accept a manufacturers range of fans without testing each one. On what grounds are they re-testing when the fans are UL-listed? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
John; I believe the fans are listed for the flammability of the plastic body but I may be wrong. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 13 December 2013 10:34 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query In message 80f690de07894e049b221728b4a99...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won?t accept a manufacturers range of fans without testing each one. On what grounds are they re-testing when the fans are UL-listed? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
In message ed08bb5be2d841e0a1b0ca499f924...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: I believe the fans are listed for the flammability of the plastic body but I may be wrong. It would surely be worthwhile to check whether UL have confirmed electrical safety, because if not, the test house is probably justified. So you would need to list all the fans that could be used, or find a less exacting test house. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
Hi Ian, The last company I was with used to specify a single manufacturer's fan in the UL report including supply voltage / current / CFM) and then (with UL's agreement) include the words or any recognised equivalent component. During the factory inspections, if a fan was being fitted from a different manufacturer we would have to produce the fan specification to show that we met the requirements i.e. the fan was UL recognised, supply voltage was the same, current was equal to or less than specified in the report and the CFM was equal to or greater than specified. Thanks, Chris. -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 13 December 2013 11:23 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query In message ed08bb5be2d841e0a1b0ca499f924...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: I believe the fans are listed for the flammability of the plastic body but I may be wrong. It would surely be worthwhile to check whether UL have confirmed electrical safety, because if not, the test house is probably justified. So you would need to list all the fans that could be used, or find a less exacting test house. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
Ian I think the critical factor may be the airflow rates at the reduced voltages as this may well vary between various ostensibly similar fans of the same nominal voltage. The actual airflow patterns from the outputs of the various fans may also differ due to differing blade profiles, etc. Regards John Allen Compliance with Experience W.London. UK -Original Message- From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] Sent: 13 December 2013 11:05 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query John; I believe the fans are listed for the flammability of the plastic body but I may be wrong. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 13 December 2013 10:34 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query In message 80f690de07894e049b221728b4a99...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won?t accept a manufacturers range of fans without testing each one. On what grounds are they re-testing when the fans are UL-listed? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3658/6909 - Release Date: 12/10/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3658/6909 - Release Date: 12/10/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3658/6916 - Release Date: 12/13/13 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
John; I agree the airflow rates will vary with applied voltage and blade profile but if the product continues to function safely with a stalled rotor why does it have to be listed in the critical component list. Regards; Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: 13 December 2013 13:31 To: McBurney, Ian; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Cooling fan safety query Ian I think the critical factor may be the airflow rates at the reduced voltages as this may well vary between various ostensibly similar fans of the same nominal voltage. The actual airflow patterns from the outputs of the various fans may also differ due to differing blade profiles, etc. Regards John Allen Compliance with Experience W.London. UK -Original Message- From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] Sent: 13 December 2013 11:05 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query John; I believe the fans are listed for the flammability of the plastic body but I may be wrong. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 13 December 2013 10:34 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query In message 80f690de07894e049b221728b4a99...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won?t accept a manufacturers range of fans without testing each one. On what grounds are they re-testing when the fans are UL-listed? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3658/6909 - Release Date: 12/10/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3658/6909 - Release Date: 12/10/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3658/6916 - Release Date: 12/13/13 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http
Re: [PSES] Cooling fan safety query
Ian That's a very good question! The only other things that I can currently think of are: - The agency does not (want to?) accept the UL Recognition (not Listing, I suspect) for business political reasons because UL is a competitor (and AFAIK, there is no compelling legal reason why they have to where components and materials are concerned - but it's common business practice to do for the sake of relationships with their own customers), - /or either the project engineer or his senior engineer are playing very safe and don't want to trust anything they think they can't be 150% sure of (and some agency engineers don't have too much experience of dealing with design approaches which are not exactly in line with what the standard appears to mandate!. They are also bound by the defined operating procedures of their agency, and this can be very frustrating in its own right - like others here, I know because I have been there :-( ) Either way, have you tried getting a clear explanation from the agency as to exactly why they are requiring this extra testing? Regards John Allen Compliance with Experience W.London, UK. -Original Message- From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] Sent: 13 December 2013 13:55 To: John Allen; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Cooling fan safety query John; I agree the airflow rates will vary with applied voltage and blade profile but if the product continues to function safely with a stalled rotor why does it have to be listed in the critical component list. Regards; Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: 13 December 2013 13:31 To: McBurney, Ian; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Cooling fan safety query Ian I think the critical factor may be the airflow rates at the reduced voltages as this may well vary between various ostensibly similar fans of the same nominal voltage. The actual airflow patterns from the outputs of the various fans may also differ due to differing blade profiles, etc. Regards John Allen Compliance with Experience W.London. UK -Original Message- From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] Sent: 13 December 2013 11:05 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query John; I believe the fans are listed for the flammability of the plastic body but I may be wrong. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 13 December 2013 10:34 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query In message 80f690de07894e049b221728b4a99...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won?t accept a manufacturers range of fans without testing each one. On what grounds are they re-testing when the fans are UL-listed? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee
Re: [PSES] Cooling fan safety query
In message ff0018ae2af54a2b95bfa760f8747...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: but if the product continues to function safely with a stalled rotor why does it have to be listed in the critical component list. Why does the test house say it does? They have to justify their opinions. We can only guess, and even if we guess right, you are no further forward. You have to get their reason, in their words, and refute it. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
John; I have often asked for the reasoning to many similar problems and get directed to an ambiguous clause in the standard that I read one way and the agency reads the other way and because there is no independent arbiter I end up acquiescing as the whole process slows down and I am on a tight deadline to market. regards Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 13 December 2013 14:18 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query In message ff0018ae2af54a2b95bfa760f8747...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: but if the product continues to function safely with a stalled rotor why does it have to be listed in the critical component list. Why does the test house say it does? They have to justify their opinions. We can only guess, and even if we guess right, you are no further forward. You have to get their reason, in their words, and refute it. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
A locked rotor test is considered an abnormal and measured temperatures are allowed to exceed the limits for normal operation. If that happens, then it proves a minimal amount of airflow is required to maintain safe temperatures and minimal CFMs become required. That said, I've never seen a CPU fan be the make or break for safe temperatures (except maybe a laptop). It is likely you have a (written or unwritten) standard operating procedure that states what must be called out for fans and an engineer that is either unwilling or unable to justify removing the requirement. After all, it is hard to find a regulatory engineer that can do both. -Will William L Brown Jr. / Engineering Manager - Regulatory and Compliance / Tyco Security Products Tel: +1 978 577 4205 / Mobile: +1 978 727 7069 6 Technology Park Drive / Westford, MA 01886 / USA willbr...@tycoint.com / www.tycosecurityproducts.com/SocialMedia.aspx / www.tycosecurityproducts.com Access Control, Video, Location-Based Tracking and Intrusion. UNIFIED. CONFIDENTIALITY NOTICE: This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information or information otherwise protected by law. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. Any applicable rights to privilege have not been waived. . -Original Message- From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] Sent: Friday, December 13, 2013 8:55 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query John; I agree the airflow rates will vary with applied voltage and blade profile but if the product continues to function safely with a stalled rotor why does it have to be listed in the critical component list. Regards; Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: 13 December 2013 13:31 To: McBurney, Ian; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Cooling fan safety query Ian I think the critical factor may be the airflow rates at the reduced voltages as this may well vary between various ostensibly similar fans of the same nominal voltage. The actual airflow patterns from the outputs of the various fans may also differ due to differing blade profiles, etc. Regards John Allen Compliance with Experience W.London. UK -Original Message- From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] Sent: 13 December 2013 11:05 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query John; I believe the fans are listed for the flammability of the plastic body but I may be wrong. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 13 December 2013 10:34 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query In message 80f690de07894e049b221728b4a99...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won?t accept a manufacturers range of fans without testing each one. On what grounds are they re-testing when the fans are UL-listed? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message
Re: [PSES] Cooling fan safety query
In message c8225bb6612e4cf382ba4b073e71d...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: I have often asked for the reasoning to many similar problems and get directed to an ambiguous clause in the standard that I read one way and the agency reads the other way and because there is no independent arbiter You have to deal case-by-case; you may not win all arguments but you can win some. ***But there IS an arbiter***; the originating committee and that may well be accessible via members of this list. So ask the crucial question! -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
Agreed on both counts! John Allen Sent from my Fonepad "Brown,William" <willbr...@tycoint.com> wrote:>A locked rotor test is considered an abnormal and measured temperatures are allowed to exceed the limits for normal operation. If that happens, then it proves a minimal amount of airflow is required to maintain safe temperatures and minimal CFMs become required. > >That said, I've never seen a CPU fan be the make or break for safe temperatures (except maybe a laptop). It is likely you have a (written or unwritten) standard operating procedure that states what must be called out for fans and an engineer that is either unwilling or unable to justify removing the requirement. > >After all, it is hard to find a regulatory engineer that can do both. > >-Will > >William L Brown Jr. / Engineering Manager - Regulatory and Compliance / Tyco Security Products >Tel: +1 978 577 4205 / Mobile: +1 978 727 7069 > >6 Technology Park Drive / Westford, MA 01886 / USA >willbr...@tycoint.com / www.tycosecurityproducts.com/SocialMedia.aspx / www.tycosecurityproducts.com > > >Access Control, Video, Location-Based Tracking and Intrusion. UNIFIED. > >CONFIDENTIALITY NOTICE: This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information or information otherwise protected by law. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. Any applicable rights to privilege have not been waived. >. > >-Original Message- >From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] >Sent: Friday, December 13, 2013 8:55 AM >To: EMC-PSTC@LISTSERV.IEEE.ORG >Subject: Re: [PSES] Cooling fan safety query > >John; > >I agree the airflow rates will vary with applied voltage and blade profile but if the product continues to function "safely" with a stalled rotor why does it have to be listed in the critical component list. > >Regards; > >Ian McBurney >Design & Compliance Engineer. > >Allen & Heath Ltd. >Kernick Industrial Estate, >Penryn, Cornwall. TR10 9LU. UK >T: 01326 372070 >E: ian.mcbur...@allen-heath.com > > > >-Original Message----- >From: John Allen [mailto:john_e_al...@blueyonder.co.uk] >Sent: 13 December 2013 13:31 >To: McBurney, Ian; EMC-PSTC@LISTSERV.IEEE.ORG >Subject: RE: [PSES] Cooling fan safety query > >Ian > >I think the critical factor may be the airflow rates at the reduced voltages as this may well vary between various ostensibly similar fans of the same nominal voltage. > >The actual airflow patterns from the outputs of the various fans may also differ due to differing blade profiles, etc. > >Regards > >John Allen >Compliance with Experience >W.London. UK > >-Original Message- >From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] >Sent: 13 December 2013 11:05 >To: EMC-PSTC@LISTSERV.IEEE.ORG >Subject: Re: [PSES] Cooling fan safety query > >John; > >I believe the fans are listed for the flammability of the plastic body but I may be wrong. > >Ian McBurney >Design & Compliance Engineer. > >Allen & Heath Ltd. >Kernick Industrial Estate, >Penryn, Cornwall. TR10 9LU. UK >T: 01326 372070 >E: ian.mcbur...@allen-heath.com > > >-Original Message- >From: John Woodgate [mailto:j...@jmwa.demon.co.uk] >Sent: 13 December 2013 10:34 >To: EMC-PSTC@LISTSERV.IEEE.ORG >Subject: Re: [PSES] Cooling fan safety query > >In message ><80f690de07894e049b221728b4a99...@dbxpr07mb206.eurprd07.prod.outlook.com> >, dated Fri, 13 Dec 2013, "McBurney, Ian" <ian.mcbur...@allen-heath.com> >writes: > >>We have to use alternative fans due to supply issues and this incurs >>considerable test agency costs as the agency won?t accept a >>manufacturers range of fans without testing each one. > >On what grounds are they re-testing when the fans are UL-listed? >-- >OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK > >- > >This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> > >All emc-pstc postings are archived and searchable on the web at: >http://www.ieee-pses.org/emc-pstc.html > >Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics
Re: [PSES] [External] Re: [PSES] Cooling fan safety query
Additionally, most agencies have a process to repeal or elevate a decision beyond the engineer that you are directly working with. Josh -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, December 13, 2013 8:53 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [External] Re: [PSES] Cooling fan safety query In message c8225bb6612e4cf382ba4b073e71d...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: I have often asked for the reasoning to many similar problems and get directed to an ambiguous clause in the standard that I read one way and the agency reads the other way and because there is no independent arbiter You have to deal case-by-case; you may not win all arguments but you can win some. ***But there IS an arbiter***; the originating committee and that may well be accessible via members of this list. So ask the crucial question! -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
Will is correct. I have gotten around this type of fan issue in the past by simply running the normal heating test with the fan disconnected. If you can pass normal temperature rise limits without the fan then your argument becomes easier as the fan is no longer critical, it is simply a design robustness feature at that point. For the device to operate normally and to operate within the limits are not always the same. Josh -Original Message- From: Brown,William [mailto:willbr...@tycoint.com] Sent: Friday, December 13, 2013 8:52 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [External] Re: [PSES] Cooling fan safety query A locked rotor test is considered an abnormal and measured temperatures are allowed to exceed the limits for normal operation. If that happens, then it proves a minimal amount of airflow is required to maintain safe temperatures and minimal CFMs become required. That said, I've never seen a CPU fan be the make or break for safe temperatures (except maybe a laptop). It is likely you have a (written or unwritten) standard operating procedure that states what must be called out for fans and an engineer that is either unwilling or unable to justify removing the requirement. After all, it is hard to find a regulatory engineer that can do both. -Will William L Brown Jr. / Engineering Manager - Regulatory and Compliance / Tyco Security Products Tel: +1 978 577 4205 / Mobile: +1 978 727 7069 6 Technology Park Drive / Westford, MA 01886 / USA willbr...@tycoint.com / www.tycosecurityproducts.com/SocialMedia.aspx / www.tycosecurityproducts.com Access Control, Video, Location-Based Tracking and Intrusion. UNIFIED. CONFIDENTIALITY NOTICE: This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information or information otherwise protected by law. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. Any applicable rights to privilege have not been waived. . -Original Message- From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] Sent: Friday, December 13, 2013 8:55 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query John; I agree the airflow rates will vary with applied voltage and blade profile but if the product continues to function safely with a stalled rotor why does it have to be listed in the critical component list. Regards; Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: 13 December 2013 13:31 To: McBurney, Ian; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Cooling fan safety query Ian I think the critical factor may be the airflow rates at the reduced voltages as this may well vary between various ostensibly similar fans of the same nominal voltage. The actual airflow patterns from the outputs of the various fans may also differ due to differing blade profiles, etc. Regards John Allen Compliance with Experience W.London. UK -Original Message- From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] Sent: 13 December 2013 11:05 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query John; I believe the fans are listed for the flammability of the plastic body but I may be wrong. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 13 December 2013 10:34 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query In message 80f690de07894e049b221728b4a99...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won?t accept a manufacturers range of fans without testing each one. On what grounds are they re-testing when the fans are UL-listed? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product
Re: [PSES] Cooling fan safety query
Ian It doesn't function safely with the stalled rotor, it functions not dangerously. In fact the standard doesn't really care whether it functions, just whether it's unsafe. Do you need the fans to meet maximum temperature limits in normal operation, or just to lower temperatures and prolong component life? If you need a certain CFM to ensure that temperature limits for normal operation are met, then you will need to have one or more fans listed as critical components. But if you don't, then there shouldn't be an issue with whatever fan you use. Also, since you have variable speed fans, how is the temperature test being done - at ambient with deltas or in a thermal chamber? Regards Charlie -Original Message- From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] Sent: 13 December 2013 13:55 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query John; I agree the airflow rates will vary with applied voltage and blade profile but if the product continues to function safely with a stalled rotor why does it have to be listed in the critical component list. Regards; Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: 13 December 2013 13:31 To: McBurney, Ian; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Cooling fan safety query Ian I think the critical factor may be the airflow rates at the reduced voltages as this may well vary between various ostensibly similar fans of the same nominal voltage. The actual airflow patterns from the outputs of the various fans may also differ due to differing blade profiles, etc. Regards John Allen Compliance with Experience W.London. UK -Original Message- From: McBurney, Ian [mailto:ian.mcbur...@allen-heath.com] Sent: 13 December 2013 11:05 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query John; I believe the fans are listed for the flammability of the plastic body but I may be wrong. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 13 December 2013 10:34 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Cooling fan safety query In message 80f690de07894e049b221728b4a99...@dbxpr07mb206.eurprd07.prod.outlook.com , dated Fri, 13 Dec 2013, McBurney, Ian ian.mcbur...@allen-heath.com writes: We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won?t accept a manufacturers range of fans without testing each one. On what grounds are they re-testing when the fans are UL-listed? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database
Re: [PSES] Cooling fan safety query
Ian - Another consideration, since you have more than one fan, is that you can disable *all* fans simultaneously to demonstrate that no cooling is necessary for safety reasons. This is a multiple fault scenario, but it's at your discretion to do so to prove your case and eliminates the need for cfm ratings. Stalled rotor testing should not be needed in the end product unless: 1) the test was not done on the fan when it was safety certified (very common, even among UL Recognized fans) 2) the fan if it is not safety certified at all (you state the fans you're using are UL Listed, but I think you mean UL Recognized) 3) the fan is a type whose motor current under stalled conditions can overload another component of the power supply (the impulse start dc motors I've tested can go an interminably long time without getting more than a smidgeon above the local ambient temperature) Disabling (removing power) serves most of the thermal concerns. There are flammability issues that may need to be met, as mentioned by another poster, and providing the manufacturer and model can provide a level of traceability to the relevant materials. If you can successfully eliminate the need for cfm ratings and stalled rotor testing, your only concerns are reduced to flammability and loading of the power supply. In some cases, you can use the fan ratings alone to meet the standard's and certifier's requirements. As a final word, alternate or substitution of components is an ongoing issue for everyone involved in product safety certifications. You can try to have a handful of alternates ready when the certification evaluation is performed and still have this concern because there's always a less expensive alternative available. Peter Tarver This email message is for the sole use of the intended recipient(s) and may contain confidential and/or privileged information. If you are not an intended recipient, you may not review, use, copy, disclose or distribute this message. If you received this message in error, please contact the sender by reply email and destroy all copies of the original message. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] Cooling fan safety query
Hello Ian: The first question is whether or not the fan is necessary to meet the temperature requirements of the standard. If yes, then the fan and its alternates must be tested to prove that the end-product meets the temperature requirements. A UL-certified fan should reduce the testing requirements. The fact that you put a resistor in series with the motor does not affect this requirement. However, in stalled rotor condition, the resistor must not exceed its power rating. The CFM rating of the fan is not applicable with a resistor in series with the fan. So, if meeting temperature requirements with the fan, it would be necessary to meet temperature requirements with each different fan (because the CFM cannot be predicted with a resistor in series). Model numbers of tested fans would be required, although I don't know why the CFM rating of each fan would be required since compliance with the temperature requirements would not be dependent on the CFM rating. If no, then the fan can be removed (or disconnected) and the end-product should meet all the applicable safety requirements, including the temperature requirements. Under this condition, the fan is just another functional component. Ask the cert house to perform all testing without the fan. However, the fans should meet the stalled rotor requirements and, if applicable, the plastic flame rating requirements. These should be a part of the UL certification. Also, the series resistor must be rated for the power dissipation in the stalled rotor condition. This may require testing each alternate fan; if so, each different fan must be identified. With best wishes for the holiday season, Rich On 12/13/2013 2:02 AM, McBurney, Ian wrote: This is a question for the safety testing engineers. We have products that contain 12V/24V DC cooling fans that cool either the PSU or processing circuits. The fan speeds are reduced with basically a series resistor to reduce audio noise. The safety testing agency demands to know the exact model number and CFM of each fan even though the products continue to function during the stalled rotor test. Obviously there is temperature rise within the product. My question is why does the agency list the exact model number and CFM rating of the fan even though it doesn't run at full speed and the product continues to function with a stalled rotor. We have to use alternative fans due to supply issues and this incurs considerable test agency costs as the agency won't accept a manufacturers range of fans without testing each one. All fans used are UL listed and the products are tested to IEC/UL 60065. Your comments would be appreciated. Many thanks in advance. Ian McBurney Design Compliance Engineer. Allen Heath Ltd. Kernick Industrial Estate, Penryn, Cornwall. TR10 9LU. UK T: 01326 372070 E: ian.mcbur...@allen-heath.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
