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] Wire Nuts in Motor Junction Boxes?
Can anyone: -confirm that wire nuts are not allowed in induction motor junction boxes in the EU? -provide reasons why? -suggest solutions other than permanently mounted terminal strips? I'm not finding this in IEC 60204-1, but it seems to be a common practice that IEC motors have terminal strips rather than loose wire leads. Interestingly, clause 13.5.9.2 of NFPA 79 explicitly prohibits twist-on wire connectors for motor connection boxes. Thanks! Mike Sherman Product Safety Compliance Engineer Graco Inc. - 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] Wire Nuts in Motor Junction Boxes?
IIRC NFPA79 is almost a clone of 60204-1 :-)John AllenCompliance with ExperienceW.London. UKSent from my FonepadMike Sherman - Original Message - msherma...@comcast.net wrote:Can anyone: -confirm that wire nuts are not allowed in induction motor junction boxes in the EU? -provide reasons why? -suggest solutions other than permanently mounted terminal strips? I'm not finding this in IEC 60204-1, but it seems to be a common practicethat IEC motors have terminal strips rather than loose wire leads. Interestingly, clause 13.5.9.2 of NFPA 79 explicitly prohibits "twist-on wire connectors" for motor connection boxes. Thanks!Mike Sherman Product Safety Compliance Engineer Graco Inc. - 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] Wire Nuts in Motor Junction Boxes?
In message 1771936259.98100.1387233101354.javamail.r...@sz0110a.emeryville.ca.mail. comcast.net, dated Mon, 16 Dec 2013, Mike Sherman - Original Message - msherma...@comcast.net writes: -confirm that wire nuts are not allowed in induction motor junction boxes in the EU? -provide reasons why? -suggest solutions other than permanently mounted terminal strips? Europe has never been keen on wire nuts - indeed the term is regarded as transatlantic. In Britain, we used to have 'Scruits' - brand name, which were ceramic, but I'm 99% certain that they are not used now, although I don't recall a specific ban in BS 7671. Vibration could cause Scruits to 'unscrew' if they were not tightened fully, which may be why using them near motors is unwise. I suspect you could use 'chocolate block' located on pins rather than bolted down; I've seen this in a number of products. -- 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] Wire Nuts in Motor Junction Boxes?
PSNet, There was a lot of work in the US to harmonize IEC 60204 with NFPA 79 about a decade ago. Machine manufacturers are using NFPA 79 as a proxy for 60204 since their shops and suppliers understand the requirements expressed in this way. More power to them; I'd like to see US made machines bear a NFPA 79 field inspection sticker when shipped overseas to reinforce this idea. One set of requirements worldwide! - Here's a bumper sticker for machines. :) br, Pete Peter E Perkins, PE Principal Product Safety Engineer PO Box 23427 Tigard, ORe 97281-3427 503/452-1201 fone/fax p.perk...@ieee.org - 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
