Re: 3-Phase Power Question
Lou, Thanks for the information, we ran across this in an old building located in Santa Clara, California. There was no transformer located outside the building, just the drop lines from the power pole. The transformer may be located inside the main distribution panel in the electrical room, however we did not want to open any panels to look for it. Regards, Richard At 10:04 PM 6/5/03 -0500, you wrote: >Richard, I recognize that system. > >It is a 3 phase delta with one of the sides tapped in the middle for the >neutral. I haven't seen one since the late 50's, and then only in the >oldest sections of downtown Houston. The scheme provided 3 phase service to >AC compressors and air handlers, and also supplied 110 volts for lighting >and office equipment. > >The 208 phase you found was then known as the "wild phase" or the "stinger >leg". It was about 190 volts when the phase to phase voltage was 220. The >relationship to 240 does work out; 190 X (240/220) = 207; nearly what you >found. > >If you look outside the building you should be able to see the transformer >connections to confirm this. > >I had almost forgotten such a thing ever existed. > > >Lou Aiken, LaMer LLC >27109 Palmetto Drive >Orange Beach, AL >36561 USA This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
3-Phase Power Question
Here's a question for the power engineers in the group. I measured the following phase voltages for the 3-phase power lines feeding a breaker box: phase to phase (all three phases) = 240V phase to neutral (2 of 3 phases) = 120V phase to neutral (1 of 3 phases) = 208V Normally you would expect the phase to phase voltages to measure 208V and the phase to neutral voltages to measure 120V for a Y-connected transformer. What kind of power transformer configuration would provide these phase voltages? Thanks in advance to anyone who can shed some light on this, Richard Meyette meye...@pacbell.net This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Country Deviations to IEC 60950
Group, I have a question regarding the country deviations to IEC 60950, 3rd Edition. Some of the country specific differences are referenced in the IEC standard as notes to the Subclause. For example, 4.3.6 has notes regarding the testing of direct plug-in equipment in Australia and the United Kingdom. Some of the country differences are not referenced directly in the standard. For example Singapore requires a more stringent humidity conditioning test than the test specified in Subclause 2.9.2., however there is no note that references this deviation. Subclause 1.1.2 (Additional Requirements) only has a note stating that the authorities of some countries impose additional requirements. The country specific deviations for the European Union are documented in EN 60950 (Annex ZB, Special National Conditions), and the US and Canadian deviations are contained in UL60950/CSA C22.2, No. 60950. Some of the IEC standards have a list of the specific country differences in the Forward section of the standard, however IEC 60950 does not. So my question is this. Is there a reference source that contains a list of the country deviations for the rest of the world to IEC 60950? Regards, Richard Meyette This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: 60950-1 DoP
Brian, There is a CB scheme Test Report Form for EN 60950-1 and IEC 60950-1 (Form No. IECEN60950_1A) created by SGS Fimko Ltd that is available from the IEC Web Store. http://webstore.iec.ch/ However, I don't know if IEC 60950-1:2001 has been adopted by all of the member countries of the CB scheme to date. Regards, Richard Meyette At 04:47 PM 1/8/03 -0800, you wrote: >Brian - > >EN60950-1 has been published in the ECOJ for the RTTE >Directive, so yes, it can be used for agency certifications >in the EEA. > >Whether or not IEC60950-1 may be used depends on whether or >not the lead agency creating the CB Scheme Test Report form >has completed that task. It used to be FIMKO was the lead >agency, but that may have changed. > > >Regards, > >Peter L. Tarver, PE >Product Safety Manager >Sanmina-SCI Homologation Services >San Jose, CA >peter.tar...@sanmina-sci.com > > >-Original Message- >From: boconn...@t-yuden.com >Sent: Wednesday, January 08, 2003 2:01 PM > >Good People of PSTC >Can EN60950-1:2001 be used agency reports and certificates? >Can IEC60950-1, 1st ed be used for CB reports? >R/S, >Brian O'Connell >Taiyo Yuden (USA), Inc. This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: electric strength test
Group, In Annex ZB to EN 60950:2000, under Clause 1.7.2, Norway has a marking requirement for Class I, Type A pluggable equipment (intended for connection of other equipment) where the safety relies on the connection to protective earth. The marking must state that the equipment is required to be connected to an earthed mains socket-outlet. Sweden has a similar marking requirement under the same clause. If my interpretation is correct, a manufacturer can ship Class 1 ITE products into Norway with only basic insulation from primary to earth ground with this marking, and that they would need to rely on the customer to properly ground the outlets at the installation site. Is this a valid assumption for equipment intended to be installed in telecom locations? What is not clear to me also , is whether these markings can be provided in the installation manual or if it is required to be marked on the equipment. Regards, Richard A Meyette, PE meye...@pacbell.net At 09:37 PM 8/22/02 +0100, you wrote: I read in !emc-pstc that Tyra, John wrote (in <418fbd441c22d5118d860003470d43160543e...@cupid.bose.com>) about 'electric strength test' on Thu, 22 Aug 2002: >If you plan on selling in >this region you should check all of the National deviations and maybe >contact DEMKO (part of UL now) to see if this is still required for the >Nordic countries It applies only to Norway. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: IEC 60825-1, Amendment 2
Tom, Thanks for the reply. After doing some searching on the CENELEC website I was able to confirm that Amendment 2 to EN 60825-1 is harmonized under both the LVD and RTTED with a DOW of 1/1/2004. The CENELEC information also indicates that there are no A-Deviations or Special National Conditions specified for this document, so it should be the same as IEC 60825-1:1993/A2:2001. Regards, R. Meyette At 10:03 AM 8/9/02 +0900, you wrote: On Wed, 07 Aug 2002 17:23:42 -0700, Richard Meyette wrote: > Was Amendment 2 to EN 60825-1 adopted from IEC 60825-1 with no deviations, > or do I need to also purchase a copy of this amendment for CE > certification? What is the DOW for this amendment? I don't know if EN 60825-1:1994/A2:2001 and IEC 60825-1:1993/A2:2001 are exactly identical or not, although I guess (hopefully) they are. For CE marking, EN 60825-1:1994/A11:1996 and EN 60825-1:1994/A2:2001 are listed as the harmonised standards under the LVD (2002/C 57/01), and "date of cessation of presumption of conformity of the superseded standard" of the latter is 1.1.2004. Regards, Tom -- Tomonori Sato URL: http://member.nifty.ne.jp/tsato/ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
IEC 60825-1, Amendment 2
Group, I have a few questions regarding Amendment 2 to IEC 60825-1. I have a copy of IEC 60825-1 Amendment 2 dated 2001-01, that states on page 2 : "The committee has decided that the contents of the base publication and its amendments will remain unchanged until 2003." Does this mean that Edition 1.1 of IEC 60825-1 can be used to certify laser devices until 2003, or is compliance with the revised test procedures in amendment 2 required as of the date of publication? Was Amendment 2 to EN 60825-1 adopted from IEC 60825-1 with no deviations, or do I need to also purchase a copy of this amendment for CE certification? What is the DOW for this amendment? Thanks in advance, Richard A Meyette, PE meye...@pacbell.net --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
NEC Questions
I have a couple of questions regrading the National Electrical Code: 1) Consider a power measuring device that is intended to be installed into a residential 120V branch circuit, protected by a single 15 A or 20 A circuit breaker. The device would be installed into a conduit outlet box on the load side of the breaker to measure the power loads on the outlet receptacles or lights connected to the branch circuit. The device has two neutral terminals with a 12 AWG copper wire connected between them to sense the load currents. This device would be wired in series with the neutral (grounded) conductor for the branch circuit. The live (ungrounded) conductor of the branch circuit would have a common connection on this device. Based on Section 300-13(b) of the NEC (NFPA 70), this device could not be used in a multi-wire branch circuit, since the removal of the device would interrupt the continuity of the grounded conductor. However, I cannot find any requirements that would prohibit the use of this device in a single phase branch circuit, protected by one circuit breaker. Since the resistive loss in the neutral circuit through this device would be negligible, would this device comply with the NEC? My guess is yes, that it meets the NEC code requirements for this branch circuit. Any comments? 2) Consider the same power measuring circuit installed into a direct plug-in (NEMA 5-15P) with a single outlet receptacle (NEMA 5-15R) or into an outlet strip with a 16 AWG power cord with several outlet receptacles. Assuming that the measuring circuit is provided with a suitable fuse for overcurrent protection, are the outlet receptacles required to be protected by a 15 A fuse or circuit breaker in the device or can they rely on the circuit breaker for the branch circuit for overcurrent protection? The UL product standard for this device is UL 3111-1 (Electrical Measuring and Test Equipment), which is harmonized with IEC 61010-1, requires an overcurrent protector to be fitted within the equipment for all devices connected to the mains supply (9.6.2). There are no US deviations in this standard that would allow the circuit breaker to provide this protection, so based on this I would assume that a 15 A circuit breaker of fuse would be required for the NEMA 5-15R receptacles. I would also assume that a 20 A overcurrent protector would be required for a NEMA 5-20R outlet receptacle. However, the UL product standard for household appliances (UL 60335-1) does have a US deviation to a similar requirement for overcurrent devices (19.1, Note 2) that states the "The PROTECTIVE DEVICE in the fixed wiring does not provide the necessary protection." However, the US deviation states "The circuit protection device is permitted to provide necessary protection". If I am interpreting this correctly, a household appliance in the USA could rely on the panel breaker for overcurrent protection. Any comments? Thanks in advance for anyone willing to wade through this and send me a response. Richard A. Meyette. PE meye...@pacbell.net --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: Secondary Grounding
A solution for rack mounted ITE equipment is to have an earth ground terminal on the AC inlet or DC power terminal block that is connected to the chassis. As a second grounding means, the chassis can be provided with two threaded holes for the connection of a Listed grounding lug for bonding the equipment to the metal mounting rack of other suitable grounding point. This ensures that the equipment can reliably grounded, even if the grounding conductor from the supply source is unreliable. The Listed grounding lug would need to be supplied with the equipment. Richard Meyette Terawave Communications 30680 Huntwood Avenue Hayward, CA 94544 Phone: 510-401-6622 Fax: 510-401-6628 Email: rmeye...@terawave.com -Original Message- From: Chris Maxwell [mailto:chris.maxw...@nettest.com] Sent: Friday, June 01, 2001 12:12 PM To: emc-p...@majordomo.ieee.org Subject: RE: Secondary Grounding Hmm, This question centers around whether two separate ground cables equals double protection. Safety standards call for single fault testing. For Class I equipment, one of the single fault test conditions is removal of the ground connection. I'm curious how most test labs would reconcile the two statements above. My guess is that they would interpret removal of ground to mean removal of all ground connections. So putting on an extra ground wire wouldn't help. It would just make the safety engineer disconnect another wire to perform the test. Seems to me that there would be no way to talk them in to this one. No matter how many ground wires you put on, or how well you secure them, they could always say, "What if the product is used in a building or environment with an unreliable ground?" or "How can you garantee that the product's ground potential will always be equal to the potential of the floor where the user is standing" I don't have a comeback for that. If anyone does have a comeback; I'd nominate them for the "Safety Compliance Engineer Hall of Fame" ;-) (I'd also want them to be my lawyer.) !PLEASE NOTE THE NEW EMAIL ADDRESS Chris Maxwell Design Engineer NetTest 6 Rhoads Drive, Building 4 Utica,NY 13502 email: chris.maxw...@nettest.com phone: 315-266-5128 fax: 315-797-8024 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
RE: Disconnect Devices for Telecom Equipment
Tania, The -48V centralized DC power systems used in the central offices of telecommunications companies are limited to 60 VDC or less under normal operating conditions, including during charging of the batteries, and are therefore considered to be SELV by definition. See 3.6 of UL 60950. Annex NAB clearly specifies that the connections to the centralized DC power system must meet the requirements for primary circuits as specified in section 3.2, however there are no requirements for disconnect devices or overcurrent protection specified in this annex. This equipment has operator replaceable fuses for over current protection on the power inputs and has numerous overcurrent devices in the PC assemblies. However, it does not have a disconnect device since it is intended for installation into telecom racks with other equipment that is similarly connected. A disconnect device is required for equipment connected to the AC mains, as specified in 2.7 of UL 60950, however there no requirements for disconnect devices for equipment connected to a secondary SELV source. The centralized DC power systems installed in these restricted access locations are provided with disconnect devices for overcurrect and fire protection. I'm not sure how you would specify the short circuit protection requirements for these systems, since they are not branch circuits covered under Article 240 of the National Electrical Code. Rick Meyette -Original Message- From: Tania Grant [mailto:taniagr...@msn.com] Sent: Wednesday, May 16, 2001 7:18 PM To: Richard Meyette; 'emc-p...@majordomo.ieee.org' Subject: Re: Disconnect Devices for Telecom Equipment Rick, A -48 volt source is considered a secondary circuit, but that does not necessarily make it a SELV circuit. I also don't believe that even if your equipment installation should be proven to be powered by a SELV circuit that the disconnect requirements of Section 2.6 do not apply. Here is why. Note that UL 60950 plainly states that connections to - and overcurrent protection for -d.c. powered equipment needs to meet the same sections as for a.c. main powered equipment. It stands to reason, therefore, that disconnection from whatever mains should also meet Section 3.4.3 (UL 60950) or 2.6 (I presume UL1950. 3rd edition). Annex NAB.2 states that "... connections to the centralized d.c. power system are subject to the requirements for PRIMARY CIRCUITS and shall be in accordance with 3.2 (AC MAINS SUPPLIES)".Sections 2.7.1 and 3.2.1 in Annex NAE which address requirements for d.c. powered equipment refer you back to a.c. mains powered equipment. Also, reading the standard as a whole, Permanently connected equipment, whether a.c. or d.c., needs to meet the stated requirements. (All my references are to the UL 60950 edition.) There are many reasons why it can be considered unsafe not to have immediate access to a disconnect device for any equipment;-- a shock hazard being just one of them. Thus, equipment powered from a SELV circuit is still subject to fire and/or an energy hazard. For fixed equipment, the presumption is that the disconnect device is in the building installation accessible to trained service personnel and, therefore, the relaxed requirement to provide this information in the installation manual. However, I have a larger concern. If you don't have a MAIN disconnect device in your d.c. powered equipment, something tells me that you probably don't have a circuit breaker for overcurrent protection. Annex NAE refers you back to Section 2.7.1 which states that "... If...PERMANENTLY CONNECTED EQUIPMENT relies on protective devices in the building installation for protection, the equipment installation instructions shall so state and shall also specify the requirements for short-circuit protection or overcurrent protection, or, where necessary, for both." I strongly recommend a good read of the complete Annex NAE. Note that UL 60950 has renumbered or reassigned the Section references; the content, however, has not changed from UL 1950 that I have noticed. Tania Grant taniagr...@msn.com <mailto:taniagr...@msn.com> - Original Message - From: Richard Meyette Sent: Wednesday, May 16, 2001 4:35 PM To: 'emc-p...@majordomo.ieee.org' Subject: Disconnect Devices for Telecom Equipment Here's a question for you telecom experts: Paragraph 2.6.3 of UL 1950 (Third Edition) requires permanently connected equipment, that is not provided with a disconnect device, to include a statement in the installation instructions that an appropriate disconnect device shall be provided as part of the building installation. Telecom equipment intended for connection to a -48V centralized DC power system located in a central office is considered to be permanently connected equipment. However, the centralized DC power source is considered to be a
Disconnect Devices for Telecom Equipment
Here's a question for you telecom experts: Paragraph 2.6.3 of UL 1950 (Third Edition) requires permanently connected equipment, that is not provided with a disconnect device, to include a statement in the installation instructions that an appropriate disconnect device shall be provided as part of the building installation. Telecom equipment intended for connection to a -48V centralized DC power system located in a central office is considered to be permanently connected equipment. However, the centralized DC power source is considered to be a SELV secondary circuit. I don't think that this requirement would be applicable in this case, since section 2.6 deals with the requirements for primary power isolation. However, I am being told otherwise. It is no big deal to provide the statement. I would just like to get some clarification on how this requirement is applied to telecom equipment. Rick Meyette Terawave Communications
