RE: Delta transformer grounding (was: RE: GFCI in IT (three phase) Ne tworks)

:47 AM Peter Tarver wrote: Delta-delta transformers are popular with the utilities for economy's sake (they are less expensive than WYE transformers) For similar reasons, some industrial applications distribute and use power within their plants on delta feeds. In office environments

RE: Re[2]: Coupling Capacitors 950

Ron - Different UL standards have different requirements for these capacitors. It is my understanding that: UL1950 (ITE) does not have an issue specifically with UL1283 capacitors (yet) UL1459 (Telephone Equipment) does have requirements specifically requiring UL1414 capacitors (which if

RE: Sound Pressure Meter

Ned - Since you didn't mention your particular application, a good source for a very broad number of applications is Bruel Kjaer http:\\www.bk.dk Their regional US representatives moved to a central North American location Bruel Kjaer Division of Spectris Technologies

FW: clearance IEC1010

When I sent this out, I selected reply to sender, rather than to all. Here's what Rich got. For your perusal. Peter L. Tarver Nortel ptar...@nt.com -- From: Tarver, Peter (P.T.) Sent: Friday, December 12, 1997 8:30 AM -- From: Rich Nute[SMTP:ri...@sdd.hp.com] Sent:

RE: The FDA and Laser Products

Doug, et al - The FDA is concerned about contacting a responsible company, should any incident(s) occur for any given product. This would be to affect recalls and/or repairs/modifications, etc., to Certified equipment. Also, this is intended to allow a user to contact the responsible company

RE: Hipot testing AND current

Further to Rich's comments... -- From: Rich Nute[SMTP:ri...@sdd.hp.com] Sent: Thursday, December 04, 1997 10:38 AM Hello Vagn: 1. Why do standards specify a minimum output current for hi-pot testers? deletia Another reason for a minimum current requirement is that some of the

RE: PCB Temperatures

Of equal concern for minor excessive temperatures, is that the bond strength of the copper on the PWB will be the first thing affected. The copper may pull away from the laminate due to thermal stresses and eventually result in high impedance connections. Such poor electrical connections could

RE: [Commercial (HazCom Solutions)]

This kind of commercial post is explicitly forbidden by the Charter of the EMC-PSTC listserver. Please don't do it again. Peter L. Tarver Nortel ptar...@nt.com -- From: Adrian Aldape[SMTP:b...@centuryinter.net] Sent: Wednesday, July 09, 1997 1:13 PM To:emc-pstc Subject:

RE: UL 1950, Clause 3.2

Relocatable power taps are considered temporary extensions of the branch circuit. They are not appliances and that is the crux of the issue. Placing any active electronic circuitry inside (I assume this is what you mean by contains other control circuits), other than passive surge and

RE: UL 1950 Clarification Needed

-- From: donne...@agcs.com [SMTP:donne...@agcs.com] Sent: Tuesday, June 24, 1997 12:29 PM I am wrestling with the concept of clearances as they apply to our -50Vdc power circuits in a telecom application. Looking at UL 1950 (3rd edition), Clause 3.4.1 says that the connections to a

RE: Interlock - PCB Spacings -- OPINION PLEASE

Well put, Chris. On this same topic, I've been curious for many years now about the suitability of Hall Effect sensors in interlock circuits. Any comments? Peter L. Tarver Nortel ptar...@nortel.com -- From: Chris Dupres[SMTP:chris_dup...@compuserve.com] Sent: Monday, June 23, 1997

RE: Class I laser . U.S. vs EN 60825

Bob - The limits are similar, but not identical, (yet). As to the failure mode considerations, IEC 825-1 contains requirements for imposing fault conditions on components and the like that might affect the laser class. This is probably the origin of the safety notice. Please note that fault

FW: Fire Enclosures

Richard - It is my understanding that if an enclosure is built in accordance with the construction specifications in the standard, it will already meet the requirement to prevent the spread of flames. No additional text needs to be added to the standard in this area and any attempt to do so will

RE: Spark-Gaps and clearance rules

Below, Bruce Hunter assumes Hans Mellberg is using an air gap comprised of traces on a printed wiring board. When I first read Hans' message, I thought he was discussing discrete components. I have seen both used, but would like to ask you, Hans, to clarify your application, before we get off on

RE: Surge currents when powering up equipment..

The safety agencies will primarily look to see if the inrush will cause nuisance tripping of any overcurrent protection devices, including the branch circuit protection, and sometimes effects on additional earth leakage current. For your application, the North American agencies will assume branch

Re: UL Marks and Repair of

Cortland Richmond wrote: Rich, This the City's own testing laboratory and labelling service. sounds odd. Is the City of Los Angeles running a NRTL? Heck, if I'd known that I would not have bothered sending for UL. Cortland Not an NRTL, Cortland, just their own test lab. Many have been

Re: Laser measuring equipme

Or, try Melles-Griot. Their general catalog also lots of basic optics information you may find useful. They have a sales office in Boulder, CO: 4665 Nautilus Court South Boulder, CO 80301 fax: 303-581-0960 Regards, Peter L. Tarver Nortel peter_tarver-mt...@nt.com

FWDREIEC-950 4th Amendmen

Mail*Link® SMTP FWDREIEC-950 4th Amendment - E X T E R N A L L Y O R I G I N A T E D M E S S A G E - Just received notice that Amendment 4 to IEC Publication 950 was published in August 1996. It was prepared by IEC TC 74 which prepares requirements for the safety and

Re: UL/TUV requirements

Michael - If the filter is UL Recognized, you might wind up asking for trouble. First off, the markings on the outside of the can are what identify the filter as Recognized (mfg's. name and cat. no., and the backwards UR ligature). Removing the can removes traceability of the filter and

Re: Magnet wire

Judd and Art - I know this particular product well. It was one of my projects, while working at UL. I can't give you many details, on ethical grounds, but IMO, it's good stuff, within its Recognized limits. Please note that: the manufacturer in the 1996 UL RCD is Furukawa Electric

Re: Conductive Coating, IEC

One point that must be made clear on the QMRX2 -vs- QMSS2 product categories. As an end-product manufacturer, the purchasing agent should use QMRX2 exclusively, where ever possible. Doing so ties one into the actual company applying the coating to the specific part and, if selected on the

Re: Insulation

Believe it or not, Eric, there are some 30 V rated cables. They're usually better insulated than that, IMHO, but, the surface markings say 30 V. Usually some kind of data cable. Regards, Peter L. Tarver peter_tarver-mt...@nt.com -- rated voltage of 30V.

Re: Insulation

Simply, no. There are special tests performed to determine if a cable is made from low smoke producing, slow burning insulating materials. The UL Standard is UL 910. The type of Listed (not Recognized Component) cables that are appropriate for use in plenums have the cable designation

FWDhelp

Mail*Link¨ SMTP FWDhelp Doe sanyone out there know where Paul is and can check up on him? Peter Tarver Northern Telecom peter_tar...@nt.com -- List-Post: emc-pstc@listserv.ieee.org Date: 6/21/96 6:06 AM From: Paul Reilly - E X T E R N A L L Y O

Industrial Plug and Socket

Tom Bao asks about what configurations make products Pluggable Equipment Type B. Where North America is concerned, this was discussed at UL and it was essentially determined that any attachment plug other than , ANSI/NEMA 1-15P, 5-15P and 5-20P (the 125V, 15A and 20A plugs) makes ITE Pluggable

Re: FW: Infrared Viewers

Reply to: REFW: Infrared Viewers Keith - While I don't have any direct experience with IR imagers and their related analysis software, I would suggest getting your hands on some trade magazines, such as Photonics Spectra, Lasers and Optronics, etc. There are at least a few vendors

Re: Merger of Component Man

Reply to: REMerger of Component Manufactures All - While the emphasis in this discussion has been on ways to bandaid(tm) reports to avoid FUS problems for OEMs, I see this as a problem with the way FUS is coordinated by the safety certifiers. While at UL, mergers of companies proved

FWDRELimited Power Sourc

Reply to: FWDRELimited Power Source Egon H. Varju wrote: On 20/4/1996 Kendal Wilcox wrote: I was discussing UL 1950/CSA950/EN60950 clause 2.11, Limited Power Source with a colleague, and we were looking at the Table 9 limits for maximum output current Isc (1000/Uoc)

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