RE: Crepage/Clearance On Telecom Modem design

1998-10-12 Thread Mel Pedersen
This is my understanding of the situation Barry. If one considers the worst case (DC) voltages that could possibly exist on TNV-3 lines and also SELV circuits, and considers the likelihood that these are at opposite polarity, one would obtain a worst case 180VDC = -120VDC (TNV-3) - 60VDC

Conformity Assessment seminar

1998-10-12 Thread ron_pickard
To all that might be interested, Communication Certification Lab (CCL) is putting on a Conformity Assessment seminar on October 29 30, 1998 in Salt Lake City. I will be attending and have attended this seminar in the past. I've always been able to use the information presented. If

Re: Crepage/Clearance On Telecom Modem design

1998-10-12 Thread JPR3
In a message dated 98-10-12, Mel Pederson writes: If one considers the worst case (DC) voltages that could possibly exist on TNV-3 lines and also SELV circuits, and considers the likelihood that these are at opposite polarity, one would obtain a worst case 180VDC = -120VDC (TNV-3) - 60VDC

Re: Shield Room Grounding

1998-10-12 Thread ed . price
Bob: Barry is trying to say that a dummy power load is only resistive at the power frequency, and may not truly represent the EUT at all of the other frequencies within the test range. He's right. Bob suggests a powerline filter be added to my El Cheapo lightbulb load bank to more closely

RE: Crepage/Clearance On Telecom Modem design

1998-10-12 Thread Mel Pedersen
Also, one other thing to keep in mind is that 150VDC is only the working voltage for determining the creepage distance...to determine the proper clearance and Dielectric withstand test, one must take the peak ringing voltage into consideration. The applicable clearance here, would be 1.4mm

Re: RATED VOLTAGE UL1950

1998-10-12 Thread Robert Johnson
This is being cleared up in the third edition of IEC 60950. It has been undefined in previous versions of the standards. Agencies have each chosen values to use, but you should be able to argue for the following since most countries have already agreed to this proposal in their voting on the

Re: RATED VOLTAGE UL1950

1998-10-12 Thread Kaan_Gregersen
Hello Group, Just to add my two cents... Let us not forget Clause 2.2.7.2 which (as I understand it) indicates that for Clearences for Primary Circuits (Table 3); ELV, SELV, and TNV circuits are considered to have 0 volts. This clause seems to indicate that while determining the working voltage

Re: Conformity Assessment seminar

1998-10-12 Thread Richard Haynes
Ron, Thanks for the note. I also think such information should be shared. Word of mouth or e-mail is sometimes the best way because along with the seminar information comes an evaluation and can save time and money. Thanks again even if the management disagrees. Richard Haynes -Original