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
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
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
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
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
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
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
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
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