Hi John:
Also consider that the rectifier will very probably fail due to
excessive reverse voltage under the fault condition, thus allowing fault
current to flow through the transformer winding.
Will the rectifier fail open or short?
This SELV grounding scheme certainly doesn't
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in
20042313.paa09...@epgc196.sdd.hp.com) about 'AW: Define Continuous
DC Voltage', on Wed, 14 Nov 2001:
When the fault occurs between the mains and the ungrounded
SELV pole, 240 volts will appear across the aggregate
1.25-ohm
Hi John:
I presume that the fault current path for the ungrounded
SELV pole must be routed through the SELV source to ground
as that path is the lowest impedance path to ground. It
seems to me that the fault current would have to pass
through the transformer winding. In
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in
20041710.jaa08...@epgc196.sdd.hp.com) about 'AW: Define Continuous
DC Voltage', on Wed, 14 Nov 2001:
A SELV circuit can be grounded. As a result of
connecting the SELV to ground, the name of the circuit
may change to PELV or FELV
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in
20041912.laa08...@epgc196.sdd.hp.com) about 'AW: Define Continuous
DC Voltage', on Wed, 14 Nov 2001:
I presume that the fault current path for the ungrounded
SELV pole must be routed through the SELV source to ground
as that path
Subject: Re: AW: Define Continuous DC Voltage
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in
20040041.qaa06...@epgc196.sdd.hp.com) about 'AW: Define Continuous
DC Voltage', on Tue, 13 Nov 2001:
Hi John:
SELV can protect under single fault conditions. BUT, as I tried
Hi John:
SELV can protect under single fault conditions. BUT, as I tried to
explain, under some conditions, it can allow a single fault *to persist
undetected*, until eventually a second, unrelated fault occurs which
then results in a serious hazard.
This is a
I read in !emc-pstc that John Woodgate j...@jmwa.demon.co.uk wrote (in
bhmfeca9hj87e...@jmwa.demon.co.uk) about 'AW: Define Continuous DC
Voltage', on Wed, 14 Nov 2001:
I said quite clearly that failure of double or reinforced insulation is
acceptable because failure of it has an acceptably low
Hi Vito:
Could either of you clarify why a double insulated SELV circuit can not be
grounded? Is it a 60950 based or based on some other performance(?) based
requirements?
This requires a bit of history. I don't have all of
the history, but I can fill in some of the blanks.
IEC
I read in !emc-pstc that vit...@aol.com wrote (in 117.79cc5a2.29233849@
aol.com) about 'AW: Define Continuous DC Voltage', on Tue, 13 Nov 2001:
Could either of you clarify why a double insulated SELV circuit can not be
grounded? Is it a 60950 based or based on some other performance(?) based
John, Rich;
Could either of you clarify why a double insulated SELV circuit can not be
grounded? Is it a 60950 based or based on some other performance(?) based
requirements?
thx,
vgl
In a message dated Tue, 13 Nov 2001 7:51:18 PM Eastern Standard Time, Rich
Nute ri...@sdd.hp.com writes:
Hi John:
SELV can protect under single fault conditions. BUT, as I tried to
explain, under some conditions, it can allow a single fault *to persist
undetected*, until eventually a second, unrelated fault occurs which
then results in a serious hazard.
This is a problem of the
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in
20031830.kaa06...@epgc196.sdd.hp.com) about 'AW: Define Continuous
DC Voltage', on Tue, 13 Nov 2001:
Hi John:
I have never been very keen on the concept of SELV, and I am glad to see
that others are now recognizing
I read in !emc-pstc that Horst Haug innova...@t-online.de wrote (in
nebbjgdeklhmddlcffinceancoaa.innova...@t-online.de) about 'AW: Define
Continuous DC Voltage', on Sun, 11 Nov 2001:
Enclosed are results of a SELV reliability test. The output inductance was
shorted with no load
Enclosed are results of a SELV reliability test. The output inductance was
shorted with no load and the ripple increased. In 1.2.13.4 (IEC60950) DC
voltage is defined as a voltage with a peak to peak value less 10 % of the
DC voltage.
In the enclosed file you see the ripple with Peak 49,6 Vpmax
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