Hi Ron:
5.4.9.2, IEC 62368-1, is for routine electric
strength testing of solid insulation (there is no
routine electric strength test for clearances or
creepage distances - as if they can be separated).
The routine test voltage is 10% less than the type
test voltage. For 250-volt rated equipment, the
type test voltage is 2500 volts peak, so the
routine test voltage is 2250 volts peak (1591
volts r.m.s.). The test time at 2250 volts peak
is 1-4 seconds.
In the forthcoming IEC 62911, for 250-volt rated
equipment, the electric strength test is 2120
volts peak (1500 volts r.m.s.), minimum. The test
time at 2120 volts peak is 1-4 seconds.
Which standard prevails? Routine testing at the
IEC 62368-1 voltage fulfills both standards,
although IEC 62911 warns that testing at a higher
voltage may deteriorate or partially damage the
insulation. (This statement is bogus; check out
Figure 1, Agilent application note 1074.)
http://web.rfoe.net:8000/ZILIAOXIAZAI/HPB/Contents
/7_Ap_Notes/5965-5977E.pdf
The high-current test will not identify marginal
construction. The test will only identify open
circuits. See PSN Vol. 10, No. 1, January -
March, 1997, and Vol. 10, No. 2 April - July,
1997. A simple low-current continuity test or an
ohmmeter test is sufficient for routine testing of
the protective bonding system. I've made this
comment, formally, to the US TAG, who did not pass
it on to TC108 (I don't know why).
The record-keeping requirement has no expiration
time; this implies records must be kept forever.
Not a problem with today's electronic memory tools
(except the programs for accessing the records may
disappear).
I'm not in favor of IEC 62911 as written. But,
I'm only one voice; majority vote prevails, not
engineering or science.
Best regards,
Rich
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