Hi Group
I have a question regarding working voltage measurement of IEC 60950
we have a E.U.T.(switching power supply)
I want to clarify the measurement of working voltage
1. Using an oscilloscope having an adequate bandwith and using a high
impedance probe (100Mohm), and adequate integration time to measure working
voltage.
The load on the secondary circuits is to be varied in order to find highest
voltage across the insulation. Floating secondary outputs (capacitively
connected to earth)
are earthed.
2. don't make connection between primary winding and secondary winding.
3. we will get a stable waveform on the oscilloscope.
working voltage we measure are as follows:
The waveform we get by the above method is a kind of waveform modulated by
high-frequency
switching waveform.
MEASURED voltage: 246V(rms),576V(peak)
When we change trigger level and time base to obtain stable switching waveform,
we get different rms voltage
with different trigger level. the highest rms voltage we get is 380V.
My question
1. the above steps are correct or not?
2. For switching power supply, what waveform of working voltage is correct for
primary and secondary
How to obtain?
3. Which one(246V, 380V) is correct for working voltage measurement? or other
methods?
Thank you for any comments in advance
Best Regards
Xing weibing
2001-12-17
