Hi Xing Weibing:
Here is my answer to the question.
> Hi group I have a question regarding clearance and working voltage of
> IEC60950. If I HAVE A AC ADAPTER(AC 100-240V 50/60Hz) ,THE WORKING
> VOLTAGE MEASURED ARE AS FOLLOWS: Nominal supply voltage: AC240V PRIMARY
> AND SECONDARY : 364V(RMS), 540V(PEAK) MEASURED clearance: 5.3mm I HAVE
> READ SOME CB TEST REPORT FOR THIS THIS SITUATION: SOME REQUIRE: MINIMUM
> CLEARANCE 4.0+0.4mmother require: minimium clearance 6.4mm which is
> correct for this situation? regards Xingwbbtiep2001-11-28
Since the product is an adapter, I will assume that
the question addresses clearance between the mains
circuit and a SELV secondary circuit.
I will also assume that the applicable standard is
IEC 60950, either
2nd Ed (Tables 3 and 4) or
3rd Ed (Tables 2H and 2J).
The parameters are:
nominal mains voltage: 240 V rms
340 V peak
working voltage: 364 V rms
540 V peak
The problem is confused because there is
a set of requirements for working voltage,
in Table 3/H, and
a set of requirements for peak working voltage,
Table 4/2J.
(The 2nd Ed. refers to "repetitive peak voltage;"
the 3rd Ed refers to "peak working voltage.")
According to the standard, if the peak value of the
working voltage exceeds the peak value of the mains
voltage, then the working voltage in Table 3/2H is
taken as the mains voltage. Then, the peak working
voltage (aka repetitive peak voltage) is used in
Table 4/2J.
In the example, the peak value of the working voltage
exceeds the peak value of the mains voltage.
The minimum clearance in Table 3/2H for 240 V mains
and 240 V working is:
4.0 mm reinforced
2.0 mm basic/supplementary
The additional clearance in Table 4/2J for 240 V mains
and 540 V peak is:
0.4 mm reinforced (567 V peak)
0.2 mm basic/supplemenatry (567 V peak)
So, the total clearance is:
4.4 mm reinforced
2.2 mm basic/supplementary.
Arguments? Another view or interpretation?
Best regards,
Rich
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