2.10.2.1 General In determining WORKING VOLTAGES, all of the following requirements apply (see also 1.4.8).
a) Unearthed accessible conductive parts shall be assumed to be earthed.
b) If a transformer winding or other part is floating (it is not connected to a circuit that establishes its potential relative to earth), it shall be assumed to be earthed at the point by which the highest WORKING VOLTAGE is obtained.
c) Except as permitted in 2.10.1.5, for insulation between two transformer windings, the highest voltage between any two points in the two windings shall be used, taking into account external voltages to which the windings will be connected.
d) Except as permitted in 2.10.1.5, for insulation between a transformer winding and another part, the highest voltage between any point on the winding and the other part shall be used.
e) Where DOUBLE INSULATION is used, the WORKING VOLTAGE across the BASIC INSULATION shall be determined by imagining a short-circuit across the SUPPLEMENTARY INSULATION, and vice
versa. For DOUBLE INSULATION between transformer windings, the short-circuit shall be assumed to take place at the point by which the highest WORKING VOLTAGE is produced in the other insulation.
f) When the WORKING VOLTAGE is determined by measurement, the input power supplied to
the EUT shall be at the RATED VOLTAGE or the voltage within the RATED VOLTAGE RANGE that
results in the highest measured value.
NOTE Tolerances on the RATED VOLTAGE or RATED VOLTAGE RANGE are not taken into account.
g) The WORKING VOLTAGE between any point in the PRIMARY CIRCUIT and earth, and between
any point in the PRIMARY CIRCUIT and a SECONDARY CIRCUIT, shall be assumed to be the greater of the following:
– the RATED VOLTAGE or the upper voltage of the RATED VOLTAGE RANGE; and
– the measured voltage.
h) When determining the WORKING VOLTAGE for a TNV CIRCUIT connected to a TELECOMMUNICATION NETWORK, the normal operating voltages shall be taken into account.
If these are not known, they shall be assumed to be the following values:
– 60 V d.c. for TNV-1 CIRCUITS;
– 120 V d.c. for TNV-2 CIRCUITS and TNV-3 CIRCUITS.
Telephone ringing signals shall not be taken into account for this purpose.
i) If starting pulses are used to ignite discharge lamps, the PEAK WORKING VOLTAGE is the peak value of the pulses with the lamp connected but before the lamp ignites. The RMS WORKING VOLTAGE to determine minimum CREEPAGE DISTANCES is the voltage measured after the ignition of the lamp. :)学习！ 回去再看
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