Annex B Safety Knowledge
65
Where:
a) The network is from GB/T12113-2003 Figure 4;
b) Non- inductance resistance accuracy: 0.1%, capacitance accuracy: 1%;
c) Leakage current I = U2/500R, U2 is rms;
d) Frequency response range: DC ~ 10kHz ~ 1MHz.
B.8 PA and ST
B.8.1 PA
1 Purpose
If the DUT has a rated input power, under normal operating temperature, the deviation
of the input power to the rated power should not exceed the error shown in the table below.
Once the deviation of the power exceeds the error, risks exist. For example, for heating
appliances, high power or high temperature may cause a fire, resulting in dangers to lives and
property. The power devices and wires etc inside the instrument are chosen based on the rated
power. If the power is too high, the instrument will be seriously damaged, causing fire danger.
To avoid accidents, and ensure safety of the environment and the instrument, PA is required
to ensure that the input power of the DUT meets the requirements under in the table.
Heating instruments and
combined instruments
5% or 20W (higher one) -10%
2 PA conditions
PA shall be performed under stable input power of DUT. Stable input power means:
- All circuits which can operate simultaneously are in working condition;
- The instrument is under rated voltage supply;
- The instrument is working under normal condition;
If the current changes in the cycle, the current shall be determined based on the average
current during a representative cycle.
B.8.2 ST
1 purpose
The purpose of ST is to measure and record the instantaneous current, voltage and other
parameters of electric instruments or combined instruments during starting, to analyze and
evaluate the start characteristic of instruments; if the instrument cannot start normally, there
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