end voltage measurement method.
4. High air humidity
If the air humidity exceeds the standard and results in abnormal increase
(decrease or even negative value) of measurement result and its instability,
add a shell if necessary. However, adding shell by human factor may change
the electric-field distribution of tested article. So this method is debatable and
should be subject to the related regulations.
5. Power supply from generator
In case that the input frequency is unstable when generator works, adopt
50Hz mode.
6. Test cable
Since long term use may result in hidden disconnection of test cable, short
circuit of core and shield or poor contact of plug, user should maintain the test
cable periodically.
When testing the tested article with reference capacitance, the fully
shielded plug should be used to eliminate the impact of additional stray
capacitance. If not, the instrument accuracy cannot be realized.
When measuring CVT with self-exciting method, suspend the
non-dedicated HV cable, otherwise the additional stray capacitance and
dielectric loss to the ground may cause errors.
7. Operating mode selection
Select a correct operating mode for measurement after wiring (UST, GST
and CVT), any mistake is not allowed. Particularly select variable frequency
anti-interference mode under interference environment.
8. Impact of testing method
For the reason that dielectric loss measurement may vary from different
methods, it is important to distinguish test method error from instrument errors.
When faults appear, firstly check wiring and then determine whether the
instrument goes wrong.
9. Instrument fault
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