für ANNA angelegt 2004-06-25 für ANNA aktualisiert 2004-06-26
Description of a measuring method
Risol
Isolation Resistance
The Procedure
Test of isolation distances and components with constant DC voltage.
Test voltage and the leakage current are measured and recorded.
The resistance is calculated as U/J by PC.
Voltage according to layout of the device up to 2kV or 3kV.
Switch between two measuring ranges:
Range NV: 800V resolution 0.2V
Range HV: 2kV/3kV resolution 1V
Strom je nach Ausstattung des Geräts bis 2mA oder 10mA.
Tms: measuring time - duration from start to reading measuring data.
Ums: Test Voltage
Imax: current limitation in case of failure.
With manual operation generally the leakage current is displayed.
At operation with a PC measured test voltage, leakage current
and the resistance computed from it are available and can be
used independently of each other as criteria for the evaluation
with the help of tolerance borders.
Generally the test runs quick (Tms = 0.3. 0.7s).
Gas discharge arresters should show an isolation resistance
greater than 10 Gigaohm.
Varistoren show a leakage current which can strongly depend
on the voltage and the measuring duration.
As long as test voltage is applied, the leakage current drops
considerably. With repetition of the measurement in the identical
polarity the leakage current remains low and drops further
during the measurement, in reverse polarity the measurement starts
again with a high leakage current.
For the test of Varistors, having possibly minimum damages -
e.g., by current pulses - , an isolation test is recommended
with a D.C. test voltage as high as the expected peak voltage in
normal operation - e.g., 350 V of test voltage for 230Vrms of A.C.
Overview about the measuring methods.
End of Doc