Charging When Doing Dc Withstand/Ir Test - Chroma 19020 Quick Start Manual

Multi-Channel Sync Hipot Tester 19020/19020-4/19021/19022/19022-4
Quick Start Guide
Resistance test; thus it is necessary to follow the description in section
2.1 for execution.

2.1 Charging When Doing DC Withstand/IR Test

■
Charging
When doing insulation resistance test, the UUT, capacitor, test cable, probe
and output terminal, even the Tester itself may full of high voltage. The
charged voltage may need some time to discharge completely after turning
off the power switch. It is necessary to follow the instruction described
above for actions. Do not touch any area that may cause electric shock
especially when the power is just turned off.
■
Ensure the charged voltage is fully discharged
The time required for fully discharging the voltage depends on the test
voltage applied and the features of UUT. Assuming the high voltage added
on the UUT equals the high voltage added to a 0.01uF capacitor and
paralleled to a 100MΩ resistance circuit. When the test voltage is 1000V,
then it requires approximately 3.5 seconds for the voltage that added to test
and on UUT to fall to 30V under after turned off the power. For 500V test
voltage, it requires about 2.8 seconds. Assuming the time constant of a
UUT is already known, the way described above can be used to calculate
the time required for voltage falling to 30V under after powered off by timing
the time constant multiple to the time decreased to 30V under as Figure 2-2
shows.
<Calculation>
Test voltage * e
Ex : 1000V * e
–t/RC
ln = ln 0.03
-t / RC = -3.5
t = 3.5 sec
4
–t/RC
= residual voltage
–t/RC
= 30V
High Voltage
Output Terminal
Hipot Tester
Return Terminal
Figure 2-2