3.4.25 HPDC - DC HI Pot (EHT)
The dc high-pot (or EHT) test is used to check for safety isolation between windings, or between windings and the core or screens.
During the test, a dc voltage is applied across two groups of windings with the windings in each group being shorted together. The voltage and current are monitored throughout the dwell time; if either the test voltage cannot be maintained, or the current is too large, then a failure will be recorded.
On selecting ‘HPDC High-Pot dc’ from the Available Tests window, a dialogue box will be displayed:
To program the test :
- Enter the test voltage, and the ramp-up and dwell times.
- Enter the terminal names for the High and Low Terminals.
Click with the mouse to select a terminal from the Available list; then click the ‘Add >‘ button to transfer it to the Used list.
(To correct a mistake, click with the mouse to select a terminal from the Used list; then click the ‘< Remove’ button to transfer it back to the Available list.)
- Enter the maximum current value in the bottom section.
- Select OK. The test specification will then be displayed in the program window.