Dielectric Discharge (1537/1537-Ii Only) - Fluke 1537-II User Manual

1535/1537/1537-II
Users Manual

Dielectric Discharge (1537/1537-II only)

The dielectric discharge (DD) test, also known as the re-absorption current test, is a
measurement of the current during dielectric discharge of the equipment being tested.
The measurement principle is as follows:
1. Equipment to be tested is first charged for 30 minutes to reach a stable state
(capacitance charging and polarization are completed and the only current
flowing is the leakage current).
2. Equipment is then discharged through a resistor inside the megaohmmeter and
the current that flows is measured. This current is made up of the capacitance
charging current and the re-absorption current that combines to give the total
dielectric discharge current. This current is measured after a standard time of
1 minute. The current depends on the overall capacitance and the final test
voltage. See Figure
The value DD is calculated with this formula:
I
DD =
V × C
I = current after 1-minute discharge
V = voltage before discharge
C = measured object capacitor
1
4x = DD
12
5.
Figure 5. Dielectric Discharge
2
I
DD =
V x C
I
= current after 1-min. discharge
V
= voltage before discharge
C
= measured object capacitor
Discharge
1 min.