Installation, Operations and Maintenance Manual
1VAL064601-MB Rev C
7
3.3 Testing
Prior to each use, the following tests should be completed
to assure the G&T device is in good condition.
3.3.1
AC Withstand Voltage Test
1. Remove all grounding cables
2. For each terminal complete the following test
sequence:
a. Connect the high potential lead to one pole
b. Ground the remaining poles and G&T device
frame
c. Start machine with output potential at 0 (zero)
Vac/Vdc.
d. For a rated voltage of 15 kV, increase the
potential to 27 kVac RMS. If using dc, the test
potential should be 38 kVdc. For a rated
voltage of 27 kV, increase the potential to 45
kVac RMS or 45 kVdc if performing a DC test.
e. Hold for one minute
f.
Decrease potential to 0 (zero) Vac/Vdc and
turn off machine
3. Repeat this testing for the remaining terminals
A successful withstand indicates satisfactory insulation
strength of the primary circuit.
3.3.2
Current Path Resistance
1. Connect the grounding cables for the terminal set to
be used (upper or lower)
2. Connect one lead from the test set to the ground
shoes on the bottom of the G&T device.
3. Connect the other lead from the test set to the
primary contact of the G&T device terminal to be
tested.
4. Measure the end-to-end grounding path resistance
through the primary disconnect, grounding cables
and ground shoes using a digital low resistance
ohmmeter (DLRO).
The measured resistance should not exceed 100 micro-
ohms.