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Installation, Operations and Maintenance Manual
Figure 17: Lower terminal configuration in
disconnected position with ground bus
installed
Figure 18: Upper terminal configuration in
disconnected position with ground bus
installed
12. With the ground bar attached, close and secure
the switchgear breaker compartment door and
rack the device into the "connect" position.
13. With the ground bar installed and the device
racked into the "connect" position, the terminal
set is connected to the switchgear ground bus.
Courtesy of NationalSwitchgear.com
1VAL064601-MB Rev C
4.2 Removing Ground/Withdrawing the Device
1. Rack the device to the disconnected position.
2. Open the switchgear breaker compartment
door, disconnect and remove the ground bar.
4.3 Testing
Prior to each use, the following tests should be completed
to assure the G&T device is in good condition.
4.3.1 AC Withstand Voltage Test
1. 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. Increase the potential to 27 kVac RMS.
If using DC, the test potential should be
38 kVdc.
e. Hold for one minute.
f.
Decrease the potential to 0 (zero)
Vac/Vdc and turn off the maching.
2. Repeat this testing for the remaining terminals.
A successful withstand indicates satisfactory
insulation strength of the primary circuit.
4.3.2 Current Path Resistance
1. Connect the ground bar for the terminal set to
be used (upper or lower).
2. Connect one lead from the test set to the ground
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 set
to be tested.
4. Measure
the
resistance through the primary disconnect,
grounding cable, and ground shoes using a
digital low resistance ohmmeter (DLRO).
The measured resistance should not exceed 100
micro-ohms.
end-to-end
grounding
path
10
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