Megger MVCT - Insulation Test

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Winding resistance test is used to determine if the dc resistance of the CT secondary winding is
within specification or not. A DC current is applied and voltage is measured to determine the
winding resistance for the selected tap. After measurement winding resistance is displayed in
digital and analog format on the screen.
Note: A CT should be demagnetized after running the winding resistance test. Run a saturation
test to demagnetize the CT at the completion of all winding resistance tests.
6.5 Insulation Test:
Refer to the safety instructions first before use of the equipment.
1. Verify the Power ON/OFF switch is OFF. Power the test set from a suitable source
of power (95-125 or 195-265 V50/60 Hz).
2. Connect the ground wing nut to a suitable ground.
3. On test lead set labeled CT X/S connect the high voltage connector color coded green to the MVCT
high voltage connector that is color coded green and labeled SOURCE Voltage. Use the red
alignment marks on the 2 connectors to properly align them before connecting.
4. On test lead set labeled CT H/P Connect the high voltage connector color coded blue to the MVCT
high voltage connector that is color coded blue and labeled MEASUREMEMT. Use the red alignment
mark on the 2 connectors to properly align them before connecting
5. On test lead set labeled CT X/S connect the test lead binding posts X1 and X5 to secondary of the
current transformer on the desired tap. Observe the polarity marks on the CT (X1 on test set is
polarity terminal).
6. On test lead set labeled CT H/P connect the test lead primary binding posts H1 and H2 to CT primary
bushings H1 and H2.Observe the polarity marks on the CT (H1 on the test set is polarity terminal).
WARNING
There is always the possibility of voltages being induced at the terminals of a test
specimen because of proximity to high voltage energized lines. A residual static voltage
charge may also be present at these terminals. Ground each terminal to be tested with a
safety ground stick, before making connections.
WARNING
The MVCT produces high voltages and currents during the performance of tests. DO NOT
TOUCH connector clips or test leads while the MVCT is performing a test.