Megger DELTA4000, Instruction Manual, Page: 64 / 74

M
AVTMDELTA4000-EN Rev 6 April 2018
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Tests 12, 13 and 14 are C1 measurements for the other high side bushings. Test
14 is used only if the high winding has a neutral bushing with a test tap. Make
sure to move the Red lead connection from bushing to bushing as necessary.
Test mode is UST-R.
Tests 15, 16, 17, and 18 are C1 measurements for the low side (L) bushings.
Test 18 is used only if the high winding has a neutral bushing with a test tap.
Test mode is UST-R.
NOTE: Many condenser bushings will have factory values for C1 stamped on
their nameplates, both for power factor and capacitance. The test results
for C1 on each bushing can be compared directly to its respective
nameplate values.
Bushing C2 Tests
Bushings with test taps may also be tested to obtain a C2 insulation
measurement. The C2 insulation is the insulation between the test tap
connection and the bushing mounting flange. To perform a C2 test, the HV lead
is carefully connected to the bushing test tap and the Red lead is connected to
the bushing center conductor. Care should be taken not to cause physical
damage to the test tap, as the tap connection point may be a small pin or a
flexible spring. If this is the case, use a small insulated jumper wire or a specially
designed test tap adapter to make the HV lead connection.
G
CAUTION
Bushing test taps have very limited insulation and
should generally be energized at reduced voltage
levels. If the bushing manufacturer does not specify
a test voltage level use no more than 500 volts
(0.5kV).
Tests 20 to 27 are measurements of the individual bushings C2 insulation. All
are performed with test mode GSTg-R. All phase and neutral bushings may be
tested providing they have test taps.
NOTE: Similar to the bushing C1 tests, all the C2 measurements may be made
with the bushing shorting leads still in place from the transformer overall
tests.