These are the
routine, type, and other tests that are necessary to assure that the
design and construction of the transformer are adequate to meet the
specified requirements.
Routine Tests
Each instrument
transformer shall receive the following routine tests at the factory.
These tests shall be made on the instrument transformer after
complete assembly, where feasible.
a) Applied voltage
dielectric tests between windings and between windings and ground
(with the exception there is no primary insulation test for bushing
type, split-core, or any current transformer designed with incomplete
insulation for the primary conductor)
b) Induced voltage
tests
c) Accuracy tests
d) Polarity test
Type Tests (design tests)
Type tests shall
be performed on at least one transformer of each design group that
may have a different characteristic in the specific test.
Transformers subjected to type tests shall withstand the applicable
routine tests before and after the type tests. It is not necessary to
conduct more than one type test on the same unit.
Type tests for
voltage transformers shall include:
a) Impulse (BIL)
test
b) Wet 60 Hz 10 s
withstand test
c) Short-time
mechanical withstand test
d) Temperature
rise test to verify the rating factor
e) Accuracy test
to verify quoted accuracy ratings
Type tests for
current transformers shall include:
a) Impulse (BIL)
test
b) Wet 60 Hz 10 s
withstand test
c) Short-time
mechanical current rating test
d) Temperature
rise test to verify the thermal burden rating
e) Accuracy test
to verify quoted accuracy ratings
f) Switching
impulse test, if applicable
Other Tests
Other tests are
additional tests made for application information, for provision of
specific data requested by users, for verification of type
capability, etc. Examples of other tests are:
a) Special
accuracy tests
b) Open-circuit
secondary voltage magnitude or withstand capability on current
transformers
c) Voltage
transformer capabilities in respect to 125%, 140%, and 173%
overvoltage characteristics required
d) Radio influence
voltage test (RIV)
e) Partial
discharge test
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