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Three-phase relay protection tester test

time:2020/6/6   source:华天电力  reading:787 time

The three-phase relay protection tester test is the most important test that every digital relay should perform. In the following cases:

The CT/PT ratio is incorrect.

The relay is not connected to its input signal (CT/PT).

The direction of the relay is wrong.

The phase rotation is backward.

The offline relay test cannot determine 100% of any of these problems, and if any of the last three items are incorrect, the relay will be effectively disabled. What will the relay do during its lifetime? No. What if the relay is disabled by one of these problems? No! If you open it, but there is no action, it does not mean that it is working properly.

Protection Relay Test Set.png

Online meter testing is the only way to ensure that the relay is properly connected to the power system. This article will help you perform effective meter testing.

The first problem encountered by many three-phase relay protection testers when performing on-line instrument testing is the inability to control the inherent ambiguity of the input. Offline instrument testing is easy: apply a value and the relay should report the exact amplitude and angle within the error range. During the test of the meter in use, you do not have to apply fixed values, so you must use some electrical common sense.

Keep in mind that when performing online instrument testing, most relays are usually referenced to Phase A voltage. Let us use some basic electrical theory to understand this knowledge to understand how it is applied to the power system.

The following power system can provide us with different solutions. Try to use the following parameters to infer what each relay will measure:

1) This is a three-phase balanced system.

2) Use the lag angle system in the failure mode of all relay test software.

3) Circuit breakers 1, 4, 3 and 6 are closed.

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