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Action frequency of relay protection tester

time:2021/9/19   source:华天电力  reading:240 time

Action frequency test range

The start value and end value of the test range of the action frequency should be set near the action frequency. The initial value of the test should be greater than the setting action value of the protection, and the final value of the pilot holding test is smaller than the setting action value.

Protection Relay Test Set.png

The test method of the action frequency: the frequency changes in two stages during the test: the output starts at 50Hz, and after the delay before the change, first press the set df/dt to evenly slide (or slide up) to the test starting frequency, and then press The set step length decreases (or increases) the frequency step by step at a certain time interval. If the protection is activated during the process, the action value will be measured. If there is no action, when it changes to the final value of the test, it is considered that the protection will not be activated and the test of the item is ended.

The time interval of the step-by-step frequency conversion of the microcomputer relay protection tester is automatically determined according to the set action time, which is 0.2S longer than the set action time. Therefore, the setting action time should be set correctly to ensure that the protection has enough time to operate within the changing time interval.

The general test range of low-cycle load shedding test is less than 50Hz, and the test range of high-cycle cutting machine test is generally greater than 50Hz.

For example: the known low-cycle action value is 48.5Hz, the test range can be set to 48.7-48Hz, and the step size is 0.05Hz. The start value and end value of the test cannot be set too small (generally it should not be lower than 45Hz), otherwise the protection will be blocked.

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