Eaton EMR-4000 Installation, Operation And Maintenance Manual page 641

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Commissioning: Underfrequency [ANSI 81U]

For all configured underfrequency elements, this test can be carried out similar to the test for overfrequency protection

(by using the related underfrequency values).

Please consider the following deviations:

For testing the threshold values, the frequency has to be decreased until the protection element is activated.

For detection of the fallback ratio, the measuring quantity has to be increased to more than 100.05% of the trip

value (or 0.05% fn). At 100.05% of the trip value the relay is to fall back at the earliest (or 0.05% fn).

Commissioning: 81R Rate of Change (df/dt)

Object to be tested:

All frequency protection stages that are projected as df/dt.

Necessary means:

Three-phase voltage source and

Frequency generator that can generate and measure a linear, defined rate of change of frequency.

Testing the threshold values

Keep on increasing the rate of change of frequency until the respective element is activated and

Note the value.

Testing the trip delay

Set the test voltage to nominal frequency:

Now apply a step change (sudden change) that is 1.5 times the setting value (example: apply 3 Hz per second if

the setting value is 2 Hz per second); and

Measure the tripping time at the relay output. Compare the measured tripping time to the configured tripping

Successful test result:

Permissible deviations/tolerances and dropout ratios can be taken from the Technical Data.

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