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Differential provides a compact testing solution for line, generator, busbar, and transformer differential protection relays. It performs single-phase tests of the operating characteristic (pick up value, slope test) and the inrush blocking function (harmonic restraint test).
Variable tap settings, as for some older electromechanical relays (e.g. GE BDD, or Westinghouse HU) can be addressed.
For the operating characteristic test, test points are defined in the Idiff/Ibias plane either by the mouse or by using the keyboard. A graphic user interface makes the test definition easy.
Differential also tests the harmonic restraint function. For this function, the test points are determined by the differential current and the percentage of the superimposed harmonic.
The test currents belonging to the test points are injected into the relay and the reaction of the relay is assessed.