In the transformer no-load input power supply or external fault voltage recovery process after resection

Transformer differential protection as main protection for quick removal transformer internal fault plays an important role. Load power on the transformer or the external fault voltage Electric energy meter process, are generated inrush current, especially in the closing voltage of 0 V, the magnetic flux in the transformer core increases rapidly, instantaneously saturate the iron core, there big impact excitation current value (up to 5 to 10 times the rated current), often referred to as  circuit breakers . Inrush current treatment directly affects the choice of means to the differential protection action behavior may lead to differential protection tripping or malfunction. Transfer from the hot spare transformer operation, main transformer, the ratio differential protection tripped the switch on each side of the main transformer; transformer, the percentage  air circuit breaker  again the action, jump on each side of the main transformer switch. Differential protection immediately after the inspection station equipment without exception; relevant checks carried out on the transformer, primary equipment insulation inspection and oil samples for testing are satisfactory; protection device checks the 2nd Main Transformer Protection of second harmonic restraint and related protection logic function tests, the action is correct.