GuangDong Wagna Power Technology Co.,Ltd

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Generator Maintenance And Maintenance
- May 12, 2017 -

The following protection shall be installed according to the capacity of the generator for the possible faults and abnormal working conditions of the generator.

(1) longitudinal differential protection: for the stator winding and its lead line of interphase short-circuit protection.

(2) transverse differential protection: one phase to turn short circuit protection for stator winding. Only when the stator winding has two or more parallel branches to form the two or three neutral point leads is provided with this kind of protection.

(3) single phase grounding protection: single-phase earthing protection for generator stator winding.

(4) excitation circuit grounding protection: for the excitation circuit of ground fault protection.

(5) loss of excitation protection, to prevent large generator excitation (low excitation current excitation current is lower than the static stability limit of the corresponding excitation (or lose) the excitation current is zero), from the system to absorb a large amount of reactive power and negative impact on the system, 100MW and above capacity generators are installed this protection.

(6) overload protection: the generator acts on the protection of the signal when it exceeds the rated load for a long time. The small and medium sized generator is only equipped with sub overload protection, and large generator shall be installed with overload of stator and overload of excitation winding respectively.

(7) the stator winding current protection: when the longitudinal differential protection of generator outside short circuit, short circuit protection components or circuit breakers refused to move, such as the protection of external short-circuit backup, the backup protection also doubles as a longitudinal differential protection.

(8) the stator windings of overvoltage protection: to prevent sudden rejection to the full load caused by stator winding overvoltage, hydro generator and turbine generator are installed over voltage protection, small and medium sized turbo generator is usually not installed over voltage protection.

(9) the negative sequence current protection: asymmetric short-circuit or three-phase load power system (single-phase load such as arc furnace electric locomotives, the proportion is too large), will make the rotor end ring, inner surface current density of large parts of the local overheating, burn caused by the rotor, it should be installed in the negative sequence current protection.

(10) out of step protection: step failure protection for large generator and system oscillation process.

(11) reverse power protection: when the steam turbine mistakenly closed, or furnace protection action of the main valve closing and the generator circuit breaker fails to trip, absorb active power from the power system caused by turbine accident, so large units should be equipped with the inverse power relay reverse power protection, for the protection of steam turbine.


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