3.9 inverse time negative sequence overcurrent protectionPower system occur asymmetric short-circuit and three-phase load imbalance may be the negative sequence current flowing in the stator winding of the generator, and produce harmonic current in the rotor, rotor surface overheating caused, generator's inverse time negative sequence over the protection of rotor flow under the situation not long overheated rotor insulation degradation caused damage to the generator, discrimination protection of generator stator negative sequence current size, consists of three parts:
1) under the time limit: when the negative sequence current is greater than the lower bound value but does not meet the start value of the anti time limit, the alarm signal is delayed by the lower limit;
2) inverse time: when the negative sequence current is larger than the inverse time start value, according to the inverse time lag action equation I22-K t is equal to or larger than a action, type: I2-- generator negative sequence current standard? Value, K - generator operation value of negative sequence current in the standard, a generator rotor surface bear negative sequence current capability of constant;
3) the upper bound limit: when the negative sequence current is greater than the upper bound limit, the upper limit is delayed by the time delay.
Two technical parameter
2.1 Rated parameters
2.1.1Rated DC voltage: 220V or 110V (order indicated)
2.1.2 Rated AC data:
a) Phase voltage V
AC measurement
A group of three-phase current, three-phase voltage and zero sequence voltage, power, frequency, power, power factor
Switch input
11 way switch input, can be the whole set of non electric power for "trip" or "alarm", the first 4 non electricity can be arbitrarily set trip exit
Switch output
8 way switch contact output, the 4 switch jump closing control
control loop
Jump control circuit, circuit breaker hand jump, hand closing operation and hop position indication
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