供电常识（The power supply common sense）.doc

供电常识（The power supply common sense） N: 1. Loss of magnetism: the loss of magnetism refers to the interruption of excitation current caused by certain faults in the excitation circuit during operation of the generator. Zero sequence current: zero sequence current occurs in the system when a single or two grounding short circuit fault occurs in the power system. At this point, at the ground fault point will be a zero sequence voltage, the voltage tends to zero sequence current, under the action of zero sequence current from the point of failure after the earth to the neutral point grounding electric equipment return point of failure for the circuit is a kind of special reflection of ground fault current. High frequency current: the high frequency signal current in the high frequency protection circuit. This current is named after the current frequency current, and the frequency current changes 50 times per minute, while the high-frequency current varies by 35KHZ. The frequency of the current system is generally 35 ~ 500KHZ. 4, breakdown voltage, insulation materials under the effect of voltage, the timeout a certain critical value, medium suddenly lose their insulating ability and phenomenon of electricity discharge is called breakdown occurs, the critical value is called the breakdown voltage. 5. Increasing current: the increase of current is an additional current that affects the right work of distance protection. Because in many cases, the connection between protection installed at the point of failure have other branch current, the power supply will supply additional short circuit current, make through the fault line current is greater than the current flowing into the protective device. This current is called a boost current. 6. Capacitance type voltage transformer: the voltage transformer with voltage transformer is realized by the principle of capacitive pressure voltage transformer. 7. High frequency processing equipment: high frequency resistor, coupling capa