improve the power system static stability measures?
A: To improve the power system static and stable measures are:
(1) to reduce the system components of the inductive reactance.
(2) the use of automatic adjustment excitation device.
(3) by reducing the load by frequency device.
(4) increase the power system of active and reactive power reserve capacity.
substation of the various energy meters should be equipped with what grade current transformer?
A: The active energy meter, should be equipped with an accurate rating of 1.0 or 2.0 of the current transformer; reactive energy meter should be equipped with 2.0 or 3.0 of the current transformer; transformers, transformers and stations with the station and the power meter used Other electric energy meters for the calculation of electricity shall be provided with current transformers of accuracy class 0.5 or 1.0.
What is compound rectifier? Commonly used multiple rectifier there are several?
A: Double-rectifier is connected to the voltage system by the power supply (voltage source) and the current system connected to the rectifier power supply (current source) with a series and parallel method of reasonable composition, in a system of various operating modes and Fault to ensure reliable, reasonable control of power supply. Commonly used compound rectifier has two kinds of single-phase and three-phase. Single-phase double-rectifier is divided into two parallel and serial wiring.
occurrence of sub-harmonic resonance over-voltage What are the risks?
A: The sub-resonant frequency of the system is quite harmful, in the sub-frequency resonance frequency and power-frequency voltage under the action of PT magnetic flux density quickly saturated, rapidly increasing excitation current, will PT overheating serious damage to the winding ( The same system all PT are threatened), or even cause a bus failure caused a large area blackout.
transformer oil level changes with what factors?
A: Transformer oil level under normal circumstances with the oil temperature changes, because the oil temperature changes directly affect the volume of transformer oil, so that oil within the standard oil level rise or fall. Factors affecting oil temperature changes are load changes, changes in ambient temperature, internal failure and cooling device operating conditions.
on-load tap-changer tap-changer failure is caused by what?
A: It is caused by the following reasons: (1) auxiliary contact in the transition resistance in the process of switching breakdown blown. (2) tap switch is not strict, the water caused by phase short circuit.
(3) As the contact roller stuck, so that the tap switch in the transitional position, resulting in interturn short circuit and burned. (4) tap the tank is short of oil. (5) voltage across the fault current encountered during the process.
transformer on-load tap-changer action failure is what causes?
A: The main reason for the failure of the on-load regulator is:
(1) The operation power supply voltage disappears or is too low.
(2) the motor winding burnout, starter motor pressure loss.
(3) interlock contact poor contact.
(4) Rotating mechanism trip and pin off.
Transformer respirator inside the moisture absorber should pay attention to what?
A: The replacement of breathing apparatus inside the moisture absorption agent should be noted:
(1) should be heavy gas protection to change the signal.
(2) Remove the ventilator should be blocked with the tube to prevent the suction air.
(3) put on a dry moisture absorption agent, the oil should be so that the oil did not breathe out the mouth to seal the respirator.
running in the transformer, according to the sound of its occurrence to determine the operation?
A: The transformer can run according to the sound to determine the operation. With one end of the stick on the transformer tank, the other end on the ear carefully listen to the sound, if it is continuous hum heavier than usual, it is necessary to check the voltage and oil temperature, if no abnormal, Loose core. When you hear a squeak, check the sleeve surface for flashover. When you hear crackling sound, it is the phenomenon of internal insulation breakdown.
What are the basic requirements for relay protection?
Answer: According to relay protection device in the power system in the task, relay protection device must meet the following four basic requirements: selectivity, rapidity, sensitivity and reliability.
Why does relay protection require device fast action?
A: Because the rapid action of the protection device can quickly remove the fault, to prevent the expansion of the accident, to prevent equipment from more serious Damage, but also can reduce the trouble-free low-voltage users in the work of the time and power outages, accelerate the resumption of normal operation process.
