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Basic knowledge of plant power supply

1. The load center generally has a substation or distribution station, and the increase or decrease of voltage is completed by (transformer).

2, China’s “power frequency” is (50)Hz, frequency deviation plus or minus (0.2)Hz, voltage deviation plus or minus (5%)

3, three-phase AC power system in the operation mode of the power supply of neutral (neutral grounding) system, (neutral grounding through impedance) system, (neutral direct grounding) system.

4, the factory low-voltage power distribution system wiring mode is (radial), (trunk), (mixed), (ring).

5, the dissociation of arc are (thermoelectric emission), (high electric field emission), (collision dissociation), (thermal dissociation).

6. In the primary load, especially important load, in addition to (two) independent power supply, should be added (emergency power supply), and no other load access.

7. The calculated load is the assumed load of the electrical equipment selected according to (heating condition).

8, drop is fuse belongs to (non – limited flow) fuse.

9. Lightning protection device All lightning receivers must be connected with grounding device through (lead off).

10, the basic requirements of relay protection device are (selective), (quick), (reliability), (sensitivity).

11, in the power supply into the line of the special metering cabinet, it is necessary to install the calculation of electricity costs of three-phase (active) and (reactive) watt-hour meter.

12. In factory circuits, the connection between the primary circuit and the secondary circuit is usually made by current transformer and voltage transformer.

13. The most common outdoor distribution network structure of factories and enterprises is (overhead line) and (cable).

14. The functions of the transformer are mainly used for (electric quantity measurement) and (relay protection).

The most common form of failure in power systems is (short circuit).

16. Overcurrent protection device is divided into two kinds (fixed time limit) and (negative time limit).

17. The method to improve the natural power factor is to use measures to reduce the required (reactive power) of electrical equipment to improve its power factor.

18. The power line that delivers the electrical energy from the load center to each customer is called (distribution) line.

19. The low-voltage distribution voltage of the factory is mainly determined by the nature of the plant’s power supply equipment.

20, the main indicators of power supply quality are (voltage), (frequency), (waveform), (power supply continuity).

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Post time: Jul-05-2022