Brief Introduction of Switchgear

Switchgear is a kind of electrical equipment, the outside of the switchgear first enters the main control switch in the cabinet, and then enters the sub-control switch, and each sub-circuit is set according to its needs.
Such as instrument, automatic control, motor magnetic switch, all kinds of AC contactors, some are also set up high pressure chamber and low pressure chamber switch cabinet, with high pressure bus, such as power plants, some are also set up to protect the main equipment of low week load reduction.
The main function of switch cabinet is to open and close, control and protect electrical equipment in the process of power generation, transmission, distribution and electric energy conversion.
The components in the switch cabinet mainly include circuit breaker, disconnecting switch, load switch, operating mechanism, mutual inductor and various protective devices.
There are many classification methods of switchgear, such as the circuit breaker installation can be divided into moving switchgear and fixed switchgear;
Or according to the different structure of the cabinet, it can be divided into open switch cabinet, metal closed switch cabinet, and metal closed armored switch cabinet;
According to the different voltage levels can be divided into high voltage switchgear, medium voltage switchgear and low voltage switchgear.
Mainly applicable to power plants, substations, petrochemical, metallurgical steel rolling, light industry textile, factories and mining enterprises and residential areas, high-rise buildings and other different occasions.

A.”Five Protection” of High Voltage Switchgear

1. After the vacuum circuit breaker trolley in the high voltage switch cabinet closes at the test position, the trolley circuit breaker cannot enter the working position.(Prevent closing with load)

2. When the grounding knife in the high voltage switch cabinet is in position, the car circuit breaker cannot enter and close.(Prevent the grounding wire from closing)

3. When the vacuum circuit breaker in the high voltage switch cabinet is working on the closing, the rear door of the cabinet is locked with the machine on the grounding knife.(To prevent straying electrical interval).

4. The vacuum circuit breaker in the high voltage switch cabinet closes during operation, and the grounding knife cannot be put in.(Prevent grounding cable from being hung when live)

5. The vacuum circuit breaker in the high voltage switch cabinet cannot exit from the working position of the car circuit breaker when it is in operation.(Prevent pulling brake with load)

B. Classification
Classified by voltage class

According to the classification of voltage level, AC1000V and below are usually called low-voltage switchgear (such as PGL, GGD, GCK, GBD, MNS, etc.), and AC1000V and above are called high-voltage switchgear (such as GG-1A, XGN15, KYN48, etc.).Sometimes the voltage in the high voltage cabinet is AC10kV called medium voltage cabinet (such as XGN15 10kV ring network cabinet).

C. Classified by voltage waveform

Divided into: AC switch cabinet, DC switch cabinet.

D. Classified by internal structure

Pull-out switchgear (such as GCS, GCK, MNS, etc.), fixed switchgear (such as GGD, etc.)

E. By use

Incoming line cabinet, outgoing line cabinet, measurement cabinet, compensation cabinet (capacitor cabinet), corner cabinet, bus cabinet.

Operating procedures
A. Power transmission Procedure

1. Install the back sealing plate first, and then close the front door.
2. Operate ground switch spindle and make it open.
3. Push the hand car (in the open brake state) into the cabinet (test position) with the transfer car (platform car).
4. Insert the secondary plug into the static socket (test position indicator is on), close the front middle door.
5. push the handcart from the test position (open state) to the working position with the handle (working position indicator is on, test position indicator is off).
6. Closing circuit breaker hand car.

B.Power failure (maintenance) Procedure
1 Open the circuit breaker handcar.
Exit the hand car from the working position (open brake state) to the test position with the handle.
3 (the working position indicator is off, the test position indicator is on).
4 Open the front middle door.
5 Pull the secondary plug out of the static socket (test position indicator off).
6. Exit the hand car (in the open state) out of the cabinet with the transfer car.
7. Operate ground switch spindle and make it close.
8. Open back sealing plate and front lower door.

Safety monitoring and protection
Through a series of sensing experiments of various light sources, the characteristics of internal fault arc arc are determined.
On this basis, the optical fiber sensor and an economical and practical distributed multi-point internal fault arc detection and protection device are developed by using arc single criterion rule.
The device has the advantages of simple structure, low cost, fast action time and strong anti-interference ability.
Not only can be used alone, but also can be integrated with a variety of relay protection devices, so that the cost of the switch cabinet is not increased, the technical level and added value are greatly improved.