source：jinzhong transmission and distribution time：2020-11-24 Number of hits：1171of hits
"Distribution box", also known as distribution cabinet, is a general term for motor control. According to the requirements of electrical wiring, the switchgear, measuring instruments, protective appliances and auxiliary equipment are assembled in a closed or semi enclosed metal cabinet or panel to form a low-voltage distribution device.
Purpose of distribution box
It is convenient for circuit maintenance and management. Distribution box and distribution cabinet, distribution board, etc., is a complete set of equipment for centralized installation of switches, instruments and other equipment.
Guizhou power distribution equipment commonly used distribution box has wood and iron plate two kinds, now where the power consumption is quite large, so iron is more used. The purpose of the distribution box: of course, it is convenient to stop and transmit power. It plays a role in measuring and judging the power stop and transmission.
The cabinet consists of the following parts
Circuit breaker
Circuit breaker: both switch, is the main component of distribution cabinet, commonly used air switch, leakage switch, double power automatic transfer switch
1. Air switch:
A. Concept of air switch:
The air switch is also called air circuit breaker, which can make and break the circuit and carry the rated working current, short circuit, overload and other fault current in the circuit, and can quickly break the circuit in the case of overload, short circuit and under voltage of the line and load, so as to provide reliable protection.
There are various design types of dynamic contact, static contact and contact rod of circuit breaker, but the main purpose is to improve the breaking capacity of circuit breaker. At present, the current limiting principle of limiting the peak value of short-circuit current when breaking with a certain contact structure has obvious effect on improving the breaking capacity of circuit breaker, and is widely used.
B. Working principle of air switch:
Automatic air switch, also known as low voltage circuit breaker, can be used to connect and break the load circuit, and also can be used to control the motor which starts infrequently. Its function is equivalent to the total function of knife switch, over-current relay, loss of voltage relay, thermal relay and leakage protector. It is an important protective device in low-voltage distribution network.
Autmatic air switch has a variety of protection functions (overload, short circuit, under voltage protection, etc.), adjustable action value, high breaking capacity, convenient operation, safety and other advantages, so it is widely used.
Leakage protection switch 2
A. Concept of leakage protection switch:
The main function of the leakage protector is to ensure personal safety by touching the live line. If the insulation of the electrical equipment is not good, the leakage protector will also trip to avoid touching electric shock. At the same time, it has current on-off function, overload protection and short-circuit protection function.
B. Working principle of leakage protection switch:
Working principle diagram of leakage protector. LH is a zero sequence current transformer. It consists of a permalloy core and a secondary coil wound on the annular core. The phase line and neutral line of the power supply pass through the round hole and become the primary coil of the zero sequence transformer. The rear outlet of the transformer is the protection range.
C. Functions of leakage protection switch:
1. When the electric equipment or circuit leakage or grounding fault, can be before the human touch to cut off the power supply.
2. When the human body touches the charged object, it can cut off the power supply within 011s, so as to reduce the damage of electric current to human body.
3. It can prevent fire accidents caused by electric leakage.
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