How much do you know about the composition of the distribution cabinet?

The power distribution cabinet is an important part of the power system and the final equipment of the power distribution system. It is mainly used in occasions where the load is relatively scattered and the circuit is relatively small.

The components of the power distribution cabinet are composed of switchgear, measuring instruments, protective appliances and auxiliary equipment. The detailed structure is as follows:


Circuit breakers are important components in power distribution cabinets, usually including air switches, leakage switches, and dual power automatic transfer switches.

The air switch is a switching device that connects, breaks and carries the rated operating current and fault currents such as short circuit and overload in the circuit, and protects it in the case of short circuit.

Leakage switch is a switch with leakage protection function, when people touch the charged object, it will automatically adjust to avoid electric shock. The leakage protection switch has both short circuit protection and load protection functions.

The dual-power automatic switch refers to an automatic power switchover system that automatically switches to the second power supply for load when the first power supply fails, and automatically switches to the first power supply for load when the second power supply fails.



Surge protector

The surge protector is a protective device that provides security protection for various electronic equipment, instruments and communication lines. Surge refers to the transient voltage that exceeds the normal operating voltage. The cause of surge may be short circuit, power switch, etc. When the electrical circuit or communication line produces peak current or voltage due to external interference, the surge protector can switch on the shunt in time to avoid surge damage to other equipment in the circuit.


A surge, also called a surge, is a transient overvoltage that exceeds the normal operating voltage. Essentially, a surge is a violent pulse that takes place in just a few millionths of a second. Possible causes of surges include heavy equipment, short circuits, power switches, or large engines.

A surge or transient voltage is a voltage that substantially exceeds its rated level during the flow of electrical energy. If the voltage exceeds its rated level, it can cause problems, and surge protectors help prevent this problem from damaging the computer.


Watt-hour meter

An hour meter is a meter used to measure electrical energy. There are two kinds of meters, mechanical and electronic, which work differently. Mechanical meters use the interaction of magnetic flux and eddy currents generated by voltage coils and current coils to calculate electricity. An electronic meter uses a chip to measure power.


Electronic watt-hour meter is the use of electronic circuit/chip to measure electric energy; Use a voltage divider or voltage transformer to change a voltage signal into a small signal that can be used for electronic measurement. Use the shunt or current transformer to change the current signal into a small signal that can be used for electronic measurement, use the special energy measurement chip will transform the voltage and current signal analog or digital multiplication, and the accumulation of electric energy, and then output the frequency is proportional to the electric energy pulse signal; The pulse signal drives the stepping motor to drive the mechanical meter display, or sends the microcomputer to process the digital display.



The ammeter is made based on the fact that the current-carrying conductor is subjected to the magnetic field force in the magnetic field. Since the magnitude of the magnetic field force increases with the increase of the current, the magnitude of the current can be judged by the deflection degree of the pointer in the observation room. This kind of ammeter is a magnetoelectric ammeter.


Ammeter usage rules:

①The ammeter should be connected in series in the circuit (or short circuit);

②The measured current should not exceed the range of the ammeter (you can use the method of test touch to see if it exceeds the range);

③ It is absolutely not allowed to connect the ammeter to the two poles of the power supply without going through the electrical appliances (the internal resistance of the ammeter is very small, which is equivalent to a wire. If the ammeter is connected to the two poles of the power supply, the pointer will be crooked in light cases, and it will burn out in severe cases. ammeter, power supply, wires).

④. See clearly the stop position of the hands (be sure to observe from the front).



A voltmeter is an instrument used to measure voltage. In the galvanometer there is a permanent magnet and in the galvanometer there is a coil of wire placed in the magnetic field of the permanent magnet and connected to the pointer by means of a turning mechanism. The voltmeter can directly measure the power supply voltage. When using the voltmeter, it should be noted that the voltmeter must be connected in parallel at both ends of the circuit under test, and the electric range should be selected correctly. The measured voltage should not exceed the range of the voltmeter.