Distribution box, also known as distribution cabinet, is the general term of motor control center. The distribution box is to assemble the switchgear, measuring instruments, protective appliances and auxiliary equipment in a closed or semi closed metal cabinet or panel according to the electrical wiring requirements to form a low-voltage distribution device.
The composition of distribution box is mainly divided into two parts
The first is a complete set of components, that is, the shell of the distribution box and its related accessories.
Second, electrical components and related accessories, namely air switches and their required accessories.
The cabinet is composed of the following parts: circuit breaker; Leakage protection switch; Dual power automatic transfer switch; Surge protective device; Watt hour meter; ammeter; voltmeter.
Circuit breaker: it is not only a switch, but also the main component of the distribution cabinet.
Leakage protection switch: it not only has leakage protection function, but also can trip when people touch live to ensure personal safety. It is the main function of leakage protector; If the electrical equipment is poorly insulated and leaks to the shell, the leakage protector will also trip to avoid electric shock caused by human touch. At the same time, it has current on-off function, overload protection and short-circuit protection function.
Dual power automatic transfer switch: dual power automatic transfer switch is an automatic switching system of one out of two power supplies. It is suitable for uninterruptible power conversion of any two power supplies such as ups-ups, UPS generator and UPS mains.
Surge protector: also known as lightning protector, it is an electronic device that provides safety protection for various electronic equipment, instruments and communication lines. When the electrical circuit or communication line suddenly generates peak current or voltage due to external interference, the surge protector can conduct shunt in a very short time, so as to avoid the damage of surge to other equipment in the circuit.
Watt hour meter: it is an electric energy meter commonly used by electricians. It is an instrument used to measure electric energy, commonly known as watt hour meter.
Working principle of watt hour meter: when the watt hour meter is connected to the circuit, the magnetic flux generated by the voltage coil and current coil passes through the disc. These magnetic fluxes are in different phases in time and space, and eddy currents are induced on the disc respectively. Due to the interaction between magnetic flux and eddy current, the rotating torque is generated to make the disc rotate, and the rotating speed of the disc reaches uniform motion due to the braking effect of magnetic steel.
Because the magnetic flux is directly proportional to the voltage and current in the circuit, the disc moves at a speed proportional to the load current under its action. The rotation of the disc is transmitted to the meter through the worm. The indication of the meter is the actual electric energy used in the circuit.
Ammeter: the ammeter is made according to the action of magnetic field force on the energized conductor in the magnetic field. When a current passes through, the current passes through the magnetic field along the spring and rotating shaft, and the current cuts the magnetic induction line. Therefore, under the action of the magnetic field force, the coil deflects and drives the rotating shaft and pointer to deflect.
Since the magnitude of the magnetic field force increases with the increase of the current, the magnitude of the current can be observed through the deflection degree of the pointer.
Voltmeter: voltmeter is an instrument for measuring voltage. The common voltmeter - voltmeter symbol: v. there is a permanent magnet in the sensitive galvanometer. A coil composed of wires is connected in series between the two terminals of the galvanometer. The coil is placed in the magnetic field of the permanent magnet and connected with the pointer of the meter through the transmission device.
However, the components mentioned above are the most basic components in the distribution box. In the actual production process, other components will be added according to the different uses of the distribution box and the use requirements of the distribution box, such as AC contactor, intermediate relay, time relay, button, signal indicator, KNX Intelligent Switch module (with capacitive load) And background monitoring system, intelligent fire evacuation lighting and background monitoring system, electrical fire / leakage monitoring detector and background monitoring system, EPS power battery, etc.