What Is The Internal Structure Of The Distribution Box And Distribution Cabinet?

"Distribution box", also called power distribution cabinet, is a general term for motor control center. The distribution box is a low-voltage power distribution device that assembles switchgear, measuring instruments, protective appliances and auxiliary equipment in a closed or semi-closed metal cabinet or on the screen according to the electrical wiring requirements.

The distribution box is a mass of parameters on the data. Generally, it constitutes a low-voltage forest. According to the electrical wiring, switchgear, measuring instruments, protective appliances and auxiliary equipment are required to be assembled in a closed or semi-enclosed metal cabinet or on the screen to form a low-voltage power distribution. box. During normal operation, the circuit can be switched on or off by means of manual or automatic switches.

The purpose of distribution box:

Reasonable distribution of electric energy to facilitate the opening and closing operations of the circuit. It has a high safety protection level and can visually display the conduction state of the circuit.

The principle of distribution box: The distribution box is a low-voltage distribution box that assembles switchgear, measuring instruments, protective appliances and auxiliary equipment in a closed or semi-closed metal cabinet or on the screen according to the electrical wiring requirements. During normal operation, the circuit can be switched on or off by means of manual or automatic switches. In the event of failure or abnormal operation, the circuit can be cut off or alarmed by means of protective appliances. Various parameters in operation can be displayed by measuring instruments, and some electrical parameters can be adjusted to prompt or send signals for deviations from the normal working state.

Power distribution cabinets (boxes) are divided into power distribution cabinets (boxes), lighting distribution cabinets (boxes), and metering cabinets (boxes), which are the final equipment of the power distribution system. Power distribution cabinet is a general term for motor control center. The power distribution cabinet is used in situations where the load is relatively scattered and there are few circuits; the motor control center is used in the situations where the load is concentrated and there are many circuits. They distribute the electrical energy of a certain circuit of the upper-level power distribution equipment to the nearest load. This class of equipment shall provide protection, monitoring and control of the load.

Power cabinet refers to the combination of electrical control cabinets that provide power for the normal operation of the entire machine, including contactors, frequency converters, high-voltage cabinets, transformers, etc.

Power cabinet function:

1. Supply power to electrical equipment (provide power to the equipment);

2. Start and stop operating electrical equipment (with start and stop buttons);

3. Detect the operation of the equipment (set the signal indicator, have an ammeter and a voltmeter);

4. Protection of electrical equipment (circuit breaker) The power cabinet is a power distribution cabinet, which is a power distribution cabinet that provides power and control for power equipment (generally referred to as motors).

10kv high-voltage cabinets and 400v low-voltage cabinets (regardless of incoming lines, outgoing lines, metering, capacitors, contacts, voltage transformers, etc.) can be called distribution cabinets.

The equipment below the 400v low-voltage cabinet, whose secondary side outlet load is a power facility (such as a fan, motor, water pump, etc.), is called a power cabinet. The load is lamps, switches, sockets and other equipment called distribution boxes.

Distribution box: a small power distribution box, which contains a power switch and a safety device.

Control box: A small control distribution box, which contains a power switch/safety device/relay (or contactor), which can be used for specified equipment control, such as motor control.

Power distribution cabinet: It is actually a large-scale distribution cabinet, which can provide more power or more channels of power output.

Control cabinet: It is actually a large-scale control box, which can provide control output with higher power or more channels, and can also realize more complex control.

Control panel: only the front control cabinet, all internal devices are installed on the panel.

The distribution box is mainly divided into two parts

One is the complete set of components, that is, the shell of the distribution box and its related accessories. The second is electrical components and related accessories, that is, the air switch and the accessories it needs.

There are the following parts in the cabinet. 1. Circuit breaker circuit breaker: not only switch, but also the main component of power distribution cabinet, commonly used are air switch, leakage switch, dual power automatic transfer switch

1. Air switch:

A. The concept of air switch: The air switch is also an air circuit breaker, which is used for making, breaking and carrying rated working current and short-circuit, overload and other fault currents in the circuit, and can cause overload, short-circuit, under-voltage, etc. on the line and load. In such cases, the circuit is quickly disconnected for reliable protection.

There are various designs of dynamic and static contacts and contact rods of circuit breakers, but improving the breaking capacity of circuit breakers is the main purpose. At present, the current limiting principle of limiting the peak value of short-circuit current during breaking by using a certain contact structure has an obvious effect on improving the breaking capacity of the circuit breaker, and is widely used.

B. The working principle of the air switch: The automatic air switch is also called a low-voltage circuit breaker, which can be used to connect and break the load circuit, and can also be used to control the motor that starts infrequently.

Its function is equivalent to the sum of some or all functions of electrical appliances such as knife switch, overcurrent relay, voltage loss relay, thermal relay and leakage protector. It is an important protective electrical appliance in low-voltage distribution network. The automatic air switch has the advantages of various protection functions (overload, short circuit, undervoltage protection, etc.), adjustable action value, high breaking capacity, convenient operation and safety, so it is widely used at present.

2. Leakage protection switch:

A. The concept of leakage protection switch: it has the function of leakage protection, people will trip when they touch the live electricity to ensure personal safety, which is the main function of the leakage protector; if the electrical equipment is poorly insulated and leaks to the shell, the leakage protector will also trip. , to avoid electric shock from human touch. At the same time, it has the function of current on-off, overload protection and short-circuit protection.

B. The working principle of the leakage protection switch:

The working principle of the leakage protector. LH is a zero-sequence current transformer, which consists of an iron core made of permalloy and a secondary coil wound on an annular iron core to form a detection element. The power phase line and neutral line pass through the circular hole to become the primary coil of the zero-sequence transformer. The rear outlet of the transformer is the protection range.

C. The role of leakage protection switch:

1. When leakage or ground fault occurs in electrical equipment or lines, the power supply can be cut off before people touch it.

2. When the human body touches a charged object, the power supply can be cut off within 011s, thereby reducing the damage of the current to the human body.

3. It can prevent fire accidents caused by leakage.

4. Dual power automatic transfer switch:

The concept of dual power automatic transfer switch: the dual power automatic transfer switch is an automatic switching system for two power sources. After the first path fails, the dual power automatic transfer switch automatically switches to the second path to supply power to the load. If the second path fails, the dual power supply The automatic transfer switch automatically switches to the first channel to supply power to the load. Suitable for UPS-UPS, UPS-generator, UPS-mains, mains-mains and other uninterrupted power conversion of any two-way power supply.