Overview of the application of the hottest lightin

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Overview of the application of lighting distribution boxes and miniature circuit breakers

1 should be tested by pressing the 'run' key instead of pressing the 'rise' or 'fall' key. Lighting distribution boxes are widely used in various buildings, squares, stations, industrial and mining enterprises and other places, as the terminal electrical equipment of power distribution system

2 box structure

the structure of lighting distribution box is divided into closed suspension (open installation) and embedded (concealed installation) according to the installation mode. The main structure is divided into box shell, panel, mounting bracket, neutral bus bar, grounding bus bar and other components. There are opening holes for operating the main switch and shunt switch on the panel. If it is not necessary to install all shunt switches, the opening holes can be partially closed with sealing plates. The tapping holes of incoming and outgoing lines are placed on the upper and lower sides of the box shell. There are also long circular knockout holes on the back, which can be used after tapping according to the needs of users

the lighting distribution box can be divided into steel box, stainless steel box, iron box and plastic box according to the material of the box

3 main electrical components in the box and their protection functions

3.1 miniature circuit breaker (MCB)

is used as the incoming main switch or outgoing sub switch to provide overload and short-circuit protection for distribution lines

3.2 disconnectors

are usually used as incoming switches for power on/off isolation

3.3 leakage protector

generally, the leakage action current of 30mA is selected as the safety protection against personal electric shock

3.4 surge protective device (SPD)

is used to limit the lightning overvoltage conducted from the power line

4 application and safety and reliability of lighting distribution box

as a terminal power distribution equipment, the lighting distribution box is used in a large amount, and its safety and reliability concerns thousands of households, so it should be selected with great caution

4.1 select qualified authentic products

nowadays, there are many fake and inferior products of miscellaneous brands in the lighting distribution box market. Short circuit explosion of box circuit or other electrical faults that directly affect life and work often occur

therefore, qualified and authentic products conforming to the national standard 20 ~ 88hra should be selected. The electrical components in the box should be compatible with the controlled electrical equipment and have perfect protection functions, which is an important link

4.2 correctly design the electrical system of the distribution box according to the national specifications

for example, the national standard code for design of residential buildings (gb50096 should not rise too fast-1999) clearly stipulates: "each residential building should be equipped with a main power circuit breaker, and should use a switch that disconnects the phase line and neutral line when available." It also stipulates that "except for air conditioning power sockets, other power socket circuits should be equipped with leakage protection devices" and "the main power incoming circuit breaker of each residence should have leakage protection function"... The national standard code for design of lightning protection of buildings (GB) also has specific provisions requiring the installation of surge protectors, which must be implemented, because it is related to personal and equipment safety, It is an important means to prevent and reduce the harm of electrical accidents

4.3 consideration of heating, temperature rise and capacity reduction of electrical components

4.3.1 heating and temperature rise

the heat source generated by electrical switches (including miniature circuit breakers) mainly comes from three aspects: current carrying parts, electromagnetic system and dielectric loss. In addition, the arc generated when the switch load is opened and closed can also generate a lot of heat energy in a very short time. However, since the opening and closing of the switch are generally not very frequent, the impact is negligible

therefore, it can be seen that the normal working electrical switch is heated, and the temperature rise is an objective fact

4.3.2 consideration of capacity reduction

generally, the miniature circuit breakers and leakage switches installed in the lighting distribution box are installed closely side by side. Due to the sealing of the box and the mutual influence of the heating temperature between the switches, it is necessary to reduce the rated current of the switch, otherwise the switch will be overloaded and heated, and the temperature rise will be too high to trip. Serious tensile strength testing machines, even with fracture elongation and tensile energy absorption, cause conductor insulation damage, resulting in short-circuit faults and fire accidents

description of accessories

1. types of accessories, complete functions, and different voltage levels for AC and DC systems

2. types of accessories: auxiliary contact, signal contact, shunt tripping, undervoltage tripping, etc

3. function: auxiliary contact --- connected with the switch mechanism to correctly reflect the breaking state of the circuit breaker

signal contact --- displays and transmits information due to overload or short-circuit fault (but it will not work when the switch is manually operated)

shunt tripping - remotely controls the disconnection of the circuit breaker through applied voltage

undervoltage tripping --- when the line voltage drops to 30~70% of the rated value, the circuit will be disconnected, But when the electric pressure of the line fluctuates for a short time (for example, it will not act for 100ms, thus ensuring the continuity of line power supply.

5.2 selective cooperation

in the design and application of miniature circuit breakers, the selective cooperation between the upper and lower levels can generally choose the level difference between the rated current of the overcurrent release of the lower level circuit breaker and the rated current of the overcurrent release of the upper level circuit breaker ≤ 2 to meet the requirements.

6 conclusion

in the fierce market competition, the lighting distribution box with excellent quality is constantly The appearance of. For example, ABB's new ACM series distribution box with a current of 100A is one of them. Its box is made of 1.2mm thick high-quality electrolytic steel plate, and the surface is treated with epoxy resin electrostatic spraying, which can effectively prevent the box from rusting. The electrical components in the box adopt the design of standard guide rail installation and lifting adjustment guide rail support. The problem of assembling components after the box enters the wall is solved. The flat cover design and concealed door cover screws are elegant and beautiful

acm box is equipped with miniature circuit breaker, leakage circuit breaker, surge protector and other electrical components that meet national and international standards and national specifications. Effectively prevent fire accidents and electric shock accidents caused by overload and short circuit. Prevent and reduce the damage of equipment caused by lightning overvoltage, so as to greatly improve the safety and reliability of electricity

s251sna - miniature circuit breaker that simultaneously disconnects phase line and neutral line; S251s - single pole miniature circuit breaker; Gs251 - electronic single-phase leakage circuit breaker; Ovr15 surge protector

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