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low-voltage electrical components
Sep 21, 2017

First, low-voltage electrical appliances

1, definition

Electrical appliances: components that can switch, control, protect, detect, transform, and adjust the circuit.

High-voltage electrical appliances: refers to the rated voltage of 3000V and above electrical appliances.

Low-voltage electrical appliances: refers to the work in the AC voltage 1200V, DC 1500V and below electrical appliances.

2, classification

Low voltage distribution of electrical appliances: for power supply, such as knife switches, circuit breakers, etc .;

Low voltage control appliances: for control, such as contactors, relays, controllers, etc .;

Low-voltage master electrical appliances: used to send control instructions, such as buttons, the main switch, trip switch and universal switch;

Low voltage protection appliances: for safety protection, such as fuses, thermal relays, voltage relays, current relays and so on.

Low-voltage execution of electrical appliances: for the implementation and transmission of the circuit, such as electromagnets, electromagnetic clutches and so on.

3, the basic structure

1) Electromagnetic mechanism

Composition: attracting coil, iron core and armature composition,

Armature movement mode: direct and type.

Attract the role of the coil: the energy into magnetic energy, the armature in the electromagnetic force under the action of the iron pull.

Voltage coil: parallel in the circuit, the number of turns, fine wire.

Current coil: series in the circuit, the number of turns, wire thick.

AC coil: short and thick, skeleton.

DC coil: thin and long, no skeleton.

In the case of

2) Contact system

The contact is used to turn on and off the controlled circuit.

(1) Contact contact form: point contact, wire contact and face contact.

(2) contact material: silver, embedded silver

(3) arc suppression:

① mechanical arc suppression method: the use of elastic force, quickly elongated arc;

② seam arc method: split arc, and a cooling effect. Such as: vertical seam clay arc cover;

③ gate plate arc method: metal grid split arc;

④ magnetic stripping arc method: the role of electromagnetic force under the rapid elongation of the arc used to extinguish the DC arc