Circuit breakers, contactors, intermediate relays, thermal relays, buttons, indicator lights, universal transfer switches and travel switches are the eight most common components in electrical control circuits. The editor introduces the principles and applications of common electrical components with pictures and texts. Get a handle on how these components work in normal times by understanding their role in the electrical circuit.
1. Circuit breaker
Low-voltage circuit breakers are also called automatic air switches, which can be switched manually, and can be used to distribute electric energy, start asynchronous motors infrequently, and protect power lines and motors. Automatically cut off the circuit.
◆Outline drawing of commonly used circuit breakers
2. Contactor
The contactor is composed of two parts, the electromagnetic mechanism and the contact system. The common coil voltages of the contactor are AC220V, AC380V and DC220V. The electromagnetic mechanism of the contactor is composed of a coil, a moving iron core (armature) and a static iron core; the contactor contact system is composed of two parts, the main contact and the auxiliary contact, the main contact is used to switch the main circuit, and the auxiliary contact is used to control in the circuit.
◆Outline pictures of commonly used contactors
Button control principle with Gqele
Definition: A switch that uses a button to push the transmission mechanism to make the moving contact and the static contact on or off and realize the circuit switching.
Introduction: The push button switch is a kind of master electrical appliance with simple structure and wide application. In electrical automatic control circuits, it is used to manually send control signals to control contactors, relays, electromagnetic starters, etc. Button switch real type
There are many types of button switch structures, which can be divided into ordinary push button type, mushroom head type, self-locking type, self-resetting type, rotary handle type, indicator light type, light symbol type and key type, etc. There are single button, Double buttons, three buttons and different combination forms generally adopt building block structure, which is composed of button cap, return spring, bridge contact and shell, etc., usually made into a composite type, with a pair of normally closed contacts and normally open contacts , Some products can increase the number of contact pairs by connecting multiple components in series. There is also a self-holding button that automatically holds the closed position after being pressed, and can only be opened when the power is turned off.
Classified according to the purpose and structure of the contact
(1) Normally open button
(2) Normally closed button
(3) Compound button classified according to operation mode and protection mode Buttons can be classified according to operation mode and protection mode, common button categories and characteristics:
(1) Open type: suitable for embedded and fixed on the panel of switch board, control cabinet or console.
(2) Protective type: with a protective shell, which can prevent the internal button parts from being mechanically damaged or people touching the live parts.
(3) Waterproof type: with a sealed shell, which can prevent rainwater from intruding.
(4) Anti-corrosion type: it can prevent the intrusion of chemical corrosive gases.
(5) Explosion-proof type: It can be used in places containing explosive gas and dust without causing explosion transmission, such as coal mines and other places.
(6) Illuminated button: There is a signal light inside the button, which is not only used to issue operation commands, but also serves as a signal indicator, and is mostly used on the panels of control cabinets and consoles.
(7) Key type: Insert and rotate with a key to operate, which can prevent be operated by a special person.
(8) Emergency type: There is a big red mushroom button protruding outside, which is used to cut off the power supply in case of emergency.
(9) Self-holding button: The button is equipped with a self-holding electromagnetic mechanism, which is mainly used in power plants, substations or test equipment. Operators communicate with each other and issue instructions, etc., and are generally panel-operated.
(10) Knob type: The contact is operated by rotating the handle, with two positions of on-off, generally panel-mounted.
(11) Combined type: combination of multiple buttons. (12) Interlocking type: Multiple contacts interlock with each other. Code-named off, on.
The main technical parameters
Switch rating: ac-15 36v/10a 110v/10a 220v/5a 380v/2.7a 660v/1.8a dc-13 24v/4a 48v/4a 110v/2a 220v/1a 440v/0.6a
Conventional thermal current: 1th 10a
Electric shock Resistance: ≤50mΩ
Insulation resistance: ≥10mΩ
Mechanical life: general button n≥100×10 times; knob ≥30×10 times.
Key button n≥5×10 times; emergency stop button ≥5×10 times
A rotor on which a moving contact is attached is received and rotatably held in a body, and a knob is received and held in the body side by side with the rotor and is movable. A plurality of first and second teeth are circumferentially staggered with each other on an outer perimeter surface of the rotor near one end and near the other end, respectively, in the direction of the axis of the rotor to project from the surface. An inclined surface is formed in each of the first and second teeth. A projecting part is formed on the knob to project toward the rotor. In response to a depression of the knob, the projecting part pushes the inclined surface of the second teeth to rotate the rotor and, in response to a return of the knob, pushes the inclined surface of the first teeth to rotate the rotor.
The invention provides a push-button switch including: a star wheel which is rotated by a constant angular step in one direction by a depression of a push button that automatically returns; an indenter which is pressed against the outer periphery of the star wheel by a spring; a contact which is attached so as to corotate with the star wheel, and which serves as a movable contact; and terminals with which the contact is contacted in accordance with a rotation angle, and which serve as stationary contacts. A small projection having a rounded tip end is disposed in each of ridge portions of the star wheel. Even when the slope of each ridge portion does not have a large inclination angle, the star wheel is prevented from being stopped at a position where the ridge portion is opposed to the indenter.
