Key switch refers to the use of buttons to promote the transmission of the organization, so that the dynamic contact with the static contact or disconnect and end the circuit switching switch. The key switch is a simple layout that uses a very wide range of main electrical appliances. In the electric active control circuit, uses in the manual announces the control signal to control the contactor, the relay, the electromagnetic starter and so on. Key switch can end start, stop, positive rotation, speed and interlock and other fundamental control. Usually each key switch has two pairs of contacts. Each pair of contacts is composed of a constant open contact and a constant closed contact point. When pressing the key, the two pairs of contacts move together, often close contacts disconnect, often open contact closed.
The principle of key switch
Key switch AC power input through rectification filter into DC, after High-frequency PWM (pulse width modulation) signal control switch tube, the DC added to the switch transformer primary; Switching transformer secondary induction of high-frequency voltage, rectifier filter supply load; Some of the output is fed back to the control circuit by a certain circuit to achieve the intention of stable output. Key switch is a relatively complex layout of a switch, its components include handles, skateboards, contacts, terminals, and so on. Key switch operation is made by the key to some conduction to the handle, handle and then control the contacts and terminals, the closure of the contact point control. The key switch can be divided into single button switch and multi-key combination button switch. Key switch has one-touch and multiple-key combination of two types. Single-key switch is usually used in the TV as a power switch, it is divided into self-locking self reset (this switch is connected to the lock, then click the Reset) and no lock type (can not be determined, press when connected, after the reset) two kinds of layout. Toggle switch Multi-key combination button switch is divided into self-locking, interlock and no lock and other layout types. Eight-key or 12-key switch in the early stage for the TV program preselection switch, four-button switch in the early stage of the wave wheel type washing machine to choose switch.
Function of key switch
Key switch and toggle switch on the use of data, in the flame retardant, insulation, impact resistance and moisture resistance are very good, raw materials stable and strong, not easy to change color. Today's switch panel in addition to the selection of high-grade plastic, there are gold-plated, stainless steel, copper and other metal raw materials, for everyone to provide more and more selection. Key switch in the use of household electrical is very wide, one-touch button switch is often used as a TV power switch, and the multi-key combination of key switches used as the old TV program selection switch, and the early washing machine in the condition of selection switch. Mainly used in industry and some household appliances, such as televisions, color TV, computer, CNC machine tools, active control equipment and other applications.
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