Solid-state relay (SSR) is an all-electronic circuit combination of components, solid-state relays rely on semiconductor devices and electronic components of electromagnetic and optical characteristics to complete its isolation and relay switching functions. Compared with traditional electromagnetic relays, solid-state relays are relays that have no machinery and no moving parts, but have essentially the same functions as electromagnetic relays.
Solid state relays are widely used in industrial automation control, such as electric furnace heating system, mature control machinery, remote control machinery, motor, solenoid valve and signal lamp, flicker, stage lighting control system, medical equipment, copier, washing machine, fire security system and so on have a large number of applications. Reliable operation, no contact, no spark, long life, no noise, no electromagnetic interference, fast switching speed, with a small control signal to achieve the purpose of directly driving large current load.
What is the difference between solid state relays and ordinary relays
Due to the different trigger signal mode, the difference between zero-crossing type and random type mainly lies in the different conditions of load AC current conduction. When an effective control signal is applied to the input, the load output of the random LSR is switched on immediately (at a speed of microseconds), while the load voltage of the zero-crossing LSR is switched on only when the load voltage crosses the zero-crossing region (about ±15V). When the control signal is withdrawn from the input, both zero-crossing and random LSR are turned off when the current is less than the maintenance current, and the turn-off conditions of the two types are the same. Although zero-crossing LSR may cause the maximum half-cycle delay, it reduces the impact on the load and generates RF interference, and can obtain a complete sinusoidal waveform on the load, becoming an ideal switching device, which is most widely used in the "single-pole single-throw" switching applications. The LSR is characterized by fast reaction speed, and it can easily change the AC working voltage of the load by controlling the phase-shift trigger pulse, so that it can be applied to precisely adjust the temperature, dimming and other resistive loads and some inductive loads.