Type and structure of solid state relay

Update:29-11-2019
Summary:

Because solid state relays have no mechanical contacts […]

Because solid state relays have no mechanical contacts and other mechanical parts, their reliability is very high. The solid-state relay does not generate electric sparks and has no noise at the moment of on and off. Its switching speed is quite fast and the operating frequency is also quite high.

Type of solid state relay:
According to the load power it controls, there are AC solid state relays and DC solid state relays. AC solid state relays include: ordinary solid state relays, enhanced solid state relays, European-style relays, etc., which can control the on and off of AC load power. The output switching devices are mostly bidirectional thyristors. The DC solid state relay can control the on and off of the DC load power supply, and its output switching devices are mostly high-power thyristors.

Structure of solid state relay:
The solid state relay is composed of two parts: the input circuit and the output circuit. The input circuit is a photo coupler, which can isolate and control. The output circuit consists of a trigger circuit and a switch circuit. When the light-emitting diode of the light fuser is not energized, the switch output circuit is in an off state. When the light-emitting diode is turned on and emits light, the light fuse circuit outputs a signal, which is amplified by the trigger circuit , So that the switching element of the output circuit reaches a saturated conduction state, thereby completing the on and off of the load circuit.