Theory:Solid State Relay Usage:General Purpose Size:Miniature Protect Feature:Sealed Contact Load:Low Power Contact material:Silver alloy Electrical life:≥10^5 times Mechanical life:≥10^7 times Ambient temperature:-30~80℃ Ambient humidity:45%~75%RH
A solid state relay (SSR) is a contactless switch composed of microelectronic circuits, discrete electronic devices, and power electronic power devices. The isolation device is used to realize the isolation between the control terminal and the load terminal. The input of the solid-state relay uses tiny control signals to directly drive large current loads.
1.Miniature,light,high sensitivity,long life.
2.Installation method like PCB print layout,Socket type,flange type are avaible.
3.Indicator light and diode are optional.
4.Silver alloy contact, with the features of heat resistance,shock resistance,high flame retardant refractive index, is used to make the casing.
5.Best quality grass and integral punch forming method are adopted,resulting in outstanding conduction.
(1) High lifespan and high reliability: Solid state relays have no mechanical parts, and the solid device completes the contact function. Since there are no moving parts, they can work in a high impact and vibration environment. Due to the components that constitute the solid state relay The inherent characteristics of the solid-state relay determine its long life and high reliability.
(2) High sensitivity, low control power, and good electromagnetic compatibility: The input voltage range of the solid-state relay is wide, and the driving power is low. It is compatible with most logic integrated circuits without the need to add buffers or drivers.
(3) Fast conversion: Because solid-state relays use solid-state devices, the switching speed can be from a few milliseconds to a few microseconds.
(4) Low electromagnetic interference: The solid-state relay has no input “coil”, no ignition arc and rebound, thus reducing electromagnetic interference. Most AC output solid-state relays are a zero-voltage switch that turns on at zero voltage and turns off at zero current, reducing the sudden interruption of the current waveform, thereby reducing the switching transient effect.
The solid state relay is composed of three parts: input circuit, isolation (coupling) and output circuit.
Input circuit According to different types of input voltage, input circuits can be divided into three types: DC input circuits, AC input circuits, and AC and DC input circuits. Some input control circuits are also compatible with TTL / CMOS, positive and negative logic control and inversion, and can be easily connected to TTL and MOS logic circuits. For a control signal with a fixed control voltage, a resistive input circuit is used. The control current is guaranteed to be greater than 5mA. For the control signal with a large change range (such as 3 ~ 32V), a constant current circuit is used to ensure that the current is reliably operated at greater than 5mA in the entire voltage change range.
Isolated coupling There are two types of isolation and coupling methods for the input and output circuits of solid state relays: photocoupling and transformer coupling: photocoupling usually uses photodiodes-phototransistors, photodiodes-bidirectional light-controlled thyristors, photovoltaic cells, to achieve control side and load side Isolation control; high-frequency transformer coupling is to use the self-excited high-frequency signal generated by the input control signal to be coupled to the secondary, detected and rectified, and processed by the logic circuit to form the drive signal.
Output circuit The power switch of the SSR is directly connected to the power supply and the load end to realize the on-off switching of the load power supply. Mainly used are high-power transistor triode (switch-transistor), unidirectional thyristor (Thyristor or SCR), bidirectional triac (Triac), power field effect transistor (MOSFET), insulated gate bipolar transistor (IGBT) . The output circuit of solid state relay can also be divided into DC output circuit, AC output circuit and AC / DC output circuit. According to the load type, it can be divided into DC solid state relay and AC solid state relay. Bipolar devices or power field effect transistors can be used for DC output, and two thyristors or one bidirectional thyristor are usually used for AC output. The AC solid-state relay can be divided into single-phase AC solid-state relay and three-phase AC solid-state relay. AC solid state relays can be divided into random AC solid state relays and zero-cross AC solid state relays according to the timing of on and off.
Solid-state relays have been widely used in computer peripheral interface equipment, constant temperature systems, temperature adjustment, electric furnace heating control, motor control, CNC machinery, remote control systems, industrial automation devices; signal lights, dimming, scintillator, lighting stage lighting control systems; instruments Meters, medical equipment, copiers, automatic washing machines; automatic fire protection, security systems, and power capacitor switch as power factor compensation for power grids, etc. In addition, they are widely used in chemical, coal mines, etc. where explosion-proof, moisture-proof, and anti-corrosion are required .