Solid state relay

Solid State Relay (SSR) is a non-contact 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 end and the load end. The input terminal of the solid state relay uses a tiny control signal to directly drive a large current load.

Solid state relays (SOLIDSTATERELAYS, hereinafter abbreviated as "SSR"), is a new type of non-contact switching device composed entirely of solid-state electronic components, which use the switching characteristics of electronic components (such as switching transistors, triacs and other semiconductor devices) , Can achieve the purpose of making and breaking the circuit without contact and spark, so it is also called "non-contact switch". The solid-state relay is a four-terminal active device, two of which are input control terminals, and the other two terminals are output controlled terminals. It has both amplifying driving function and isolation function, which is very suitable for driving high-power switching actuators. Compared with electromagnetic relays, it has higher reliability, no contact, long life, fast speed, and small interference to the outside world. It has been widely used.

What is the advantages:

(1) Long life and high reliability: The solid state relay has no mechanical parts, and the contact function is completed by solid devices. Since there are no moving parts, it can work under high impact and vibration environments. Because of the components that make up the solid state relay The inherent characteristics of solid state relays determine the long life and high reliability of solid state relays.

(2) High sensitivity, low control power, and good electromagnetic compatibility: The solid-state relay has a wide input voltage range and low drive power, and is compatible with most logic integrated circuits without the need for buffers or drivers.

(3) Fast switching: Because solid-state relays use solid-state devices, the switching speed can range from a few milliseconds to a few microseconds.

(4) Small electromagnetic interference: The solid state relay has no input "coil", no arc ignition and rebound, thus reducing electromagnetic interference. Most AC output solid state relays are a zero-voltage switch, which is turned on at zero voltage and turned off at zero current, reducing the sudden interruption of the current waveform, thereby reducing the switching transient effect.

Installation:

Horizontal W type, vertical L type, small size, suitable for direct welding and installation of printed boards. Vertical L2 type, not only suitable for circuit board welding installation, but also suitable for circuit board plug-in installation. When selecting solid-state relays used on printed circuit boards with low current specifications, since the lead terminals are made of high thermal conductivity materials, the soldering should be carried out under the conditions of a temperature less than 250°C and a time less than 10S. If the surrounding temperature is considered, if necessary Derating can be considered. Generally, the load current should be controlled within 1/2 of the rated value.

K-type and F-type, suitable for radiator and instrument bottom plate installation. When installing high-power SSR (K-type and F-type packages), pay attention that the contact surface of the radiator should be flat and coated with thermal grease (MEBO T-50). The greater the installation torque, the smaller the contact thermal resistance. High-current lead wires need to be equipped with cold-pressed welding lugs to reduce lead wire contact resistance.