Solid State Relay (SSR for short) 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 of the control end and the load end. The input end of the solid state relay is used for Small control signals can directly drive large current loads. Next, I will tell you in detail "How to judge the quality of three-phase solid-state relays common faults of three-phase solid-state relays"
How to judge the quality of three-phase solid-state relays
1.A good solid state relay, when there is a signal input, the red LED indicator light is on, and the main circuit is turned on. When the control signal is normal, it is a good way to observe the indicator light.
2.Use a multimeter to measure whether the main circuit voltage is in the normal range when the solid state relay indicator light is on. When the indicator light is off, whether the main circuit voltage is zero.
3.Disconnect the power supply of the solid state relay, turn the multimeter to the ohm automatic gear, measure the resistance value of the solid state relay main circuit forward conduction, the normal resistance value is close to infinity.
4.Observe whether the appearance of the solid state relay is damaged and whether the surrounding environment is good. Whether the terminals are firm and whether the surface is oxidized. Use a multimeter to measure whether the resistance to ground of the solid state relay is close to infinity.
Common faults of three-phase solid state relays
Solid state relays use small signals to control the triac to turn on or off. It has no mechanical parts and usually has a long service life. However, due to its weak overload capacity, its failure is generally caused by overload. Damage:
1. The output is short-circuited, then the contacts of the ordinary relay are burned together, that is, the circuit is always straight;
2. The circuit is open, then, no matter whether there is a signal input, the circuit can never be connected;
3. Small signal If there is a problem in the control part, it will also cause the phenomenon of open circuit or short-circuit at the output end, but this situation is relatively rare.
4. Because the solid state relay is encapsulated with epoxy, it is generally difficult to maintain the device. If it is a relatively expensive high-power one, you can try to repair it. There is no need to repair the low-power one. Just replace it with the same model, or if it is often broken, check the reason. If there are no other problems, you can change a power. Larger, higher voltage replacement.