Although solid-state relays are not as popular as electromagnetic relays, they are also commonly used electrical devices. They are both relays. What are the differences? Let’s talk briefly today.
Electromagnetic relay is an electronic control device, which plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit. It is generally composed of iron core, coil, armature, contact reed and so on.
Compared with electromagnetic relay, solid state relay (SSR) is a relay without mechanical movement and no moving parts, but it has essentially the same function as electromagnetic relay. SSR is a non-contact switching element composed entirely of solid-state electronic components. It uses the electrical, magnetic and optical characteristics of electronic components to complete the isolation of input and output. It uses high-power transistors, power field effect transistors, and one-way controllable The switching characteristics of devices such as silicon or triacs can achieve contactless and spark-free connection and disconnection of the controlled circuit. The solid-state relay has high agility, low control power, relatively long life, good reliability, and the switching speed can reach several milliseconds to several microseconds. 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. Because the tube pressure drop is large, the power consumption and fever after being turned on are also large. The volume of the high-power solid-state relay is far greater than that of the electromagnetic relay of the same capacity, and the cost is also higher.
The use of solid-state relays can make the system have higher performance, but the expensive price causes the cost of the product to rise. Therefore, when the requirements for system performance are not very high, but for products that are very cost-sensitive, use cheap ordinary electromagnetic relays. Controlling the electric heating wire has become the focus of solving the cost problem.