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Why Choose the Solid State Switch?

Understanding Solid State Switch

A relay is an electric switch that uses a low-power signal to control high-power devices. Relays control a circuit by switching contacts in the control circuit, usually without directly switching the load. Compared to electromechanical relays, solid state switch has many important advantages because it doesn't have any moving parts. These advantages can be summarized into seven key factors: simple design, long life, low power consumption, fast switching speed, quiet operation, low electromagnetic interference (EMI), and suitability for harsh environments.

Reasons for Choosing the Solid State Switch

  • Simple design: The circuit board size and overall volume of the solid state switch are much smaller than those of EMRs of similar specifications. Solid state switch can also be up to 70% lighter than electromechanical relays, depending on their power requirements. The size and weight advantages make solid state switches ideal for embedded systems, saving valuable installation space.

    Because solid state switches operate regardless of position, they are suitable for installation in either a vertical or horizontal position. Certain solid state switches have housings with rotation-preventing barriers. Although they are smaller in size, solid state switches are not inferior to electromechanical relays in terms of function. Optocouplers completely isolate the relay circuit, eliminating high-voltage failures.

  • Quiet operation: Solid state relays use electronic circuits to provide switching. Since they have no moving parts, they have completely silent switching operations. This is a very desirable characteristic in various commercial and medical applications.

  • Minimal EMI: Low-noise solid state switch provides zero-voltage turn-on and zero-current turn-off, reducing electromagnetic interference (EMI) to negligible levels. Zero-crossing switching is one of the most important advantages of the solid state switch. This function closes the AC load when the sine wave current is zero, eliminating problems such as arc and electrical noise. Even if the input control signal is removed, the switch device will continue to conduct until the current drops below its threshold.

    This is why solid state switch will never turn off the load in the middle of the sine wave peak, which is particularly important for inductive loads, where there might be large voltage spikes. The zero-voltage turn-on and zero-current turn-off functions minimize the electrical interference generated by solid state switch. These zero-switching relays are the most widely used type of relay.

  • Ideal choice for harsh environments: In industry, the characteristics of harsh environments include temperature, dust, humidity, vibration, and mechanical stress. Because solid state switches have no moving parts and are completely enclosed in their housings, they are very suitable for harsh environment applications. Additionally, solid state switches do not produce sparks during operation, making them suitable for explosive environments. External magnetic fields have negligible impact on the solid state switch.

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