Wednesday, April 30, 2014

Advantages of Solid State Relays vs. Electromechanical Relays

Solid State Relay
The Future of Load Control is here today in the form of yet another Solid State Device, the SSR or Solid State Relay. Diodes, Transistors, MOSFETS and LEDs have come a long way from their beginnings.

Solid State Relays can be configured to handle high current, high voltage loads with only a small input voltage or current or with just photons for that matter. The use of a Photon Trigger Signal creates a design with zero coupling between the Control Voltage Signal and the Load  Current and Voltage. This can come in very handy when you want to achieve complete isolation between a working load and the control logic circuitry. It also makes for a wide variety of logic control schemes.

Solid State Relays are also much better at controlling inductance loads because of the inherent nature of some of their operating components SCR  ( silicon controlled rectifier ) TRIAC  relay is that they have a natural tendency to open an AC circuit only at a point of Zero Load Current. Because of this an AC current will never be interrupted in the middle of a sine peak. The advantage of this for inductance loads is that it prevents the occurrence of high voltage spikes from the stored energy of the magnetic field in the peak cycle of an inductor. This Single Solid State Relay Advantage alone can save countless dollars of damaged components and man hour repairs.

Some of the more obvious Advantages of Solid State Relays vs. Electromechanical Relays are:

  • Solid State Relays are much faster than Electromechanical Relays
  • SSRs have a far longer working life span the mechanical relays because they have no moving part.
  • Solid State Relays are Safer because they do not produce Sparks when activated. This makes them ideal Load Control Devices in Explosive Work Environments like Dust or Gases.
  • SSRs are much less sensitive to their operating environment factors such as mechanical shock or constant vibration, humidity or external magnetic fields.