Solid State Relay Switches
Solid state relays have features which electromechanical relays do not, such as:
Shock and vibration resistance
Generation of RFI, EMI
No contact bounce
Zero voltage switching
Immunity to humidity, salt spray and dirt
A relay is an electrical switch that opens and closes automatically under control of another electrical circuit. An important function of any relay is isolation between the control circuit and the controlled circuit.
Traditional relays were electromechanical devices in which a solenoid was used to pull-in a set of switch contacts. The vast majority of relays are simple, unintelligent devices that simply conduct load current when an input voltage is above some switch threshold.This produces switching noise, at a minimum, and will also produce pitting and erosion of the contacts. Another major drawback of the electromechanical relay is an inherently short life relative to that of solid state devices.
A solid state relay provides isolation between a control circuit and a switched circuit. It has all solid state components, and do not require any moving parts. A solid state relay has many advantages over electromechanical relays, such as increased lifetime, clean, bounceless operation, decreased electrical noise, compatibility with digital circuitry, and resistance to corrosion.