Integrated solid state relay


Posted on Sep 5, 2012    3740

A complete zero-voltage switch solid-state relay contains an input circuit, an output circuit, and the power thyristor. The circuit illustrates a triac power thyristor with snubber circuit and GE-MOVRII Vans tor transient over-voltage protection. The 22 ohm resistor shunts di/dt currents, passing through the bridge diode capacitances, from the triac gate, while the 100 ohm resistor limits surge and gate currents to safe levels. Although the circuits illustrated are for 120-V rms operation, relays that operate on 220 V require higher voltage ratings on the MOV, rectifier diodes, triac, and pilot SCR.


Integrated solid state relay
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The voltage divider that senses zero crossing must also be selected to minimize power dissipation in the transistor optisolator circuit for 220-V operation.




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