Zero Crossing Solid State Relay Circuit

A solid state relay circuit with in built zero crossing detector is described in this article.

Zero crossing solid state relay circuit.

Begingroup the solid state relay conducts in both directions positive and negative current just like a mechanical relay when you apply the dc voltage to the control circuit. For the zero crossing ssr relays their switching state of the output circuit. Nov 04 2012 10 03 pm by pepemanuer reason. To the zero crossing function of the ssr.

Zero crossing or burst firing control is an approach for electrical control circuits that starts operation with the ac load voltage at close to 0 volts in the ac cycle. Also known as a synchronous solid state relay this is the most common type of ssr used in control applications. Solid state relay with zero cross circuit nov 04 2012 09 59 pm last edit. This is in relation to solid state relays such as triacs and silicon controlled rectifiers the purpose of the circuit is to start the triac conducting very near the time point when the load voltage is crossing zero volts at.

The downside to ssr is the 1 7v drop across the. Evidence1 has come to light that zero crossover turn on of such loads can cause a surge current of perhaps 10 to 40 times the steady state current whereas turn on at peak voltage results in little or no surge. The circuit is very easy to understand and build yet provides with useful features like clean switching free from rf disturbances and able to handle loads up to 500 watts we have learned a lot about relays and how they function. 1 zero crossing ac solid state relays figure 4 2 are also known as zero crossing trigger ac solid state relays zero cross turn on solid state relay zero switching ac solid state relays zero voltage ac solid state relays or synchronous ac solid state relays.

So when you apply a control voltage the relay waits until a zero crossing and closes and remains. 1 is posible use this ssr for pwm speed control of ac motor directly. So the zero crossing circuit is used to turn them on at zero crossing instead of in the middle of the cycle which would cause a spike to a motor. The solid state relay turns off when the load current is at the zero crossing point of the ac load current sine wave.

The zero crossing only refers to when the switch closes or opens. A zero crossover solid state relay may be the worst possible method of switching on a transformer or a highly inductive load. This is a characteristic of all ac output solid state relays regardless of the switching type.