The post explains how to make a simple triac based solid-state Inverter/mains AC changeover circuit, the idea was requetsd by Music girl.

Technical Specifications

I would like to replace the SPDT relay with 2 scr's. Would you consider a circuit to replace those changeover relays?
I believe a relay would need to handle 60 amps to be effective for the inverter side... and a smaller SCR for the Charger side.

Many thanks for the great work you do

Inverter/Mains AC Changeover Circuit Using Triacs

 The Design


The functioning of the above shown triac based solid state inverter mains changeover circuit may be understood with the help of the following points:

Assuming mains grid AC to be present:

1) The battery charger section is in the active state and charging the battery.

2) The DC from the charger supply keeps T2 and the triac TR2 switched ON.

3) TR2 allows the load to get the mains supply voltage from the mains AC source.

4) T2 keeps triac TR1 and T1 switched OFF, disabling the battery supply to the inverter and cutting-off the mains entry from the inverter to the load respectively.

5)  In an event when mains AC fails, T2 and TR2 switch OFF giving rise to the following conditions.

6) T1 connects the negative of the battery with the inverter circuit, quickly switching it ON.

7) TR1 makes sure that AC generated by the inverter is instantly allowed to pass to the appliances ensuring an uninterrupted changeover from the AC mains to the inverter mains through the relevant switching of the triacs.

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