Inverter/Mains AC Changeover Circuit Using Triacs

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

 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.

Need Help? Please send your queries through Comments for quick replies!


afam nzoiwu said…
please i wish to make a request. my genset output is 220v 35Hz. is there any circuit that will correct the output to 220v 50Hz. thanks
afam nzoiwu said…
honestly i love the way u explain things that is why i come here to seek solution. i will try this circuit later bcos i love it.
Swagatam said…
thank you Afam, I appreciate your thoughts,

for adjusting the frequency you will probably require a VFD circuit as given below:

however this circuit could be quite complex and will require an advanced knowledge regarding the subject.
afam nzoiwu said…
hello swagatam, what are the watts of those resistors? about the triac' pins, pin1 is A1-down vertical one. pin2 is A2-upper vertical one. pin3 is G-bended one. am i right? i used BTA41 but one to inverter phase and BC547 got damaged. should i use BT136?
Swagatam said…
hello afam, with printed side of the triac facing you, the right most lead corresponds to the bent lead, the center lead corresponds to the appliance lead, and the left most lead goes to the mains. The BTA41 is more powerful than BT136 so if it blew then BT136 will also get burnt

make sure you do it by understanding the everything correctly and convincingly.

afam nzoiwu said…
should i make all resistors 1watt or 1/2watt?
Swagatam said…
all are 1/4 watt

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