Simple automatic change over circuit for homes and work places.
Change overs are required whenever you are handling two or more power from different sources. In homes where inverters or generators are stand by power sources, it is advisable to use a change over system so that when your stand by power is in use, power will not flow into your national power supply.
Also, when change overs are not installed, power will run into your stand by source and destroy it. If its an inverter, all the output mosfets will blow up and even catch fire. Generators may also explode when that happens.
Change overs can be manual or automatic. With manual change overs, u have to wake up from your sleep to change over when your nation grid goes off or when your national grid is restored. Automatic change overs on the other hand does every switching automatically and even connect your inverter for charging.
The circuit is an automatic change over circuit with delay of 20 to 50 seconds, power restored notification alarm and charging port for those who will be using it for inverters.
The circuit is based on 555 timer IC, 220V Contactor, 12V relay, a buzzer, a transformer and few resistors and capacitors.
NOTE THIS CIRCUIT IS NOT FOR NEWBIES. DANGEROUS VOLTAGE INVOLVE. DON'T TRY THIS AS YOUR FIRST PROJECT, YOU CAN DIE.
When National grid is available, the step down transformer, T1 steps the voltage down base on the size of transformer you are using (12V or 24V).
The stepped down voltage is rectified and filtered using D2, D3 and C1.
The voltage regulator, Q4 provides regulated 12V voltage to the IC and all other parts of the circuit.
Because the 555 IC is configured as mono-stable, When the IC receives power, its output (pin3) goes high until time set by R12 and C4 is reached. Until the set delay time will be reached, Q2 will be on and the buzzer alarm will start beeping in short terms.
When the delay time set by R12 and C4 is reached, the output of the 555timer IC (pin 3) will go to zero and the alarm will stop. The zero (0) output provides a negative path for the 12V relay to turn on since it will now be connected to a positive and a negative.
The relay turns on and connect A1 to 220V live to turn the contactor on. When the contactor turns on, the main terminals for the contactor closes and connects the house or load to the national grid. As the main terminals of the contactor closes, the normally close (NC) contacts of the auxiliary on which the inverter or generator is connected opens.
This action ensures that, power from the national grid never meets with the power from your generator or inverter.
Always know that the inverter or generator is connected to the NC contacts of the auxiliary whiles the national grid is connected to the main terminals.
Connect the inverter charger to the charging lines provides in the circuit. This means that, the inverter starts to charge when the nation grid is restored.
LED1 indicates Power in and LED 2 blinks to indicates delay during the sounding of the alarm.
This change over works without your appliances connected as load ever turning off. It even works best when the inverter charger is connected to the circuit.
Change overs are required whenever you are handling two or more power from different sources. In homes where inverters or generators are stand by power sources, it is advisable to use a change over system so that when your stand by power is in use, power will not flow into your national power supply.
Also, when change overs are not installed, power will run into your stand by source and destroy it. If its an inverter, all the output mosfets will blow up and even catch fire. Generators may also explode when that happens.
Change overs can be manual or automatic. With manual change overs, u have to wake up from your sleep to change over when your nation grid goes off or when your national grid is restored. Automatic change overs on the other hand does every switching automatically and even connect your inverter for charging.
The circuit is an automatic change over circuit with delay of 20 to 50 seconds, power restored notification alarm and charging port for those who will be using it for inverters.
The circuit is based on 555 timer IC, 220V Contactor, 12V relay, a buzzer, a transformer and few resistors and capacitors.
AUTOMATIC CHANGE OVER CIRCUIT FOR INVERTERS AND GENERATORS
NOTE THIS CIRCUIT IS NOT FOR NEWBIES. DANGEROUS VOLTAGE INVOLVE. DON'T TRY THIS AS YOUR FIRST PROJECT, YOU CAN DIE.
CIRCUIT OPERATION
When National grid is available, the step down transformer, T1 steps the voltage down base on the size of transformer you are using (12V or 24V).
The stepped down voltage is rectified and filtered using D2, D3 and C1.
The voltage regulator, Q4 provides regulated 12V voltage to the IC and all other parts of the circuit.
Because the 555 IC is configured as mono-stable, When the IC receives power, its output (pin3) goes high until time set by R12 and C4 is reached. Until the set delay time will be reached, Q2 will be on and the buzzer alarm will start beeping in short terms.
When the delay time set by R12 and C4 is reached, the output of the 555timer IC (pin 3) will go to zero and the alarm will stop. The zero (0) output provides a negative path for the 12V relay to turn on since it will now be connected to a positive and a negative.
The relay turns on and connect A1 to 220V live to turn the contactor on. When the contactor turns on, the main terminals for the contactor closes and connects the house or load to the national grid. As the main terminals of the contactor closes, the normally close (NC) contacts of the auxiliary on which the inverter or generator is connected opens.
This action ensures that, power from the national grid never meets with the power from your generator or inverter.
Always know that the inverter or generator is connected to the NC contacts of the auxiliary whiles the national grid is connected to the main terminals.
Connect the inverter charger to the charging lines provides in the circuit. This means that, the inverter starts to charge when the nation grid is restored.
LED1 indicates Power in and LED 2 blinks to indicates delay during the sounding of the alarm.
This change over works without your appliances connected as load ever turning off. It even works best when the inverter charger is connected to the circuit.
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