Monday, November 7, 2011

Switch between Offgrid inverter and gridtie

This power strip has building automatic switch between offgrid power and gridtie power.

When i turn on this power strip it automatically detects lowvoltage on tofgrid batteri'es, and chose to turn on the inverter or switch on relay to grid as power source. Also, if low voltage is detectected when i watch television, i switch to grid from offgrid, an stay gridtied to next time power strip is turned on.

To stay safe it has build in two optocouplers, to protect agains 220 volt in the 12 volt offgrid system.

Schematic:

Link to the under-voltage detector circuit


The control circuit on pcb: 


This is how i works:



Be careful, there is danger of electric shock, and at worst you can die from it. I myself disclaims any responsibility for your experiments.


In some countries it is not allowed to work with diy stuff connected to the grid, and other things connected to the gridIn some countries there is some national wiring regulations to be observed.





The idee in blocks



My 12 volt to 220 volt inverter:





The power strip and the inverter



I tryed to yúse a simple Set / reset flip flop with transistors, to hold relay, but it was unstable, so i desided to use a small relay with low power consumption instead. You can try to build this circuit to experiment with transistor based set reset logic:

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