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By Abdul Afram, Abdul Atisam Farooq
Keywords: Generator ATS, Generator ON/OFF controller, Grid power monitoring, Load shifting.
Due to the power crisis in Pakistan there is a growing market of small household generators ranging from 2-3 KVA which can handle the load of a small house comprising of a few fans, lights, a computer and a TV. These generators are cheap and come equipped with a self-start mechanism built into the generator. On the push of a button, the user can start the generator easily. In the cities, normally these generators are used for a short period of time when the power from the grid is not available. When the power from the grid is not available the user starts the generator and connects the load to the generator manually. When the power from the grid becomes available, the user disconnects the generator from the load, turns off the generator and connects the load to the grid manually. Normally this function is performed manually and requires the engagement of the user for turning the generator on and off and shifting the load between the generator and the grid. In this paper we propose a controller which performs these tasks automatically. The controller monitors the grid voltage and when there is no voltage, the controller disconnects the load from the grid, starts the generator and shifts the load to the generator. The controller keeps on monitoring the grid voltage and when it comes back on the system turns off the generator and transfers the load to the grid. This system is very useful in the high rate of power failure crisis occurring in Pakistan and relieves the user from the tedious task of attending to the generator regularly for continuous availability of power. There are some commercially available systems in the market which cost even more than the price of a household generator and hence are not economical for the users of household generators. In this paper we propose a very low cost system which can be built using the commonly available components such as relays, timers, transformers, diodes and capacitors. This controller does not require any programmable components such as microcontroller, FPGA, DSP etc. to perform its function. The number of components is kept to minimum to increase the reliability of the system.