Basically, there could be two type of phase changing device, one could be an automated one with a digital numeric relay for automatic change over and the another one is a basic manual one which have to be operated by a human.
For typical domestic use, the device illustrated bellow have two more identical units mounted over a board with some indications regarding the number of phase available and the currently applied change over status.
The red, yellow and blue indicating lights will be in two sets in which the first set will be pointing towards the availability and healthiness of all the respective three phases at the incoming side of the device. By looking at these indication, one can determine that out three phases, which phase is available.
Similarly the second set of indication lamp is showing the status of the three phases at the outgoing end of the device (Which will be the actual status of the three phases being fed to your home).
whenever there will be an phase outage due to faults or blown fuses at the power distribution feeder end, both sets of same coloured indication lamps will stop glowing to which phase they are assigned for (e.g. if only both sets of Yellow and Blue indication lamps are working that implicates that power supply to Red phase have been disrupted).
And now comes the part where the actual operation of the phase converter/selector will be done. There would be three similar rotary switches with three/four similar markings on it, so lets pick one switch for ease of understanding. Normally, the following would be the positions of the selector switch, for R Phase selection, the knob on switch will be indicating 1 or R. For Y-Phase, the knob will be positioned on 2 or Y and similar for the 3rd of Y phase.
Suppose the Red indication lamps are not working, but other two are working, then the switched have to be adjusted so that only Y and B phase will be supplied further, hence the R-Phase's knob will be rotated and can be placed on either position number 2 or 3 from its earlier position of 1 so that the power line of R phase is connected to that of Y or B-Phase.
So, when the above mechanism is applied, all the 3 indication lamp on the second set will start working although the one indication lamp on the incomer side is still dark, this shows that the changeover have been completed successfully.
Things to remember !!
For typical domestic use, the device illustrated bellow have two more identical units mounted over a board with some indications regarding the number of phase available and the currently applied change over status.
Similarly the second set of indication lamp is showing the status of the three phases at the outgoing end of the device (Which will be the actual status of the three phases being fed to your home).
whenever there will be an phase outage due to faults or blown fuses at the power distribution feeder end, both sets of same coloured indication lamps will stop glowing to which phase they are assigned for (e.g. if only both sets of Yellow and Blue indication lamps are working that implicates that power supply to Red phase have been disrupted).
And now comes the part where the actual operation of the phase converter/selector will be done. There would be three similar rotary switches with three/four similar markings on it, so lets pick one switch for ease of understanding. Normally, the following would be the positions of the selector switch, for R Phase selection, the knob on switch will be indicating 1 or R. For Y-Phase, the knob will be positioned on 2 or Y and similar for the 3rd of Y phase.
Suppose the Red indication lamps are not working, but other two are working, then the switched have to be adjusted so that only Y and B phase will be supplied further, hence the R-Phase's knob will be rotated and can be placed on either position number 2 or 3 from its earlier position of 1 so that the power line of R phase is connected to that of Y or B-Phase.
So, when the above mechanism is applied, all the 3 indication lamp on the second set will start working although the one indication lamp on the incomer side is still dark, this shows that the changeover have been completed successfully.
Things to remember !!
- Never ever do this change-over operation with your main supply on, in order to avoid a possible flashover, always drop the main MCB of your home before operating the device.
- Never ever use this change over device if you have a direct 3-phase device like flour-mill or water pump of high capacity as the two similar phase will damage the device.
- Always remember to re-position the knobs to its original position once the phase have been restored if the damage caused by heavy flow of current over a single phase have to be avoided.
