How AC voltage stabilizer works

[Mrunal Ahirrao]

Hi one and all,
I am studying AC voltage stabilizers and I have got good info on internet. but I didn't got any basic information regarding how a auto transformer tappings can be connected/disconnected to increase or decrease mains AC voltage. I have got a auto transformer with 3 tappings 160V,180V and 250V. But i am confused regarding connection of these tappings with mains AC voltage to increase or decrease voltage.I have seen this connection diagram on one blog but I didn't understood how it will stabilize voltage. Any help would useful.

 

[chuckey]

As shown if RL4 closes then the input goes to the 160V tap and the output comes from the 240V. if the mains voltage rises, RL1 changes over and the input is applied to the 190V tap. if the mains rises more RL3 changes over and the input goes to the 215V tap.
RL4 is a safety relay, it should only be closed when all the other relays have finished switching. If you switched the unit on without it, the incoming mains, which should be 230V would be applied to the 160V tap so the output voltage would be 240/160 X 230 ~345 V until RL1 switched over.
Frank

 

[Mrunal Ahirrao]

if input goes to 160V tap but its not reflected on output

 

[betwixt]

The ratio of turns on the transformer between input and output windings is what decides the voltage. Something else not shown on the diagram has to monitor the voltage and operate the relays so the input voltage is routed to the appropriate transformer tap.

RL1, RL2 and RL3 route the input voltage to one of the taps and at the same time route another tap to the output point. Operating the relays in different combinations will give different output voltage for a fixed input OR looking at it the other way, will give a fixed output for a varing input.

RL4 is to isolate the output until the other relays are in the correct state, if it wasn't there it would be possible to output a wrong voltage in the period before the monitor had controlled the other relays.

Brian.

 

[D.A.(Tony)Stewart]

This is basically an auto-transformer with 2 relays to choose 3 input taps and 1 relay to select either of 2 taps to give - 6 combinations of voltage ratios ,
- 4 combinations to boost,
- 1 combo to reduce line voltage
- 1 combo on 1:1 (240V tap)
- 1 relay just enables the output

you figure out the ratios.

Does this look more logical?

 

[Mrunal Ahirrao]

Thanks all of you I have understood it now.