Electronic Tap-Changing Solid-State Stabilizer

Hi Onesmo,

I think that it will not be possible to provide 230V exactly. What should be the tolerance on output voltage? +/- 10V? If so you will require 19 taps and 19 triacs to supply them.

Its true zodiac.

I know for sure its had to get exactly 230V.Am wishing to design a stabilizer of at least 230V +/- 2%. This means I expect 230V +/- 5V output voltage.

Am looking forwad on how I can control my thyristors(3),between three decitions.

below -exactly - over.

Hello Onesmo,

Being a Mechanical Engineer graduated in the sixtees, my knowledge in Electrical engineering / Electronics is premitive. You may be better off consulting some one who is familiar with programmable micro chips.

You may use a 18 V transformer to power your electronics. I suggested 18 V since your voltage variation is too much. The secondary voltage will be from 10.6 to 25.2V, when rectified you will get 13.6 at the low end and 34.2 V at the high end considering two diode drop.

Branch the out-put directly at the bridge to two diodes so that the voltage variation on one branch will not be seen on the other. Use a heavy, 50 V electrolytic capacitor for the supply branch and a small one, may be 1 micro F tantalum on the other with a 200K potential divider across it. This will give you the referance voltage that you need.

Two voltage regulators, a 12 V one for opto-couplers (Use MOC 3083) and a 5 volt one for the micro-chip circuit.

Set the potential divider such that the output voltage is 4 VDC when when the AC input to the transformer is 322V (Make sure that you use a custom transformer with a primary voltage of 322 VAC and secondary 25 VAC). As the input voltage varies this voltage varies and let this be the Vref to the micro-chip. Program the chip in such a way that the outputs will go Low one at a time depending the input voltage. Make sure that there must be a dead period between switchings, at least 20 milli seconds, to ensure that adjacent taps are not shorted during transition.

Since the load is inductive, use Hi-commutation triacs with very high breakdown voltage.

I am certain that you know how to use the triacs and optocouplers in the circuit. It will be a good idea to use an NTC devise in series with both supply leads and an MOV in parallel with the output.

Good Luck!

Job Thykkoottathil.

Thanks very much for your nice ideals I hope they will help me in a wide range.

I think it is a nice ideal to use a PIC chip to switch in Different levels depending on the input value,also I like the point that I should make the upper value 322V (AC) equet to 4V (DC) as my reference.Farther more am not afraid of programing chips since I think I have enough programing skills to carryout simple chip programing e,g micro C and C++.

On other hand sometimes these chips are expensive so am trying to understand how to achieve my control using normal voltage comparators using op amps (LM 339/LM 393).This means its just a matter clear understanding both alternative.

Hope to get something on how to do the same operation with voltage comparators.

sounds like homework to me.

Dear guest,

Home work or not, the guy asked for help. It sounds that you may have the knowedge. If so please help him.

Thanks.