5 KVA to 10 KVA Automatic Voltage Stabilizer Circuit – 220 Volts, 120 Volts

The diagram shows a rather simple voltage stabilizer design which can hold huge output power in the order of 5 to 10KVA. The use of SSR or solid state relays makes the output stage easy to configure and very accurate – thanks to the modern SSRs which are designed to trigger massive power in response to smaller input DC potentials.

The proposed circuit of a simple 5 KVA to 10 KVA automatic voltage stabilizer circuit is easy to understand. All the opamps are arranged in standard voltage comparator modes.

The presets P1 to P7 can be adjusted as per the required tripping points, which will correspond to the output SSR switching and the subsequent transformer tap selections.

The central green TAP is the normal voltage output, the lower TAPs gradually produce higher voltages while the upper TAPs are set for lower voltages.

These TAPs are chosen by the appropriate SSRs in response to the varying AC voltages, thus adjusting the output voltage to the appliances close to normal levels.

This circuit was asked by Mr. Alexandar and the SSR data was provided by him.

Parts List

R1 to R9 = 1K, 1/4 watt,

P1 to P7 = 10K preset,

C1 = 1000uF/25V

VR1 = 1K Preset,

opamps = IC 324,

Transformer = Input 230volts or 120volts, Taps – incrementing/decrementing voltage levels (TAPs) as per individual specs.

SSR = 10KVA/230volts = output, 5 to 32 volts DC = input

Full circuit diagram of the proposed A Simple 5 KVA to 10 KVA Automatic Voltage Stabilizer Circuit @220 Volts, 120 Volts

5 KVA to 10 KVA Automatic Voltage Stabilizer Circuit - 220 Volts, 120 Volts

SSR Image

74 Replies to “5 KVA to 10 KVA Automatic Voltage Stabilizer Circuit – 220 Volts, 120 Volts”

  1. Can you please tell me the ordering spec for transformer. Say my requirement is around 8KVA
    (Around 35Amps). How do i explain the spec to a tyranny maker- is it like primary 230VAC and secondary is 160 to 300vac and 35Amps (8KVA). Thanks

    1. The transformer is an auto-transformer which is switched automatically by the relay contacts depending upon the settings and the input voltages.

      The voltage range may be applied by choosing an appropriate auto transformer matching the required specs.

  2. Goodday sir. Am still new to electronics. I like this project, and want to do it. My questions are (1) what was your set value of VR1 (1k), P1-P7 (10K) for the relay to switch automatically? (2) what are the number of turns of each tap of your transformer where the seven SSR is connected.

  3. Sir, i understood the circuit. I have built an inverter and battery charger before. I can wind transformer and i want to try your circuit. I want to learn more practically, that was why i want to know the number of turns and corresponding voltages for each loop of the transfo. And your set resistance value of VR1 and P1-P7 so that it will be easy for me to build it. I intend constructing AVR in my final year, 2013. Please, Sir i need your help

    1. The transformer will need to be procured readymade or specially ordered with desired voltage taps.

      All preset needs to be adjusted while setting up the circuit, it's values are never fixed so cannot be predetermined.

      You will have to first learn about how opamps are used as comparaters before making this circuit.

    2. A 50 hz mild steel plated core is defined else where. For transformer winding you may require 2.7 turns arorund core per volt both in secondary and main winding. The wire gauge will depend on current rating both in primary and secondary.The core diameter shall be sufficient that magnetic flux during operation shall not reach saturation
      It is my obtained knowledge. Better consult designers on requirements of core area and dia of innsulated copper wire for the desired power transfermation.As it is 2.7 turns per volt is the winding requirement.

  4. Hi Swagatam, I built this circuit and it switches very fine but i have a challenge of often burnt out SSR. First i blamed it on conterfeited component until i used a fairly used original SSR. I was faced by the same problem. what do you suggest i do? . this is a 15kva unit and 75A SSR was used. It got burnt even without load when transiting.

    1. The transition zone might be causing the problems, at this zone two adjacent SSRs might be conducting together for a fraction of a second causing a possible short circuit across their AC connections.

      Connect a zener diode, may be 6V zener at the outputs of all the opamps, so that the inputs of the SSRs receive the triggering voltage a shade later, after the relevant opamps have switched completely.

      I hope this works.

  5. hello Swagatam, I built this circuit and it switches so fine and accurately but the problem lies on often burnt out or short circuit ssr @ transition from one voltage lever to another.A 75A ssr was used. Even without a load i often get a burnt out relay when switching. i know my setting are okay. So what do i do.

    1. Hello Dear Swagatam,
      I did it as suggested putting 6V zener diode in series with the 1k resistors, i realize the SSR was not switching then, i changed it to 3V each they started switching only for the last two low voltage side that did not switch on 3V zener ,I furtherly reduced those two Zener to 2.2V and it worked. And not burning my SSR as before now. That Transition zone between two SSR can't it be totally separated because i experience a vibration in my gadget when in that zone.

    2. You may replace the zeners with RED or Green LEDs, this will effectively isolate the transition zones, and also will provide useful indications regarding the switching conditions……

    1. the lower taps are rated with gradual increasing voltages while the upper taps are rated with gradual reducing voltage. The voltage selections will depend on your specific needs.

  6. Dear sir
    thanks for your wonderful explanation
    can u please explain how to design stabilizer transformer of 500 w its turning and taps etc if possible can explain general guidelines to design stabilizer transformers it will be very helpful

  7. Hello
    It is nice blog I need to make automatic voltage stabilizer. my power consumption around 5kw, and AC input extremely vary from 120 -200v but I need regulated 220 -240v any body please help me?

  8. Hello your part list means
    Resistor = R1 to R9 = 1K, 1/4 watt,
    Variable resistor/Trimmer =P1 to P7 = 10K preset, i have only variable 10k
    electrolytic capacitor = C1 = 1000uF/25V
    variable resistor = VR1 = 1K Preset,
    is it opto copler opamps = IC 324,
    Transformer = Input 230volts or 120volts, Taps – incrementing/decrementing voltage levels (TAPs) as per individual specs.
    SSR= I have only SSR Trigger Current: 7.5mA/12V, Control Voltage: 24-380V AC,Input Voltage: 3-32V DC yours = 10KVA/230volts = output, 5 to 32 volts DC = input

  9. Hello yonder. I really appreciate your website. Well, I'm currently designing this particular circuit and when I'm through, I'll love to put together my experience, pcb, modified circuit and the final assembly together so as to contribute in my little way. Thanks for the good job.

    1. Hello yonder, I met unexpected things today as the input vdc of the SSR is 10-32VDC. I'm afraid if the signal output of the LM324 will be able to drive it successfully. Please, can you share with me any modifications. Thanks.

    2. Hello yonder, the opamp outputs will always generate a voltage that may be equal to the supply voltage…so 10V may not be an issue if the supply voltage to the IC is 12V

  10. Dear Sir.
    In the beginning I would like to thank you for your efforts to enrich the science and really appreciate your website, God bless you
    Do I hope to send the final proteus design to review the circuit and inform me the mistakes ?

  11. I have a Voltage stabilizer for fridge(Godrej Voltz-500 VA)Which has failed recently.On checking it was found that the Transformer,circuit Board, Relays etc are all found to be fine.Only a IC used for 7-segment display has failed.Can this be replaced? I was advised to scrap the stabilizer. I do not want to generate E-waste. Can you help me?.

    1. identifying the exact IC can be difficult unless all the associated parts are traced and investigated….you can simply use an analogue 0-300v moving coil type voltmeter for getting the voltage display instead of the digital readout.

  12. Good day Mr Swagatam,am an electronic hobbiest searching for an automatic voltage stabilizer with an input voltage as low as 50v,due to the constant low voltage supply in my area,I will be very glad if you can help me come up with such a circuit. Thank you very much sir as I await your urgent reply.

    1. Hi Musa, you can use the concept which is explained in the above article, you can replace the SSR with relays if required…
      dimension the transformer so that it is able to compensate the 50V low appropriately

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