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

In this article we discuss an easy to build a 7 stage high wattage in the order of 5000 to 1000 watts stabilizer circuit which can be used  for controlling our mains AC line fluctuations and for producing very accurate stabilized voltage outputs for our domestic electrical appliances.

Circuit Operation

The proposed Accurate 7 relay OpAmp Controlled Mains Voltage Stabilizer  Circuit concept is rather very simple. It uses discrete opamps wired up as comparators to sense the voltage levels.

As can be seen in the diagram, each opamp's inverting inputs are provided with sequentially incrementing voltage reference levels through a series of presets which drops a certain amount of voltage across itself.

Each opamp compares this voltage with the common sample mains AC voltage level supplied to the opamps non inverting inputs.

As long as this sample voltage is below the reference level the respective opamps keep their outputs low and the subsequent transistor relay stages remain inactive, however in case the voltage levels tends to shift from its normal range, the relevant relays trigger and toggle the transformer taps so that the output is appropriately equalized and corrected.

For example if the input AC voltage tends to fall, the upper relays may get triggered connecting the relevant higher voltage taps with the output and vice versa in case the voltage shoots upwards.

Here the opamp output inter-connections makes sure that only one optocoupler and therefore only one relay gets activated at a time.

Parts List

P1---P8 = 10 K Preset,

A1---A8 = IC 324 (2 Nos)

R1---R8 = 1 K,

All diodes = 1N4007,

All relays = 12 volts, 400 Ohms, SPDT,

Opto Couplers are all = MCT2E or equivalent,

Transformer = Pink Tap is normal voltage tap, the upper taps are in the decrementing order of 25 Volts, while the lower taps are in the incremental order of 25 volts.

Full circuit diagram of the proposed Accurate 7-Stage OpAmp Controlled Mains Voltage Stabilizer.

IC LM324 Pinout Details

Circuit Diagram


7 relay voltage stabilizer circuit


Upgrading into a Solid State Version using SSR

The diagram below shows a rather simple voltage stabilizer design which can hold huge output power in the range 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.

Circuit Description

The proposed circuit of a simple high capacity 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

Solid State SSR Voltage Stabilizer Circuit Diagram


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


SSR Image



About the Author

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials. If you have any circuit related query, you may interact through comments, I'll be most happy to help!

20 thoughts on “5 KVA to 10 KVA Automatic Voltage Stabilizer – 220 Volts, 120 Volts”

  1. Howdy, Friend! Interested to Learn Circuit Designing? Let's Start Discussing below!
  2. Hi my boss swag, this is kaluya moses from Uganda your old student / a follower.
    Honestly, thank you for the wonderful job you doing to serve the world electronically God bless you . long live swag.
    In fact price of electronic mr swag , I will would like to help me the type of sort ware you use to design or to make schematic diagrams/PBC.

    • Thank you Kaluya, I am glad you are liking my website! I use Corel-Draw for designing the schematics and PCBs.

      • Thanks a lot prince of electronics mr Swag, I still need much support from you because i have circuits to design and if at all I need someone to do it for me, what should I do? before I learn to do it myself. please advise me mr Swag. Thanks.

        • Thanks Kaluya, There are probably many PCB softwares online which you could try, but without learning them it could e difficult. Or you may be you can contact a PCB designer for the job.

  3. Hello Dear Swagatam, Please can you guide me on how to setup the two opamps (lm324) for ensuring appropriate shooting/kicking of the relays without crash. Again, at what DC equivalent of 220VAC do I keep the pink (220VAC) tap swiched ON while other stay OFF and vice versa? Please help. Thanks.

    • Hi Kingsley, you just have to adjust the presets from bottom to the top in an incremental order, such that the lowest relay activates at the lowest voltage threshold, the second lowest at the second lowest threshold and so on until the top preset which activates the topmost relay at the highest voltage threshold..

      The lowest threshold could be 150V, and the highest could be 300V.

    • Thank You very much my dearest electronics mentor! I sincerely do appreciate your effort towards keeping young electronic hobbyists updated. I will try the setup and get back to you with observations.

      Thank You once again.

  4. hi swag.please help me with the diagram of electrical series testing board and how to use it.i think it is advisable when testing any short circuit problem.i saw it in youtube but i don’t understand hindi/urdu.thanx

    • Hi Dennis, for testing an electrical system where a short circuit could be possible, the best technique is to use a lamp in series with the supply. For example you can use a 100 watt series bulb and then freely test the system, if at all a short circuit happens, the bulb will light up preventing any kind of burning or fire hazard issues. This is the most basic idea for safely carrying out a short-circuit prone experiment, if your system is more complex or require a more sophisticated cut off system, then please specify your experiment I’ll try to solve it for you.

  5. hi swag,
    what kind of transformer to use?
    how many Ampere to meet 5kva – 10kva?
    or just only any transformer do well?

    • Hi candra, you will need a transformer which may have a 220V or 120V entry and several outputs producing higher than 220V/120V values in steps, and also lower values than 220V/120V in steps. you will have to contact a professional transformer designer and make to order it or try acquiring readymade from ebay or amazon.

      for getting ampere, divide the wattage with the input voltage

  6. Sir,
    Can you explain igbt based static voltage stabilizer with DSP control popular nowadays.If possible please post a circuit of it.

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