facebook you_tube_logo log in

+91 9388 91 0205

Automatic Voltage Controllers for Industrial Use

Effects of Voltage Fluctuation
Advantages of installing SVS
Applications of Servo Stabilizer
Technical Specifications
Description of Servo Stabilizer
Salient Features
Effect of Voltage Unbalancing
Comparison with Dimmer Type
Superior Features of POWER



Power Engineers and Consultants ( Regd.), E-731, Phase VIII, Focal Point, Ludhiana, Punjab - is a group of qualified engineers led by Mr. P.K. Maheshwary who is a degree holder (Electrical Engineering ) of 1972 batch from REC. THE PEC has been in operation in the field of Automatic Voltage Controllers, Servo Voltage Stabilizers, Electroplating Rectifiers, Servo Stabilizers, Anodizing Rectifiers, Electro Colouring Transformers, Distribution Transformers, Isolation Transformers, Variable DC or AC Power Supplies, Rectifier Transformers etc.

The systems are designed and supervised by a team of qualified engineers having more than 39 years of experience to provide best quality equipment leading to total customer’s satisfaction. We have more than 10,000 installations around the country and also exported numbers of equipment to U.S.A., U.K., Africa, Middle East Countries up to 4500 KVA.

Effects of Voltage Fluctuation

Inspite of best efforts, no state electricity board can ensure constant voltage to the customer because of long and inadequate distribution lines and irregular load pattern on distribution transformers. Generally Voltage is low during day time and high during night hours. Moreover on holidays, peak hours, rainy days and when agricultural and industrial load is switched off, the voltage rises sharply which is more dangerous.

This higher current affects the electrical motors (particularly smaller capacity motors up to 7.5 H.P.) in three ways:

  • Higher current produces higher losses in electrical motors which causes premature failure of winding.

  • These higher losses of electric motors also increase the losses of cables, switches, transformers and other associated equipments.

  • For smooth continuous operation of motors, over load relays are usually set at 20% higher setting.

With the installation of the stabilizer and maintaining 390/400 volts, the motor will operate smoothly drawing 15 - 20% lesser current and correspondingly the relay setting can be reduced by 15 - 20%. In case single phasing occurs, the relay will trip in 40 - 50 seconds. The motors can withstand the high current for this period and will be safe. Also, the relays, contactors, switchgears, etc. incorporated with the motor will be safe.

The table below compares the behavior of 5 H.P. motor at different voltages:


7.5 A




11% More

18% More



19% More

28% More



26% more

38% More


The table below compares the behavior of 60 watt lamp at different voltages:



  60 W





  65 W - 8.3% More





  70.6 - 17.6% More





  75.4 - 25.6% More





  83.4 - 39% More



Advantages of Installing Automatic Voltage Controllers

♦ Reduction in breakdown of electrical equipments.

♦ Improvement in power factor.

♦ Power saving (reduction in power bills).

♦ Depreciation as per Income Tax Act in India.

♦ Uniform quality of end products.

♦ Better efficiency in plant.

♦ Reduction in MDI.

Applications of Automatic Voltage Controllers

Though, Servo Stabilizers are useful for any kind of applications, these are most suitable for 24 hour continuous process plants where breakdowns due to fluctuations results in heavy financial losses. Voltage Controller (Servo Stabilizer) can be installed either for the entire factory load or for selected feeders.

Technical Specifications of Servo Voltage Stabilizer

Servo stabilizers are available in a wide range and various models. The standard three phase models are suitable for balanced & unbalanced supply and loads. The standard models confirm to the following Specifications:

Input Voltage Range 360-450V 350-460V 340-460V 340-480V 320-480V 300-500V
Efficiency (as per calculation) 99.5% 99.3% 99.10% 99% 98.7% 98.10%
Output Voltage
Output Voltage Adjustment
Output Voltage Regulation
Correction Rate
Temperature Rise (Max.)
Mode of Systems
Wave form Distortion
Duty Cycle
400V ± 1%, 3Phase, 50Hz .
± 5%.
± 1% (at no load / full load).
10V -15V / second or as per requirement .
35°C-40°C above ambient.
Naturally Oil Cooled.
Class 'A'.
Fully Automatic / Semi Automatic / Manual.
On Uni-directional wheel.
100% Continuous.

Basic Power Circuit of Servo Stabilizer

*All specifications/calculations are subjected to change due to regular improvements in products without prior notice.

Description of POWER Make Automatic Voltage Controller

Servo Stabilizer primarily consists of the following

  • Linear, Plus / Minus type vertical rolling contact voltage regulator

    In our regulator we use heavy section of electrolytic grade rectangular copper strip instead of copper wire to minimize the losses & increase the efficiency of equipment. We are also using self lubricating Carbon Roller Assemblies instead of ordinary Carbon Brushes which offers more reliability and trouble free performance of the equipment.

  • Double wound Buck / Boost type series Transformer

    In our Buck / Boost transformer we use CRGO lamination to minimize iron losses and coils of Buck / Boost transformer are wound with heavy section of multi strips electrolytic copper to minimize copper losses for getting better efficiency of the equipment.

  • Electronic control circuit and meter panel

    Automatic Voltage Controller consists of very simple electronic control circuit for monitoring and controlling voltage, repair & maintenance of which is very easy ( ALTHOUGH IT IS NOT REQUIRED EVEN FOR SEVERAL YEARS ). The regulator and Buck / Boost transformer are oil cooled, housed in same or separate sheet steel tanks. Radiators are provided for effective cooling. The coils of voltage regulator & Buck / Boost Transformers are vacuum impregnated and oven dried as per IS.

Salient Features of POWER Automatic Voltage Controllers

Vertical Voltage Regulator

Carbon Roller Assembly

1. Onload Voltage Regulator

POWER Automatic Voltage Controllers are equipped with Vertical, Copper Strip Wound, Rolling Contact type Voltage Regulator. These voltage regulators are type, wound with heavy section of electrolytic grade rectangular copper strip and fitted with Carbon Rollers. POWER Voltage Regulators have higher efficiency of above 99% and are suitable for continuous duty cycle. Self lubricating Carbon Roller Assemblies offer more reliability and trouble free performance of the equipment. In POWER Voltage regulators Carbon Rollers move on both sides of the coil to give 440V or 230Volts.

2. Efficiency

The efficiency of POWER make stabilizer is more than 98-99.5% depending upon the input voltage range.

3. Better Llife

The life of POWER make stabilizer is more than 20 TO 25 years at full load.

4. Duty Cycle

POWER MAKE stabilizers are Heavy Duty, Industrial type, suitable for 100% load and continuous duty cycle. For running load of 200 KVA, POWER make 200 / 225 KVA is suitable.

5. Double Wound Transformer

Double Wound Transformer is a conventionally designed step down transformer and confirming to IS 2026 as regards the temperature rise and insulations are concerned. These transformers are wound with multiple strips of electrolytic prime grade copper strip to minimize power losses. Automatic Voltage Controllers are designed liberally as per capacity and are ideally suitable for marginal overloading conditions. Cooling ducts are provided to keep the hot spot temperature as low as possible. Coils are dried in electric oven and rigid connection support and coil clamping are provided to ensure high short circuit strength. We use very high quality 0.27mm to 0.3mm thick CRGO core, so no load losses becomes very less in our Automatic Voltage Controllers.

6. Windings

Coils are wound with paper covered electrolytic grade copper strip or synthetic enameled copper conductors. Cooling ducts are provided to keep the hot spot temperature as low as possible. Coils are dried in electric ovens. Rigid connection support and coil clamping is provided to ensure high short circuit strength.

7. Insulation

Precompressed board, PARMALI board and JAPANEESE insulation paper of best quality is used.

8. Core

The core is constructed from low loss, cold rolled, grain oriented, annealed laminations of electrical sheet steel conforming to the latest international standards. Special frame is built in-house for clamping the core to reduce the magnetic noise as well as making the whole structure rigid and robust.

9. Metering

Good quality of Voltmeter and Ammeter with selecter switches are provided on a separate panel to indicate the output voltage and current.

10. Temperature Rise

Automatic Voltage Controllers are designed for max. 40-45 degree temperature rise at top of oil whereas allowed limit is 50°C.

11. Oil

Oil tested for resistivity, dielectric and acidic characteristic conforming to IS 335. ABSOLUTELY NEW TRF. OIL IS USED BY POWER.

12. Tanks and Paint

The tanks are made of M.S. steel plated / sheets with adequate bracing & stiffeners. All the external surfaces are given a primary coat of Epoxy primer and finishing coat of Epoxy paint for better life.

13. Construction

Voltage Regulator and Buck / Boost Transformer are fitted in a common frame and housed in same sheet steel tanks. Absolutely new radiators are provided for better cooling. Servo Stabilizers are painted with EPOXY paint, which is resistant to acidic environment in the plant. We use new IS 335 grade Transformer Oil from Silvassa which provides better cooling and in turn increases life of Servo Voltage Stabilizer.

14. Payback Period

Owing to its high efficiency and associated benefits, the payback period for the cost of POWER's Automatic Voltage Controllers is from 6-12 months depending upon the input voltage variation and number of working hours of the plant. The HIGHER the input voltage the SHORTER will be the payback period.

15. Warrantee & Customer support

POWER's Automatic Voltage Controllers are warranted for 5 years against any manufacturing defect. Inorder to ensure complete customer satisfaction, we provide excellent customer service to our clients. We also offer friendly technical assistance for new installation where highly qualified engineers will attend your quiries.

Effect of Input voltage unbalancing

Servo Stabilizer for Unbalanced Input Voltage

Industrial units situated in residential / commercial areas and are not having their own distribution transformer, have the problem of unbalanced input voltage between phase to phase and many have the problem of frequent failure of three phase motors. Normally unbalanced input voltage problem persist for few hours a day and will have the following effects on the three phase motors.

  • With 5% Unbalanced Input Voltage between phase to phase - the LOAD will be unbalanced and the capacity of the motor reduces by 40%.

  • Consumption of the three phase motor will increase by 20 - 25%.

To avoid frequent tripping of the overload relays and to continue production, setting of motor relay is kept higher than actual required. The motors (particularly smaller motors up to 7.5 H.P.) can't withstand this high current for long time and in most cases the motor burns out and this high current flows through the relays, contactors, cables etc. resulting in failure of the same and in some of the cases may cause fire also.

The best option for such units having unbalanced input voltage, is to install Servo Voltage Stabilizer with Individual phase Control.

« Comparison between POWER make and dimmer type Servo Stabilizers

POWER Voltage Controllers

Servo Stabilizer using Dimmer

  • Linear, plus / minus, vertical type rolling contact Voltage Regulator is used.
  • Toroidal wire wound carbon brush type Voltage Regulator is used.
  • POWER Voltage Regulators are wound with heavy section of copper stip (having four times more cross sectional area) to keep lowest current density and thus above 99% efficiency is obtained.
  • conventional manufactures use wire wound voltage regulator popularly known as Dimmer or Varic. Due to lesser cross-sectional area current density is more, hence losses also. Efficiency of conventional stabilizer is 95%.
  • Due to lesser losses and compact design, oil quantity required become almost half.
  • More oil quantity is required to maintain the temperature within the limit.
  • To avoid wear and tear, self lubricating carbon roller assembly is used instead of ordinary carbon brushes. Hence the carbon deposit in the track is Nil, which offers more reliability and trouble free perfomance of the equipment. Life of carbon roller is about 1,00,000 Meter track level.
  • Carbon brushes slide over the windings and tends to wear off; there by causing carbon deposit in between turns, which naturally shortens the life of the regulator. Frequent track cleaning and replacement of carbon brush is required.
  • POWER stabilizers are of heavy duty type and suitable for 100% loading condition and continuous duty cycle.
  • Conventional Stabilizers can be loaded only up to 70% continuously.
  • Life of POWER Automatic Voltage Controller is 15 to 20 years full load.
  • Maximum life is 3 to 4 years at full load.
  • In POWER Voltage Regulator, carbon rollers are sliding in both sides of the coil. At full buck or boost condition,rollers will be in extreme end. In this position primaries of buck-boost transformer get direct supply from top rollers and bottom rollers help to form star connection. Regulator copper losses become zero and get approx. 99.5% efficiency.
  • In conventional regulator, carbon brush is sliding only in one side of the coil. At full buck or boost condition, current flow through the regulator winding become maximum and efficiency lowered to less than 94%.
  • Vertical regulator design in POWER Voltage Controller saves floor area.
  • Space required is almost double.
  • POWER Automatic Voltage Controller or Servo Voltage Stabilizers are warranted for five years in india. No risk for 5 years and no AMC is required.
  • Conventional Stabilizer suppliers normally offer one year warrantee. Later, end up in bearing risk for another 4 Years. In order to avoid the risk, customer is being compelled to go for expensive AMC for the rest of the years.

    Superior Features of POWER Automatic Voltage Controllers

    Comparison of Power Make Voltage Controllers with Conventional makes

    In the conventional dimmerstat of 100 Amps, winding is done using 10mm2 Copper wire. In our voltage regulator of 100 Amps, we use copper strip of 20mm2. That means cross sectional area used in our regulator is double than that used in dimmerstat by other manufacturers.

    In the voltage regulators manufactured by us, the roller moves on both sides of the coils. In one direction, it increases the voltage and in the other direction it decreases the voltage. In conventional dimmerstat, carbon brush moves only in one direction, requiring double capacity regulator used by us.

    Power losses of electrical equipments are directly proportional to the square of the current drawn by it. Considering the lesser cross sectional area and the need of double capacity regulator, losses of dimmerstat becomes four times compared to losses in our regulators. Because of this fact, efficiency of our voltage stabilizer is approx. 99% compared to less than 95% of conventional makes.

    This 4% better efficiency can save substantial amount of power in stabilizer losses as explained below:-

    In case of a 100KVA Voltage Stabilizer, four units of power per hour can be saved and the annual saving can be calculated as follows:-

    4units x 24 hours a day x 365 days x Rs. 4/unit = Rs. 1,40,160/-

    Carbon rollers instead of carbon brushes for lesser maintenance and long life

    In dimmerstat, carbon brush slide over the winding and tends to wear off, thereby causing deposition of carbon in between turns, which naturally shortens the life of the stabilizer. We use graphite carbon rollers instead of ordinary carbon brushes. Carbon rollers have negligible wear and tear and the carbon deposit on the track is minimum.

    Negligible losses at full buck / boost conditions

    In dimmerstat, carbon brush slide over the winding and tends to wear off, thereby causing deposition of carbon in between turns, which naturally shortens the life of the stabilizer. We use graphite carbon rollers instead of ordinary carbon brushes. Carbon rollers have negligible wear and tear and the carbon deposit on the track is minimum.

    100% duty cycle reduces KVA requirement.

    POWER make Automatic Voltage Controllers are heavy duty type designed for 100% continuous duty cycle. Conventional voltage stabilizers are equipped with dimmerstat / variac and suitable for 60-70% duty cycle. So we have to consider 400 KVA conventional type stabilizer instead of a 250KVA POWER make voltage stabilizer.

    Long life at full load

    Life of POWER make voltage controllers is 20 25 years against to 5 6 years in case of conventional voltage stabilizers.

    5 Years Warrantee

    POWER Make voltage controllers are warranted for 5 years in India. During this period we do not charge anything for spares or services. Conventional voltage stabilizer manufacturers normally offer one year warrantee. Customer will be compelled to go for expensive AMC for the rest of the years.

    Also, stabilizers are categorized under ENERGY SAVING EQUIPMENTS. The stabilizer should be such that its own consumption is minimum otherwise the basic concept of Energy conservation will be lost. Therefore while deciding for a stabilizer it becomes necessary to invest the capital over a period of time to ensure that its running cost is minimum and payback period is quickest. From the above facts, you will find that our stabilizers will cost much lesser in long run to conventional type stabilizers.


    « Electroplating purposes
    « Aluminium Anodizing
    « Chemical Processes
    « Electro Coagulations
    Ultra Super isolation Transformers are effective for isolating sensitive equipments from Live Voltage transients, Spikes and DC leakage etc. They are specially designed for sensitive critical equipments like Medical Instrumentation, CNC Machines etc.
    Capacity 30KVA to 8000KVA
    Designed and Managed by Team TRANS POWER SYSTEMS © 2013 Trans Power Systems