Servo Controlled Automatic Voltage Regulators

In many supply systems considerable variation is encountered in the mains voltage for which it is designed. The hazards of over-voltage are well known and these voltage fluctuation constitute a serious problem for users of most of the electrical equipments. Considering the above facts, SERVO CONTROLLED AUTOMATIC VOLTAGE STABILIZERS are designed and manufactured by us for the healthy operation of sophisticated equipments of every industry and research institution,

(precision laboratory equipments, radio transmitters, radar devices, computers) general industrial production and process control equipments or even controlling the entire supply to a laboratory, testing room/factory, that too at a substantial saving in cost. PVJ POWER SERVO MOTOR CONTROLLED AUTOMATIC VOLTAGE STABILIZERS (Servo type Automatic Voltage Stabilizers) are based on the principle of feedback information, and are manufactured from the highest quality raw materials available.
These regulators are high speed electromechanical regulators and are manufactured using the latest technology so as to provide constant voltage for supplying the desired voltage without any harmonics and can even operate over a wide temperature range.

Applications of SERVO Voltage Stabilizer

CNC Machines Air Conditioning Plants
Telecommunication Networks Motor Loads
Data Processing Equipment Bio Medical Equipment
Drives, PLC’s Induction Heating
Hotels Defense Application
Industrial Units Lighting Loads
Residential/ Offices Farm Houses
R & D Institutions Sophisticated Laboratories

Key Features

  • High response, low inertia rugged A. C. servo motor.
  • Critically damped response on all loads/supply conditions.
  • Energy savings due to high efficiency and superior transformer design.
  • High quality raw materials used – prime grade CRGO lamination and high purity electrolytic copper wires/strips used.
  • No wave form distortion.
  • High speeds of correction up to 35V/sec for three phase and 20V/sec for single phase.
  • Machine wound Variacs with special carbon brushes for enhanced life.
  • Voltage adjustment on output.
  • Simple, systematic construction for dependability and ease of maintenance.
  • Solid state control circuitry.
  • Conforms to IS:9815 specification.

How to choose a Servo Stabilizer

There can be three types of loading conditions in an electrical system

  • All the loads are of three-phase nature.
  • There is a mixture of three-phase and single-phase loads.
  • All the loads are of single-phase nature.

In view of the above facts and the guiding principle, the choice of a three phase stabilizer for condition (a) and (b) falls on balanced load type stabilizer.

An unbalanced load type stabilizer should be used only for option
In spite of the selection of the type of 3- phase stabilizer, it is imperative to point out that the neutral needs to be solidly grounded for proper functioning of the electrical system.

Choosing the right KVA of a Servo Stabilizer Some thumb rule conversions factors for choosing the right KVA of the Servo Stabilizer.

  • KVA of Stabilizer = H.P. of lift * 3
  • KVA of Stabilizer = Tonnage of A.C. plant * 2
  • KVA of Stabilizer = H.P. for Resistive loads
  • KVA of Stabilizer = H.P. or K.W./ Power factor for Reactive loads.

The stabilizer KVA needs to ascertained and designed using the pack conditions.

Specifications Single Phase Three Phase
Input Volts* 160-260V 300-440/360-500
Output Volts* 230 +/- 1% 380/400/415 +/-1%
Efficiency >95% >97%
Frequency 48-52 Hz 48-52 Hz
Wave-Form Distortion Nil Nil
Temperature Depends on type of cooling and IS Specifications Nil
Environment Designed for indoor tropical use Nil


Auto/Manual Switch Low/High voltage trip
Voltmeter on Output Short Circuit Protection
Output Volts Adjust Single Phasing Protection
Lower/Raise in manual Input/Output Voltage Metering
Mains Indication Reverse Phase Protection
Voltmeter/Ammeter Isolation Transformer
Selector Switch (30 units) Temperature Gauge
Silica Gel breather

Why PVJ branded SERVO is Preferred

Servo Voltage Stablizer

1) Our special design SERVO uses a variable speed servo motor along with proportional type of control circuit, which ensures that the voltage fluctuations are corrected quickly without any oscillations at the output so as to protect the end equipment.

2) The rate of voltage correction is 2-3 times faster in our SERVOs as compared to competitive brands. Designed to work on Unbalanced Line & Load conditions wherein each phase is individually controlled with separate variable speed Motor & Electronic Controls.

3) The response time of stabilizer quick at 10 msec. The improved efficiency of 98% compared to typical 95% available in the market will reduce running costs. Substantial saving in the electric bill (lower power losses) will pay back the cost of equipment in 2/3 years.

4) They are D.G. Set compatible:
Special RMS sensing circuit ensures no drift in output voltage even with distorted waveform, generally observed in D.G. Set. This avoids nuisance trippings of advanced electronic equipment, otherwise observed.

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