Messung Electrical Engineering



At the outset, let’s understand that every machine, appliance, industry, plant, mall, commercial complex, hospital, school, etc. has its own input and output voltage requirements. Moreover, they all need a steady, optimised supply of voltage to ensure performance and life of machinery.

Electrical current supplied directly from the power/hydroelectric stations/ step down transformers often have huge loads, and can fluctuate rapidly. If such fluctuating current is fed to a machine or an appliance, it may cause an overload or create short circuit rendering the appliance useless for further use.

A servo stabilizer is a servo motor-controlled stabilization system that delivers optimum voltage supply using a buck/boost transformer booster that captures voltage fluctuations from input and regulates current to the correct output. An AC synchronous motor adjusts voltage in clockwise or anticlockwise direction and manages the output voltage with components like control card, dimmer, comparator, transistors, mocs, etc.


Ever wondered about stabilizer working?

  1. Voltage received from the mains is continuously sensed by accessories circuitry. Whenever there is a high or low voltage at the input, the Microprocessor gives a trigger to the motor driver.
  2. Based on the information, the motor driver moves the servo motor across the winding of the autotransformer to increase/decrease the number of winding.
  3. Hence, the voltage across the primary of the buck-boost transformer increases or decreases since autotransformers output is connected to the primary of buck-boost transfer.
  4. The process takes place continuously to correct input voltages and deliver stable voltage at the output.
  5. In case of a 3 phase servo regulator, each phase has its back/boost transformer and dimmer to correct each phase independently.

Servo stabilizer circuit diagram

3 phase servo controlled voltage stabilizer circuit diagram

3 phase servo controlled voltage stabilizer circuit diagram


Relay stabilizers are built with electromechanical relays to provide output voltage within a desired range. Whenever the voltage rises or falls, the control circuit switches the corresponding relay to connect a desired tapping to the output voltage. Relay stabilizers usually deliver output voltage accuracy of +/- 10%. It is used for low rating appliances in homes, offices and industries.

In servo stabilizers, a phase of buck/boost transformer primary is connected to the fixed tap of the auto transformer and another connects with the moving arm which is controlled by the servo motor. Servo stabilizers provide output voltage +/- 1 % input voltage change up to +/- 50%. These stabilizers provide higher correction speed, high precision of stabilized output, capability to withstand inrush currents, and above all, high reliability.


Almost every industry today has invested in servo stabilizers to protect their processes, ensure continuity of critical operations, and enhance life and performance of electrical equipment. Use of stabilizer is a given in modern industry. Let’s check out some of the industry applications of servo stabilizers.

CNC machines
CNC machines are calibrated for utmost precision and are a part of time-based manufacturing processes. Moreover, they involve delicate circuitry that can get damaged due to voltage fluctuations. Investing in a servo stabilizer can be the best way to prevent to electrical damage to CNC machines and ensure long life.

Packaging industry
The packaging industry used big automated machineries, conveyor belts, robotic and other systems. If a single component slows down or halts, the entire production line is affected. Voltage fluctuations can cause such breakdowns so using a servo stabilizer can keep the line running smoothly and cut downtime.

Textile industry often use three-phase supply line which experience voltage fluctuations on a regular basis. Textile machines are usually high-speed machines programmed for accurate, repetitive tasks. A servo stabilizer can arrest these fluctuations so that the machines function without any technical issues like overloading.

Hospitals/Medical equipment
Medical equipment and other sensitive machines in hospitals and diagnostics have little tolerance for voltage problems. Servo stabilizers are therefore crucial to prevent overloading of critical machinery such as CT scanners, MRI machines, life-saving respirators and more.

Printing Machines
Servo stabilizers are a must-have device for printing industry and for machines such as flexographic machines, Offset lithography, Flexography, Digital printing inkjet & xerography etc. The slightest change in voltage variation may create havoc of printed material.

Plants / Factories
Industrialist have understood the importance of servo voltage stabilizers and voltage controllers for smooth operations. Hence, they make a provision for servo voltage stabilizer in their budget. These voltage regulators not only help them in achieving good power factor, they also provide benefits like negligible failures of costly machineries, tools, reduction in MDI, power savings, reduced downtime, etc.

Cold Storage Plants
Cold storage plants play an important role in storing food material before distribution to markets. The machines installed work 24×7 and need to maintain the temperature and quality of the food stored in it. So continuous functioning is imperative. If voltage is higher or lower than required or if there is huge fluctuation of input voltage, it could lead to reduction in efficiencies, power loss, equipment malfunction, power factor penalties, equipment overheating, early failures, increased maintenance and more. Servo stabilizers are therefore a necessity in cold storage plants.

Both commercial and residential elevators face problems with power control. Due to irregular flux like over/under voltage, these lift motors are more prone to damage. They can sometimes overheat or weaken their magnetic current rotation. As a result, it might lose a phase and stop working.

Servo voltage stabilizers ensure just the right output of electricity to keep elevators running safely and smoothly.


Messung Electrical Engineering Division is Master Distributor for Fuji Electric Consul Neowatt, the No 1 Servo Controlled Voltage Stabilizer (SCVS) brand in India. Fuji’s reputed range of air cooled and oil cooled industrial servo voltage stabilizers for both balanced and unbalanced loads in a range from 3 to 3500 KVA.

Fuji offers models for both indoor and outdoor applications and also provides customized products based on application requirements. They also offer a full range of isolation, ultra-isolation and K-rated transformers for various applications in a range from 3 – 1000 KVA.

Trust Fuji’s servo-controlled voltage stabilizers for your CNC Machines, CMM, Textile & Spinning mills, Cold Storage units, Food processing equipment, CT Scanners, MRI machines, Retail outlets, Restaurants and Office applications. Contact Messung today.