RANGE: Upto 7000 kVA For Low Voltage Class


In spite 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 upto 7.5 H.P.) in three ways:

1. Higher current produces higher losses in electrical motors which causes premature failure of winding.
2. These higher losses of electric motors also increase the losses of cables, switches, transformers & other associated equipments.
3. For smooth continuous operation of motors, over load relays are usually set at 20% higher setting.


With the installation of the Servo Controlled Voltage Stabilizer and maintaining 390/400 volts, the motor will operate smoothly drawing 15 - 20% lesser current

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

Input Voltage




400 7.5 A 5.2 0.8
425 11% More 18% More 0.7
435 19% More 28% More 0.61
445 26% More 38% More 0.57
The table below compares the behavior of 60 watt lamp at different voltage:




Luminous Intensity

Life in Hours

220 0.25 54 W 690 2000


0.26 60 W 710 1000
240 0.27 65 W - 8.3% More 820 575
250 0.28 70.6 - 17.6% More 943 338
260 0.29 75.4 - 25.6% More 1073 200
270 0.31 83.4 - 39% More 1213 100

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 motor 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.

Loss Comparison of Muskaan Make Regulator & Conventional make Regulator


Muskaan make Roller type 
regulator losses

Conventional make Carbon brush type Dimmerstat losses

60 A

575 W

1050 W

75 A

730 W

2055 W

100 A

900 W

3105 W

Table below gives approximate quantitative advantages of automatic voltage controller at various fluctuation levels:

Input Voltage

% Reduction in Breakdown Possible

Motor Load 
Below 10 HP.


Approx. Power Saving Possible

Motor Load 
Below 10 HP.


380-400 volts




Nil & Servo
Stabilizer Required

380-420 volts





380-440 volts





360-460 volts





360-480 volts





340-500 volts






Description of Servo Controlled AVC:
MUSKAAN’S Servo Stabilizer is manufactured as per IS : 9815 and primarily consists of the following:

1. Liner Plus / Minus Type Vertical Rolling Contact Voltage Regulator

In our regulator we are using 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. 

2Double Wound Buck / Boost Type Series Transformers
In our Buck / Boost transformer we are using 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.

3. Electronic Control Circuit and Meter Panel
MUSKAAN Automatic Voltage Controller consists of very simple electronic control circuit for monitoring and controlling voltage, repair & maintenance of which is very easy.

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.

Superior Features Of Muskaan's Make AVC.

Temperature Rise

It is designed for 30-35 degree C above ambient. Suitable for any kind of ambient temperature conditions. 

Core is constructed from Low Loss of CRGO M-4 Grade confirming to latest standards & is fitted & clamped with special built in-house frames to reduce the magnetic noise & to make the structure rigid & robust.

Use paper covered electrolytic grade copper strip for winding. Cooling ducts are provided to keep the hot spot temperature as low as possible.

Tanks & Paint
Tanks are made of M.S. Sheets with adequate bracing & stiffeners are given a coat of Epoxy Primer & Epoxy paint for better life. Both light grey & Siemens grey (RAL 7032) are available in colour.

Oil of IS: 335 standard is being used & is filtered before topping. 




Technical Specifications
MUSKAAN’S Servo Stabilizer are available in wide range & various models according to customers requirement for Balanced / Unbalanced supplies with following specifications:

Input Voltage

360-460 V

360-460 V

320-480 V

300-480 V

280-500 V

Efficiency (Approx.)


99.3% 99% 98.8% 98.7%

Output Voltage

400 V Â± 1% 3Phase, 50 Hz*

    . .


Naturally Oil Cooled

    . .


Indoor / Outdoor

Response Time: Instantaneous   .

Temperature Rise ( Max.)

30C above ambient

Accuracy: ± 1% . .


On Uni-directional Wheels

. . . .

Wave form distortion


. . . .

Duty Cycle

100% Continuous

. . . .
*Non standard ranges are also in our scope of supply. Output voltage of 380 - 415 volts is also in scope of supply.

Comparison Between Muskaan's make & Conventional make Automatic Voltage Controller

Muskaan's make roller type regulator

Conventional make with carbon brush regulator

  • Power consumption is 0.5 to 1.5% depending upon the model and input voltage variation
  • Suitable for continuous 100% duty cycle
  • The carbon (graphite) Roller rolls, while moving on the coil track, so contact Point of the roller goes on changing which prolongs the life of the rollers
  • Life at full load is 15-20 years
  • Negligible losses in full Buck / Boost Condition
  • Five years Unconditional Guarantee
  • Power consumption is 2 to 7% depending upon the 
    model and input voltage variation
  • Suitable for only 50% to 60% duty cycle
  • Since the contact is by brush having flat surface, wear & tear of the brush is more and requires frequent replacement
  • Maximum life is 3-5 years at full load
  • Max. Losses in full Buck/Boost condition
  • Normal Guarantee/Warantee for one year

  • Power Saving ( Reduction in Power Bills )
  • Reduction in breakdown of electrical / electronic equipments
  • Reduction in MDI
  • Improvement in Power Factor (At Higher Voltage)
  • Uniform Quality / Lesser Tripping
  • Improvement in quality of end products
  • Better Efficiency in Plant
  • Unmeasurable Benefits
  • Depreciation as per income tax act (In India Only)
Payback Period
It has been assesed with long experience & customer’s feedback that the payback period of Automatic Voltage Controller is well within 6-12 months depending upon the site conditions.