PWM-IGBT Based Static Stabilizer
Launched upto 100 KVA
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Approved supplier
to Ministry of Defense
& Urban Development,
Government of
Sri Lanka

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Static Stabilizer (PWM-IGBT)

The static stabilizer offers a reasonable improvement on slow servo controlled stabilizer as well as other static tap changing stabilizers. This technology does not cause di/dt problems as it does not switch the power path. The basic topology is with buck-boost transformer with high primary to secondary ratio for voltage correction of ± 25%. The control voltage is imposed on the primary of this buck-boost transformer. The voltage regulation with help of buck and boost topology is achieved electronically without the step changes in voltage that occur when the system regulates. This task is accomplished through a feedback and a control system implemented by using a microcontroller.

The system uses IGBTs as power switches. Direct AC-AC converter circuit improve the overall system response and fast voltage correction. No storage capacitor increase life of the system. 20Khz PWM control operation using high end dsPIC controller to achieve correction time of 1 to 1.5 cycle. Excellent performance in voltage sensitive application.

  • What is Requirement of voltage regulator?
    We don’t have any control over Input voltage source or transient/fluctuation generated by other load connected on the same grid. Electronics equipment are not designed for the wide input voltage range and in case of beyond specified input under and over voltage causes

    • Permanent Damage to the load
    • De-rate the life of load
    • Unwanted interrupt in load operation

  • What are limitations of available voltage regulators?
    Since Long, conventional methods like Servo voltage stabilizer and Tap Changer AVR are used In industrial, commercial and residential application.But, these technology has following limitations,

    • Very slow correction speed
    • Slow Correction time
    • Interrupts power path at the time of regulation (tap changing method)
    • Mechanical component limitation or failure
    • Manual Bypass
    • Low reliability
    • Low regulation

  • Principle
    • Delta Voltage is added and subtracted at the primary of buck-boost transformer by IGBT based AC – AC converter to regulate output voltage

  • What is Static Voltage Regulator?
    • Major conventional voltage regulators are working on motor moving part or mechanical tap changing relay principle
    • Static Voltage Regulator is working on IGBT based PWM Control technique
    • At the primary of buck-boost transformer delta Voltage is added and subtracted by IGBT based AC – AC converter to regulate output voltage
    • Rating of the AC-AC convert is ¼ (as per input voltage range) of the rated power

  • What are the advantages of Static Voltage Regulator?
    • Compact in the size compare to conventional regulator
    • Very fast correction speed of 20Khz
    • Very fast correction time of 20-30ms as compare to conventional regulator (200 – 5000ms)
    • Excellent voltage regulation of +/- 1%
    • Auto bypass
    • No moving parts so no wear and tear and high reliability No maintenance
    • Silent operation
    • Excellent load protection capabilities to ensure load life

  • Output Short Circuit Protection

    • Detects abnormally heavy currents flow from input and indicate occurrence of short circuit. Instantaneous tripping will isolate the load and at the same time turn off IGBT converter thereby provide protection against further damage.

  • Key comparison of Static voltage Regulator and conventional regulators
    Technology specifications Static Voltage Regulator Servo voltage Regulator Tap changing voltage Regulator
    Correction speed Fast Very Slow Slow
    Correction time 20-30ms 50ms-5Sec 200ms-1Sec
    Auto bypass Yes No No
    Stability 1% 2% 2%
    Reliability Excellent Good Fair
    Load protection capabilities Excellent    
    Interrupts power path at the time of regulation No No Yes
    Power cycling transient No Yes Yes
    Size Very Compact Compact Compact
    Maintenance No Yes Yes (In case of Relay)

    PWM Controlled Static Voltage Stabilizer V/s Tapchanging or Servo Mechanical Stabilizer
    PWM Controlled IGBT based technology Other Conventional Electromechanical Stabilizer
    Designed with fully solid state components to govern regulation, no moving part or tapchanging mechanism (relay / static device) This conventional method is designed with moving part (motor) or tap changing mechanism (Relay / static device) to govern regulation
    No maintenance required Periodic preventive maintenance required
    Due to the fully solid state drive and power circuitry which uses no mechanical parts in the regulation circuitry, operation is highly reliable, precise, noiseless, interruption-free and fast and the units are absolutely free from wear and malfunctions. The motor driven mechanical system, motor commutators, and the moving brushes on the variable transformer need
    Exceptionally high speed of voltage correction to meet modern voltage sensitive equipment Slow speed of voltage correction to meet modern equipment
    Because the series of Static Automatic Voltage Stabilizers function only through static electronic components, the speed of the line and load regulation is exceptionally high (of the order of 360 v/sec. line and 500 v/sec. load regulation) Ideal for modern voltage sensitive equipment. Because of the inertia of electro-mechanical regulation gear, Motor Driven Voltage Stabilizers can only respond to regulate the voltage fluctuations at a speed of 40 v/sec. in general and 70 v/sec. maximum.
    Inbuilt auto-bypass with no transition time In conventional stabilizer auto bypass is not there or with limitations
    PWM controlled IGBT based technology has advantage of providing auto bypass. System will get bypass if any electronics part will get failed with no transition time. In conventional method to achieve auto bypass feature excessive switch gear is required which add cost to the system as well this solution will provide power interrupt during bypass
    Same correction speed in all power range Correction range vary according to power range
    Static Voltage Stabilizer are manufactured through the power range from 2 KVA single phase to 600 KVA tri-phase with the same design and operation principal. Only different driver PCB's (printed circuit boards) are used all through the standard power range, so the compactness and reliability is unchanged. The Motor-Driven Voltage Stabilizers require excessive switch gear and additional buck-boost transformers when the nominal power is increased above a certain level.

  • Performance of PWM-IGBT based Static Voltage Stabilizer vis-a-vis Servo Voltage Stabilizer
  • Comparison between Suvik Static Stabilizer and Other Static Stabilizers
    Sr. No Parameters Suvik
    Static Stabilizer
    Static Stabilizers
    1 Regulation +-1% +/-3%
    2 Standard input range 170-290VAC 175-280VAC
    3 Over Load Protection Yes* No
    (Only MCB at input)
    4 Output and input over voltage under voltage protection Yes No
    5 Contactor at output Yes No
    6 LED & LCD for Metering and parameter and fault display Yes No
    7 Single phase prevention in case of phase loss (Three Phase system) Yes No
    8 Output Short Circuit Protection
    Yes No
    * Over load protection at different load level, >150% 1minute, 300% immediate
Three Phase User Manual
Single Phase User Manual


  • Single phase
  • Three phase
3 KVA to 30 KVA
10 KVA to 100 KVA
* Above 100 KVA models are available on request

Input Voltage Range

  • Standard
  • Standard
170-290 volts ac, 1-phase, 2 wire, 50Hz
340-480 volts ac, 3-phase, 4 wire, 50Hz
Regulator Technology : High frequency 20k Hz IGBT driven voltage regulation converter.
Pulse width modulated (PWM) controlled direct ac to ac converter topology.
Input Nominal Voltage : 230 volts ac, 1-phase, 2 wire, 50Hz
400 volts ac,  3-phase, 4 wire, 50Hz
Input Nominal operating voltage : Range: 170-290 volts ac, 1-phase, 2 wire, 50 Hz
Range : 340-480 volts ac, 3-phase, 4 wire, 50Hz
Input Nominal Frequency : 45 to 65 Hz
I/P circuit breaker & over current protection : I/P circuit breaker (with limited inrush current capability) & over-under voltage cut-off (at greater than 300 vac or less than 160 vac)
Output Nominal Voltage : 230/400 volts ac, three phase wye
Efficiency : Better than 96% (with 20-100 % load conditions)
Output Voltage Regulation : Nominal ± 1 % maximum under 0 to 100 % load & input of 185~265 vac
Automatic Bypass : Automatic bypass will be activated when there is a fault condition.
Safe Start : Unit starts on sine wave zero voltage crossing point upon turn-on.
Unit is fully functional/regulated within 5 seconds of mains restoration.
Common mode filtering : Neutral-ground bond eliminates all noise or voltage on neutral (< 0.5V) (in case of inbuilt IT)
Normal mode filtering : A built-in inductor-capacitor filter attenuates EMI/RFI noise from O/P.
System Status Indicator : Green LED (ON) indicates Normal (regulating mode) operation, Green LED blink - I/P or O/P UV/OV, Red LED-tRIP, Red LED blink - Overload short circuit.
Surge Let-Through
(in case of inbuilt IT
or on request)
: Category A3, Ring Wave, 200 A: L-N:30 V. L-G : 30 V
Category B3, Combination Wave, 3000 A : L-N : 200 V, L-G : 200 V
Safety Standards : Protection class IP20.
Ambient Temperature : -5° to +50°C . 10 to 90 %.  RH non-condensing
# For more detailed specification refer catalogue
  • Regulation speed 500V / sec
  • Handles crest factor of 5:1
  • 20ms response time
  • A soft start feature
  • Output Short Circuit Protection
  • Manual by-pass facility
  • Built in isolation Transformer
  • Out-door versions
  • Reverse polarity protection
  • Noise and interference dv/dt filter
  • EMI/RFI noise filter
  • LCD for parameter and fault display
  • IT layout
  • Cabinet Design
  • Colour Shade
  • Cable entry
  • Termination box
  • Terminals for
Optional as per requirement
Indoor with IP protection
Out door