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Rectifier Transformers

Salient Features
Brief Specifications
Starting Circuitry
Circuits & Components
Advantages over Thyristorized
Why Regulator Rectifier?
Comparison with Dimmer type


POWER is a name known for reliability and continuous improvement in the field of Rectifier Transformers using vertical, copper strip wound, rolling contact type voltage regulators. We are also manufacturing Industrial Servo Voltage Stabilizers, Automatic Voltage Controllers, Servo Stabilizers, Anodizing Rectifiers, Electro Colouring Transformers, Electro Plating Rectifiers, Distribution Transformers, Isolation Transformers, Variable DC or AC Power Supplies and Voltage regulators.

Rectifier transformer is an equipment that converts AC into DC supply. Power make Silicon Rectifiers are widely used in Electroplating, Anodizing, Hydrogenation and all other electrochemical processes. These are tailor made, covering a wide range from 200 Amps to 30000 Amps at different output DC voltages as per requirement.

Salient Features of POWER Rectifier Transformers

♦ Energy Efficient Technology.

♦ Power Factor - Above 0.95.

♦ Field Proven Technology.

♦ Compact Design for Space Saving.

♦ Designed for 100% Continuous Duty Cycle.

♦ Negligible Maintenance.

♦ Tested at each & every stage of manufacturing.

♦ Liberal design and rigorous testing.

♦ Five years warranty in India.

Brief Specifications

Input Voltage

380- 440 Volts, 3-Phase 50Hz. AC supply or any other voltage.

Output Voltage

DC variable from zero to maximum rated voltage.

Output Current

Rated maximum DC current.

Temperature Rise

Less than 45°C above ambient at the top of the oil.


Depends on voltage current rating of rectifier.

Ripple Content

Less than 5%.


‘A’ class for oil cooled.

Starting Circuitry - POWER Rectifier Transformers

Inner view of Rectifier

AC Input

POWER Rectifier Transformers are designed for three phase, 50Hz AC input supply and are suitable for operation at any voltage between 380-440 Volts in India and can be designed for 60Hz AC and any other voltage available. Input to the Rectifier Transformer should be connected through a proper protective device, to provide positive protection to personnel and the system which is not included in our scope of supply and has to be procured separately.

DC Output

The DC output is continuously and steplessly variable from zero to the full rated voltage for any input voltage between 380-440 Volts and for any load between zero to its rated full load. The ripple content in the output is less than 5% and these units are very much suitable for all special processes such as Chrome Plating or Hard Chrome Plating where low ripple content is necessary.

Circuits & Components - POWER Rectifier Transformers

Vertical Voltage Regulator

Carbon Roller Assembly

The circuit employed in POWER Rectifier Transformers is simple. Input 3Phase 415V supply is given to Vertical, Copper Strip Wound, Rolling Contact type Voltage Regulator, which in turn supplies a variable voltage to the primaries of a three phase, double wound, Delta / Double star connected transformer. The secondary of the transformer is connected to Hexa-Phase connected rectifier using Silicon Diodes. The output is obtained from the Rectifier and the star points of the transformer through an Interphase Transformer. Moving Coil Voltmeter and Ammeter with shunt are provided to measure the output voltage and output current.

1. Onload Voltage Regulator

POWER Rectifier Transformers 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 approximately 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. We design Rectifier Transformers in “Q” connection in which the regulator current is half the line current so losses are less and life is much more.

2. 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. RectifierTransformers are designed liberally as per capacity and are ideally suitable for marginal overloading conditions. Combination of double primary winding in transformer and double output from voltage regulator help us to form “Q” connection in which the regulator current is half the line current so losses are less and life is much more. Cooling ducts are provided to keep the hotspot 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 Rectifier Transformers.

3. Interphase Transformer

Connected between the two star points of the secondary of the step down transformer. It increases the rating of the diodes.

4. Silicon Diodes

Diodes are arranged in Six Phase Circuit. We use absolutely new diodes in our Rectifiers. Diodes are tested in house and similar PIV batch diodes are used in one equipment for equal load sharing and reducing the power loss of diodes. We use diodes up to 50% more in capacity for better durability.

Silicon Diode


5. Metering

Good quality of Voltmeter and Ammeter are provided on a separate panel to indicate the DC output voltage and current. Ammeter is used in conjunction with shunt fitted inside the tank.

6. Control

We use Motorized on load voltage regulator in our Rectifier Transformers. Output Voltage / Current can be varied by pressing Raise / Lower switch fitted in Control Panel. We also provide ‘T Handle’ which can be used in case of failure of Motor circuit.

7. Construction

Voltage Regulator, Transformer, Diodes etc. are fitted in a common frame and housed in same or separate sheet steel tanks. Absolutely new radiators are provided for better cooling. Rectifier Transformer is painted with EPOXY paint, which is resistant to acidic environment in electroplating plant. We use new IS 335 grade Transformer Oil from Silvassa which provides better cooling and in turn increases life of Rectifier Transformers.

8. Optional attachments

Constant voltage controller (CVC)

We offer CVC electronic attachment with Rectifier transformer, which will maintain constant output voltage as per setting automatically, irrespective of input voltage or load variation.

Constant current controller (CCC)

We offer CCC electronic attachment with Rectifier transformer, which will maintain constant output current as per setting automatically, irrespective of input voltage variation.

9. Warrantee & Customer support

POWER's Rectifier Transformers 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.

Advantages as compared to thyristor controlled Rectifier Transformers

Rolling contact type

Thyristor controlled

No wave form distortion at any load. Wave form distortion in thyristorised type.
Electrical wave form is like a moving wheel. For 50% Rated Voltage the dia of wheel is reduced accordingly i.e, magnitude for a wave is decreased. It is like cutting the wheel by 50% and then moving the wheel i.e, wave form is cut as shown at full magnitude.
Higher power factor of more than 0.98 is achieved. The power factor is lower between 0.5 to 0.75.
The system is simple and can be repaired and maintained even by simple mechanic. The system is specialized and need specially trained Electronic Engineer to repair and maintain.
The cost of spares is very negligible. The cost of replacement is very high.
Over all losses are less. Over all losses are more.
Warranted for 5 Years. Normal warrantee is for 1 year.

Why the regulator control is superior to thyristorised control in rectifier?

  • In electroplating application the regulator is better and technology is adopted in Germany and Europe because as explained in advantages.

  • Other manufacturers of rectifiers have shifted to thyristor controlled, because they do not have the technology of rolling carbon roller regulators.

  • Manufacturers of Thyristorised Rectifier Transformers claim that their rectifier has less losses than regulator. They compare thyristor with sliding carbon brush type regulator. In our case their claim is not true. We use vertical, copper strip wound, rolling contact type Voltage Regulator. The copper section is three times, so the losses are almost 1/5 or 20%.

  • In our regulator the roller moves on both sides of the coil to give ± 440V or ± 254V output. We design the rectifier in 'Q' connection in which the regulator current is half the line current so losses are less and life is much more.

Comparison between POWER make and dimmer type Electroplating Rectifiers

POWER Rectifier Transformers

Rectifier Transformers with 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.
  • conventional rectifier manufactures use Dimmer / Variac in which carbon brush is sliding only in one side. In this design, regulator current is equal to line current so losses are more hence life is less.
  • POWER make Rectifier ensures better efficiency due to lesser regulator losses.
  • Due to higher regulator losses, efficiency of dimmer type rectifier is poor.
  • In POWER regulator, roller moves on both sides of the coil to give +/-440V output. We design the rectifier on 'Q' connection in which the regulator current is half the line current, so losses are less and life is much more.
  • Conventional rectifier manufactures use Dimmer / Variac in which carbon brush is sliding only in one side. In this design, regulator current is equal to line current so losses are more hence life is less.
  • 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 Rectifires are of heavy duty type and suitable for 100% loading condition and continuous duty cycle.
  • Conventional Rectifiers can be loaded only up to 70% continuously.
  • POWER Rectifier equipments are warranted for five years in india.
  • Conventional Rectifier suppliers normally offer one year warrantee. Later, end up in bearing risk for another 4 Years.
  • Compact in built regulator design saves space.
  • Space required is almost double.

    Main technical features:
  • Input 400Volts 50HZ supply.
  • Rolling contact ( carbon roller) type copper strip wound regulator.
  • Sinusoidal AC waveform.
  • Stepless output voltage adjustment.
  • Adjustable process time.
  • Auto cut off.
  • Oil cooled construction for long life.
    Automatic Servo controlled Voltage Stabilizers are manufactured upto 8000KVA. Purpose of installing voltage stabilizer is to get constant voltage from a fluctuating AC input supply. It can be installed either for your entire factory load or for selected feeders.
    Capacity – 30KVA to 8000KVA
    Designed and Managed by Team TRANS POWER SYSTEMS © 2013 Trans Power Systems