Our home electric supply is Alternating Current (AC) whereas the most common electronic device that we use, the mobile runs on Direct Current (DC). So how does the mobile gets charged? This is where the rectifier comes into action.

It all started in the year 1885, when the first constant potential transformer was invented. Since then, transformers have become very essential for the distribution, utilization, and transmission of alternating current electric power. 

Transformers are most commonly used for decreasing high AC voltages at low current increasing low AC voltages at the high current for coupling the stages of signal-processing circuits and in electric power applications. Transformers are also used where the voltage in and out equals each other. It can also be used for isolation. 


There are various ranges in the size of transformers build by rectifier’s transformer manufacturers. The units sometimes range less than a cubic centimeter to weighing hundred tons.

What is a Transformer Rectifier?

A transformer rectifier is a type of transformer that has thyristors otherwise diodes inside the same tank which includes voltage regulations. Transformer rectifiers are mostly used for industrial purposes. This process is carried out by using a significant direct current supply. The rectifier used for industrial purposes is included of direct current traction, smelting, electrolysis, variable-speed drive trains, and etc. While applying the principles transformer rectifier’s manufacturers consider the following:- 

  1. For higher voltages thyristors use the connection like bridge-type.
  2. For applications interphase connection is used.
  3. Number of pulses i.e. 6, 12, and above with phase-shifting. 
  4. Harmonic issues and eddy current.


Voltage regulation can be very smoothly attained through the on-load tap or no-load changers on the high voltage region. With the help of the saturable reactors, fine levels of regulations can be obtained. The units of regulations can be fixed or else separate.

Transformer Rectifier Working Principle

A transformer rectifier unit (abbreviated as TRU) unites both the rectifier and transformer into a single unit. The main function of a transformer rectifier is to convert alternate current into direct current. This conversion of current is known as rectification. There are several different forms of transformer rectifiers. However, modern-day rectifiers transformer manufacturers primarily manufacture mercury-arc valves, selenium oxide, semiconductor diodes, and silicon-based.

Apart from altering AC to DC, this current is mainly used as the power source. These types of rectifiers detect radio signals and flames. Also, these are used in a varied range of applications like providing power to computers, TVs, radios, and all other relevant devices which need stable direct current supply.

Moreover, these rectifiers provide an extremely polarized voltage that is essential for welding. In such a circumstance, the supply is necessary to take control over the output current. This is fulfilled by rebuilding the diodes by using a bridge rectifier which is able to carry the output voltage which is controlled through switches.

Circuit Diagram of a Transformer Rectifier Circuit Unit

A transformer rectifier unit is used for changing alternate current to smooth direct current. The below-given diagram is that of a transformer rectifier that is used inside the battery charger of a four-wheeled vehicle.

This transformer rectifier device is using 240 alternating current voltages which are changing in around 14 volts direct current voltage for battery charging. This process can be achieved through a transformer. Initially, it step-downs the voltage from alternating current to a suitable stage and then later it converts through the fabrication of a bridge rectifier into direct current. The DC rectifier’s manufacturers mainly follow this below-given diagram.


Mostly the huge alternating current generator systems of an aircraft have a committed rectifier unit. This unit functions on a similar principle, though they are a bit more complicated.

Unitized substation manufacturers build transformer rectifier unit with the specification of 115 Volts 400 Hz 3-phase alternating current that is fixed to aircraft. It is then step-down through a 3-phase star-star wound transformer converting into 28 VDC. 

Top five features of Transformer Rectifiers 

  1. Controls
    There are various kinds of controls for rectifiers like : 
    • Analog Control
      When you do not need a specialized output, Analog Control will be the best choice. Rectifier’s transformer manufacturers design them to be reliable and straightforward. They have the ability to withstand the harshest environments. The most commonly used feature.
  • Variac or tap control
    A simple, rugged method to control electrical voltage and power.  A utility line voltage is fed to get a continuously adjustable output voltage. Generally used in industrial use rectifiers.
  • Selection control.
    Transformer rectifier’s manufacturers build selection control rectifiers (SCRs) for infrastructures that take in high voltages and currents, for situations where the device switches off automatically on change of sign. One such example is dimmer switches.

  1. Oil cooled & Air cooled & Closed-loop Water Cooling
    Air-cooled rectifiers are used in places with a low risk of corrosion. They require well-ventilated facilities.
    Oil-cooled rectifiers are very reliable and need almost no maintenance. Ideal for harsh environments, they are good for electroplating or corrosive chemical processes.
    Water-cooled rectifiers are closed-loop water cooling systems. Water is pumped into the internal water-based heat exchanger.

  2. Field-proven and long-life fan.
    Another important feature that helps in the cooling process. Rectifiers generate a significant amount of heat. Based on the environment of the installation a fan may enhance the cooling effect.

  3. Data logger and Remote Monitoring using GSM data logger.
    A very important feature helping in monitoring the health of the system. Generally implemented by transformer rectifier manufacturers in industry-level systems.

  4. Hours Run Meter or Time Totalizer
    A very important feature generally used in industrial transformers, to detect the number of hours the system is running. May be used for billing purpose.


To Conclude

There are several other features that are incorporated by the manufacturers for the ease of use and convenience and maintenance and monitoring of the rectifiers. but they are for the niche requirements and may not be considered popular.

However, it is noteworthy that rectifier’s transformer manufacturers build rectifiers for various industries and businesses. This may include: Aircraft DC Bus Power, Business aircraft, Helicopters, Local & business jets, and Aircraft used in the military etc.

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