Rectifier Transformer

 

      Generally, rectifier transformer is used as a source of power for rectifier bridges in various applications like DC arc furnace. Depending on the application requirement, the voltage is stepped down by this transformer to between 500 and 3300 V.

      The primary side of rectifier transformer is connected with AC power; thus, it is called line side. The secondary side is connected with rectifier; thus it is called DC side. The rectifier transformer is shown in Fig.1.

      In this, the rectifier is generally placed inside the transformer tank. However, sometimes it may even be placed outside the tank. But if the quality and the performance of the rectifier transformer unit are considered, then the immersed option is better than when the unit is outside the tank because the oil is used as cooling medium, which is 10 times  more effective than air. Furthermore, the corrosion problem is totally eliminated.

      The winding used in the rectifier transformer is of sandwich type. The various tappings are provided on the windings or sometimes a tap changer is used for this purpose. These tappings are further divided into more groups and these groups are perfectly balanced on the DC  winding side by making group A and B of double-star type. The combination is made such that the magnetic coupling remains small. The series parallel changer and tap changer provided at the side of the windings are controlled on the floor by a hand wheel. The DC winding lead is divided into both sides of the winding for each of the group A and B and is located in a compact manner.

Salient Features of Rectifies Transformer 

1. Various model are variable, so a wide range of selection is obtained. 

2. There is an option of selecting from free cooling, forced cooling, or fan cooling transformer as per load requirement. 

3. It is provided with voltage regulation. 

4. It has clean input power with low harmonic distortion. 

5. It provides output current ranging from 50A to 400A. 

6. It is highly efficient and requires less maintenance. 

Advantages of Rectifier Transformer 

      The main advantage of rectifier transformer is that it is used for supplying 28 V DC busses to which emergency back-up batteries are connected. 

Disadvantages of Rectifier Transformer 

      In a conventional system, the transformer and rectifier systems are separate units. Hence it is possible to increase the DC voltage output  by merely adding a booster transformer to the existing one. This is not possible in the rectifier transformer combined unit. 

Application of Rectifier Transformer 

      Rectifier transformer are widely used in various fields like: 

1. Military aircraft and fighters 

2. Commercial transport aircraft 

3. Helicopters 

4. Trainers 

5. Avionics