What is a booster transformer?
A booster transformer is used at end of the transmission line to increase the voltage to the desired value. The main function of the booster transformer is to compensate for the voltage drop in transmission when the transmission line is away from the source. A booster transformer is a device that is used to boost the voltage from the low level to the desired level.
The secondary of regulating transformer is connected to the primary of booster transformer in such a way that voltage injected in the transmission is in phase with the supply voltage.
A voltage at point AA is maintained constant by changing taps of the main transformer. Due to long-distance and tapping load between the point AA and BB voltage drop takes place in the transmission line.
Construction of booster transformer
The booster transformer is consist of primary and secondary windings. The secondary winding of the booster transformer is connected in series with the transmission line whose voltage shall be controlled and the primary of the booster transformer is supplied from the secondary of the regulating transformer.
The magnitude of the transmission line voltage is regulated by changing that tapping on the secondary side of regulating transformer.
Working of Booster transformer
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| Booster Transformer |
The voltage at point BB is controlled by using the regulating transformer and booster transformer. The magnitude of voltage that is injected into the transmission line is changed at the desired value by changing the taps of regulating transformer.
The ratings of regulating transformer are a fraction of the main transformer and it is given by
KVA x rating of booster = Load KVA x percentage boost in voltage
The rating of booster transformer is given by
For single-phase booster transformer
(Line current x boost voltage/1000)KVA
For three-phase booster transformer
(√3 x Line current x boost voltage/1000) KVA
In booster transformer, regulating transformer is unit is independent of the main unit of the transformer.
Advantages of booster transformer
1. The booster transformer is used in railway traction for eliminating the flow of stray currents. The stray current causes interference with the communication lines and also damage the electronic equipment of trains.
2. Booster transformers are also used for compensating the voltage drop in the feeder when it is far away from the source.
3. The booster transformer is used in the electrical railway to collect the return current from the rails and also the earth to the return conductor.
4. The booster transformer is used in the electrical railway to collect the return current from the rails and also the earth to the return conductor.
5. The booster transformer is used in UPS to make the output voltage of UPS constant.
Disadvantages of booster transformer
1. The booster transformers are more expensive than the on-load tap changing transformer.
2. For installation of booster transformer more floor area is required.
3. The booster transformer method of voltage is not more efficient there are more losses in the booster transformer.
4. The booster transformer also effects on voltage regulation. when we use booster transformer voltage drop is 10 % and without booster transformer voltage drop is 2.5 %. So voltage drop is increased when we use booster transformer.