Autotransformer application and use

  Autotransformers are special power transformers wound with one winding with taps. The prefix "auto" here does not define any automatic process, but indicates that only one coil is involved, which works alone. These transformers are an excellent choice for low voltage applications.

  It must be borne in mind that it is most rational to use them with small transformation ratios. With an increase in the transformation ratio, for example, 220V-12V, the autotransformer no longer makes sense to use.


 In energy - Autotransformers are widely used in power circuits. They work perfectly at various voltage classes, up to 132 kV for power transmission. In long power lines, autotransformers with automatic regulation are used to connect high-voltage networks with networks of similar voltage. The transformation ratio in such devices usually does not exceed 2 - 2.5. 

  In audio systems - Autotransformers are used in audio devices that adapt loudspeakers to the constant voltage of an audio distribution system and for impedance matching.

  In rail transport - Autotransformers are used on railways to connect the overhead wire to the rail and to the power conductor to increase the effective transmission distance, as well as reduce interference induced in external equipment.

  In industry-power three-phase autotransformers are used to reduce the starting current of electric motors.

  At home- as part of servo-driven mechanical voltage stabilizers. This type of stabilizer is difficult to manufacture and cost. However, it is most accurate when changing the voltage, because. allows you to change the voltage in small steps and, most importantly, smoothly.

Below are several options for using autotransformers.

  Testing an electronic device after repair - after repair, to test the device it is necessary to apply the rated voltage to it. The laboratory autotransformer (LATR) allows supplying reduced voltage and monitoring the test process. If a high voltage is applied immediately, without testing, the device will burn out. You can also connect an old amplifier or radio using an autotransformer. Electrolytic capacitors can be recovered by applying reduced voltage to them.

  To adjust the AC supply voltage - The autotransformer can easily adjust the output voltage of the AC power supply. Currently, autotransformers are used to change the voltage supplied to electric motors. This allows the rotation speed to be adjusted. They can be used in the same way in heating systems. Where the change in the heating of the coil is achieved by changing the voltage on the autotransformer. For example, in devices for cutting plates made of styrodur and foam, it is possible to regulate the voltage and, accordingly, maintain the operating temperature.

  To compensate for voltage drops in power lines- long power lines suffer from a voltage drop at the consumer, with a large power take-off. An autotransformer can compensate for this voltage loss.

In unregulated DC power supply design  - An unregulated DC power supply can be built using an autotransformer. However, this should only be done when it is safe to do so. Autotransformers do not allow galvanic isolation of high and low voltage circuits. They are electrically connected. Thus, the risk of electric shock increases.


If you are an equipment developer and you need to use an autotransformer in your device, please contact us for advice !!!

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