Motor Starter Auto Transformer

Motor starting autotransformers 3-phase asynchronous motors draw a current above their nominal current at the first start. This high current drawn can cause problems in the network, circuit and motor. Motor starting autotransformers are used to limit the inrush current drawn by the motors at the start of the motor in order to prevent possible problems.

In the Star/Delta starting method, the starting current cannot be reduced below 33.3% of the normal operating current. With motor starting autotransformers, the starting current is reduced to 50% ~ 65% of the normal operating current. Thus, the starting current of the motor will be reduced below the rated current and the protection devices will not stop the operation of the system.

The voltage taken from the secondary end of the motor starting autotransformer, which is wound gradually, is drawn to values lower than the operating voltage of the motor. Thus, the starting current of the motor is reduced by applying a low voltage to the motor. Torque is also lower. After the motor starts and reaches the nominal operating state, the voltage terminal is transferred to the input, allowing the motor to switch to the nominal operating mode. In this way, the transformer is deactivated until the next start up.

Thanks to this stall operation method, the transformer can be designed in much smaller dimensions than normal. Artsan motor starting autotransformers are designed to start 10 times per hour, with a maximum of 3 consecutive starts.


Nominal Operating Voltage: At desired value up to 6600V.
Voltage outputs: 0-70% Different voltage values can be added optionally.
Takeoff time: 6 seconds
Thermal Protection : 132 º
Working regime : 10 times per hour, maximum 3 times in succession
Special design can be made according to different working regimes.
Standard: EN 61558-2-13, IEC 60076


High permeability iron core
High quality copper or aluminum winding
Low loss, high efficiency
Varnish under vacuum against moisture and noise.
Compliance with EN 61558-2-13, CE mark
Production under the ISO 9001:2008 system.