Autotransformer starter working principal Auto transformer starter In this method the Auto transfo.
- 4 years ago
Auto transformer starter. An Auto transformer Starter is suitable for both star and delta connected motors. In this method, the starting current is limited by using a three-phase auto transformer to reduce the initial stator applied voltage. The figure below shows the motor with the Auto transformer starter.
Autotransformer starter working principal
Three phase induction motor
Hi guys, in this article, I am going to discuss the autotransformer starter working principle, if you are interested, keep watching the video
Autotransformer starters are commonly used with star connected AC squirrel cage motors. As high voltage AC squirrel cage motors are connected in the star to reduce the voltage stress on the winding insulation. In that case, we cannot use star-delta starters.
So, to limit the initial current or to reduce the starting stress on those motors, autotransformer start is used. Such a start consists of an auto-transformer with the necessary arrangement.
Autotransformer starter working principal
To reduce the voltage across the motor terminals during the initial period, an autotransformer-type starter typically has two autotransformers connected in an open delta. In this method of connection, only two windings are used and as shown in the figure.
This arrangement is generally used, as it is inexpensive, although currents are discontinuous during the initial period. This, however, is not very objectionable, as the current imbalance is around 15 percent and equilibrium is restored as soon as the running condition is attained.
Auto-transformer starters can be used for both star and delta connected motors. Most auto-starters are provided with 3 sets of taps, so that the voltage can be reduced to 80, 65 or 50 percent line voltage to suit the local conditions of supply.
Most squirrel cage induction motors can be successfully started at 65 percent line voltage. Where this fraction of line voltage does not provide sufficient starting torque, 80 percent of the tap can be used.
While 50 percent of the tap creates excessive voltage dip, 65 percent of the tap can be used.
At the time of starting, a low voltage is applied to the motor terminals. With a lower starting voltage, the motor draws less current and develops a lower starting torque if it is connected to a full line voltage.
When the motor achieves 80% of its normal speed, the auto-transformer is cut off and a full supply voltage is applied to the motor. The switch to make these changes from 'start' to may run may be airbreak (for small motors) or immersed in oil (for larger motors) to reduce sparking.
Autotransformer starter working
Autotransformer starter working principle
Autotransformer starter working principal
Three phase induction motor
Hi guys, in this article, I am going to discuss the autotransformer starter working principle, if you are interested, keep watching the video
Autotransformer starters are commonly used with star connected AC squirrel cage motors. As high voltage AC squirrel cage motors are connected in the star to reduce the voltage stress on the winding insulation. In that case, we cannot use star-delta starters.
So, to limit the initial current or to reduce the starting stress on those motors, autotransformer start is used. Such a start consists of an auto-transformer with the necessary arrangement.
Autotransformer starter working principal
To reduce the voltage across the motor terminals during the initial period, an autotransformer-type starter typically has two autotransformers connected in an open delta. In this method of connection, only two windings are used and as shown in the figure.
This arrangement is generally used, as it is inexpensive, although currents are discontinuous during the initial period. This, however, is not very objectionable, as the current imbalance is around 15 percent and equilibrium is restored as soon as the running condition is attained.
Auto-transformer starters can be used for both star and delta connected motors. Most auto-starters are provided with 3 sets of taps, so that the voltage can be reduced to 80, 65 or 50 percent line voltage to suit the local conditions of supply.
Most squirrel cage induction motors can be successfully started at 65 percent line voltage. Where this fraction of line voltage does not provide sufficient starting torque, 80 percent of the tap can be used.
While 50 percent of the tap creates excessive voltage dip, 65 percent of the tap can be used.
At the time of starting, a low voltage is applied to the motor terminals. With a lower starting voltage, the motor draws less current and develops a lower starting torque if it is connected to a full line voltage.
When the motor achieves 80% of its normal speed, the auto-transformer is cut off and a full supply voltage is applied to the motor. The switch to make these changes from 'start' to may run may be airbreak (for small motors) or immersed in oil (for larger motors) to reduce sparking.
Autotransformer starter working
Autotransformer starter working principle