Discuss the use of taps in autotransformer starters.
What will be an ideal response?
Many autotransformer starters contain taps that can be set for 50 percent, 65 percent, or 80 percent of the line voltage. Reducing the voltage applied to the motor not only reduces the amount of in-rush current, but also reduces the motor torque. If 50 percent of the normal voltage is connected to the motor, the in-rush current will drop to 50 percent also. This will produce a torque that is 25 percent of the value when full voltage is connected to the motor. If the motor torque is insufficient to start the load when the 50 percent tap is used, the 65 percent or 80 percent taps are available.
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