Chapter 28, Problem 1SQ

To determine

Explain the process how 230/460-volt motor is used as a part winding motor.

Explanation of Solution

Part winding motor:

The part winding motor has two sets of identical windings which are connected in parallel with each other. The two identical windings are energized in a sequence to produce the reduced starting current and the reduced starting torque.

Dual voltage motor:

The dual voltage motor has two sets of windings (not identical) which are connected either in parallel or in series. When the 230/460-volt motor operates with the part winding starter, it is intended to connect the two sets of windings in parallel (voltage ratio is 1:2). An each set of windings is connected either in Y or delta connection.

The dual voltage motor can operate with different power supply voltages. When the dual voltage motor’s two sets of windings are connected in parallel, the motor can operate with low voltage connection. When the windings are connected in series, the motor can operate with high voltage.

230/460-volt motor as a part winding motor:

230/460-volt dual voltage motor can be used as a part winding motor with low voltage connection. At the starting of the motor, the low voltage supply is connected to the one set of winding. As soon as the motor reaches to the normal speed, apply the power to the other set of winding (the other winding from the parallel windings) in the running conditions for the normal running operation of the motor. The motor runs with reduced starting current and the reduced starting torque after both the windings are energized in a sequence.

The part winding starter is a reduced voltage starter and used in the starting process of the 230/460-volt part winding motor.

Refer to Figure 28.3 in textbook where the 230/460-volt motor can be used as a part winding motor with low voltage connection. One set of winding terminals ${\text{T}}_{\text{1}}$ ,${\text{T}}_2$, and ${\text{T}}_3$ to the starting contacts ${\text{L}}_{\text{1}}$ ,${\text{L}}_2$ and ${\text{L}}_3$. The other set of winding terminals ${\text{T}}_7$ ,${\text{T}}_8$, and ${\text{T}}_9$ are connected to the running starter (R) contacts. The Y connected two sets winding is used in part winding motor with low voltage connection. The terminals ${\text{T}}_4$ ,${\text{T}}_5$, and ${\text{T}}_6$ are connected together and act as a center of second set of winding.

Figure 1 shows the low voltage connection of a part winding motor.

Conclusion:

Thus, the 230/460-volt motor can be used as a part winding motor.