Sunday, August 10, 2014

Polyphase Induction Motors


A typical three phase motor.
Figure 1: A typical three phase motor.
                                                     

Stator of a three phase motor.
Figure 2: Stator of a three phase motor.
Rotor of a three phase motor
Figure 3: Rotor of a three phase motor.
Stator of a three phase motor with all the coils in their slots.
Figure 4: Stator of a three phase motor with all the coils in their slots.
A portion of a three phase winding as it would appear if the slots were laid flat.
Figure 5: A portion of a three phase winding as it would appear if the slots were laid flat.

Two typical types of slots found in the stators of three phase motors.
Figure 6: Two typical types of slots found in the stators of three phase motors.
Motor using cuffed insulation in slots
Figure 7: Motor using cuffed insulation in slots.
An untaped coil used in semiclosed slots.
Figure 8: An untaped coil used in semiclosed slots.

Starting to place coils in slots.
Figure 9: Starting to place coils in slots.
The method of placing one side of each coil in slot.
Figure 10: The method of placing one side of each coil in slot.
The method of placing the sides of two coils in a slot with insulation.
Figure 11: The method of placing the sides of two coils in a slot with insulation.
A diagram of a star connection, also called a Y connection.
Figure 12: A diagram of a star connection, also called a Y connection.
A diagram of a delta connection.
Figure 13: A diagram of a delta connection.
Figure 14: A 36 coil, three phase motor with coils divided into poles.
The true shape of coils
Figure 15: The true shape of coils shown in figure 14 above.
A simplified diagram of the coils in a three phase four pole motor.
Figure 16: A simplified diagram of the coils in a three phase four pole motor.
Three groups in one pole, each group has three coils.
Figure 17: Three groups in one pole, each group has three coils.
How the coils in a group are connected together.
Figure 18: How the coils in a group are connected together.
A side view of the coil connections
Figure 19: A side view of the coil connections shown in figure 18 above.
Three coils are group wound. Connections between coils are automatically made during the winding process.
Figure 20: Three coils are group wound. Connections between coils are automatically made during the winding process.
Coils connected in twelve groups of three coils each. Note that all poles are alike.
Figure 21: Coils connected in twelve groups of three coils each. Note that all poles are alike.
Connections of groups of phase A.
Figure 22: Connections of groups of phase A.
Phase C connected exactly like phase A and connected before phase B to simplify connections.
Figure 23: Phase C connected exactly like phase A and connected before phase B to simplify connections.
The current flow in the B phase is opposite to the current flow to both the A and C phases, this is shown by the arrows under each group.
Figure 24: The current flow in the B phase is opposite to the current flow to both the A and C phases, this is shown by the arrows under each group.
A diagram similar to figure 24 above except that rectangles are used instead of coils.
Figure 25: A diagram similar to figure 24 above except that rectangles are used instead of coils.
A schematic diagram of a three phase four pole series star (1Y) motor.
Figure 26: A schematic diagram of a three phase four pole series star (1Y) motor.
A schematic diagram of a three phase four pole series delta motor.
Figure 27: A schematic diagram of a three phase four pole series delta motor.
The A phase connection in a four pole series delta motor.
Figure 28: The A phase connection in a four pole series delta motor.
The C and A phase connections in a four pole series delta motor. The end of the A phase is connected to the beginning of the C phase.
Figure 29: The C and A phase connections in a four pole series delta motor. The end of the A phase is connected to the beginning of the C phase.
A complete diagram of connections for a three phase  four pole series delta motor.
Figure 30: A complete diagram of connections for a three phase  four pole series delta motor.
Markings and connections for Y connected dual voltage motor.
Figure 31: Markings and connections for Y connected dual voltage motor.
Markings and connections for delta connected dual voltage motor.
Figure 32: Markings and connections for delta connected dual voltage motor.
Wye delta connected dual voltage motor.
Figure 33: Wye delta connected dual voltage motor.
Nine leads wye connected part winding motor. This is similar to a 9 leads dual voltage motor.
Figure 34: Nine leads wye connected part winding motor. This is similar to a 9 leads dual voltage motor.
Two methods of connecting a 9 leads delta part winding motor.
Figure 35: Two methods of connecting a 9 leads delta part winding motor.

A four pole constant torque two speed motor. The parallel star (2Y) connection is used for high speed operation, the series delta for low speed operation. T4, T5, T6 to line; T1, T2, T3 connected together, for high speed. T1, T2, T3 to line; T4, T5, T6 not connected, for low speed.
Figure 36: A four pole constant torque two speed motor. The parallel star (2Y) connection is used for high speed operation, the series delta for low speed operation. T4, T5, T6 to line; T1, T2, T3 connected together, for high speed. T1, T2, T3 to line; T4, T5, T6 not connected, for low speed.
A two speed constant horsepower motor. The series delta connection is used for high speed operation; two parallel star for low speed. T1 T2 T3 to line; T4 T5 T6 connected together for low speed. T6 T4 T5 to line; T1 T2 T3 not connected for high speed.
Figure 37: A two speed constant horsepower motor. The series delta connection is used for high speed operation; two parallel star for low speed. T1 T2 T3 to line; T4 T5 T6 connected together for low speed. T6 T4 T5 to line; T1 T2 T3 not connected for high speed.
Two speed 7 leads motor. Constant torque.
Figure 38: Two speed 7 leads motor. Constant torque.


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