How to change 1Ø & 3Ø motor rotation

Presented by KC Lim

Start capacitor

Run capacitor

Centrifugal switch

Run winding Start winding

Changing rotation for 1 Ø motor

Schematic single phase motor connection

Start capacitor

Run capacitor

Centrifugal switch

Run winding Start winding

Changing rotation for 1 Ø motor

When AC power apply to single phase motor, the rotor turns because of interacting of 2 different flux

Start capacitor

Run capacitor

Centrifugal switch

Run winding Start winding

Changing rotation for 1 Ø motor

What happen to motor rotation when supply polarity changed?

Start capacitor

Run capacitor

Centrifugal switch

Run winding Start winding

Changing rotation for 1 Ø motor

Instead of changing power supply, change run winding connection. What happens to the motor rotation?

Start capacitor

Run capacitor

Centrifugal switch

Run winding Start winding

Changing rotation for 1 Ø motor

Instead of changing run winding, change start winding connection. What happens to motor rotation?

Start capacitor

Run capacitor

Centrifugal switch

Run winding Start winding

Changing rotation for 1 Ø motor

What happens if both windings connection change?

Yellow Ø winding

Rotor

Red Ø winding

Blue Ø winding

Changing rotation for 3 Ø motor

0˚ 180˚90˚ 270˚ 360˚

Yellow Ø winding

Rotor

Red Ø winding

Blue Ø winding

Changing rotation for 3 Ø motor

What happens if we interchange 2 phases power supply?

Yellow Ø winding

Rotor

Red Ø winding

Blue Ø winding

Changing rotation for 3 Ø motor

What happens if we interchange 2 phases power supply?

Changing rotation for 3 Ø motor

Instead of interchange 2 phases for motor rotation, can we change one of the 3 Ø windings as per single phase motor?

Question:

Why?

Yellow Ø winding

Rotor

Red Ø winding

Blue Ø winding

Yellow Ø winding

Rotor

Red Ø winding

Blue Ø winding

Changing rotation for 3 Ø motor

0˚

150˚

180˚

90˚

120˚

Let focus on motor’s magnetic flux at 90˚, 120˚, 150˚, and 180˚ only

Changing rotation for 3 Ø motor

0˚

150˚

180˚

90˚

120˚

50%

100%

86.6%

50%

86.6%

0% 100

%

0%

86.6%

86.6%

Intensity of the flux on particular phases at different waveform angle

Changing rotation for 3 Ø motor

0˚

90˚

50%

100%

120˚

120˚

120˚

Stator

100%50%50%

150%

Resulting flux

Changing rotation for 3 Ø motor

0˚ 120˚

86.6%

0%

86.6%

Stator

86.6%

86.6%

150%

30˚

Resulting flux

Changing rotation for 3 Ø motor

0˚

150˚

Stator

50%

50%

100%150%

50%

100%

60˚

Resulting flux

Changing rotation for 3 Ø motor

0˚ 180˚

86.6%

0%

86.6%

Stator

86.6%

86.6%

150%

90˚

Resulting flux

Changing rotation for 3 Ø motor

Stator

0˚ 180˚90˚ 270˚ 360˚

90˚120˚150˚180˚

Summary

Resulting flux

150%

150%

150%

150%

Changing rotation for 3 Ø motor

Stator

0˚ 180˚90˚ 270˚ 360˚

Resulting flux

Changing rotation for 3 Ø motor

Yellow Ø winding

Rotor

Red Ø winding

Blue Ø winding

What happen when 1 winding connection is changed?

Changing rotation for 3 Ø motor

0˚

90˚

50%

100%

Stator

100%

50%50%

50%

Resulting flux

Changing rotation for 3 Ø motor

0˚ 120˚

86.6%

0%

86.6%

Stator

86.6%

86.6%

150%

86.6%

60˚

Resulting flux

Changing rotation for 3 Ø motor

0˚

150˚

Stator

50%50%

100%161.7%

50%

100%

62.4˚

Resulting flux

Changing rotation for 3 Ø motor

0˚ 180˚

86.6%

0%

86.6%

Stator

86.6%

86.6%

150%

90˚

Resulting flux

Changing rotation for 3 Ø motor

Stator

0˚ 180˚90˚ 270˚ 360˚

90˚120˚150˚180˚

Summary

Resulting flux

50%

150%

86.6

%

161.

7%

Changing rotation for 3 Ø motor

Supply waveform

angle

Changing two phases Changing one winding

Resultant flux

Flux angle Resultant flux

Flux angle

90˚ 150% 0˚ 50% 0˚

120˚ 150% 30˚ 86.6% 60˚

150˚ 150% 60˚ 161.7% 62.4˚

180˚ 150% 90˚ 150% 90˚

Conclusion:Changing one winding could cause high starting current because of less resulting flux magnitude and the flux rotation angle is not smooth enough

Changing rotation for 3 Ø motor

Yellow Ø winding

Rotor

Red Ø winding

Blue Ø winding

What happen when 2 windings are changed?

Changing rotation for 3 Ø motor

0˚

90˚

50%

100%

Stator

100%

50%

50%132.3%

40.9˚

Resulting flux

Changing rotation for 3 Ø motor

0˚ 120˚

86.6%

0%

86.6%

Stator

86.6%

86.6%

86.6%60˚

Resulting flux

Changing rotation for 3 Ø motor

0˚

150˚

Stator

50%

50%100%

50%

50%

100%

120˚

Resulting flux

Changing rotation for 3 Ø motor

0˚ 180˚

86.6%

0%

86.6%

Stator

86.6%

86.6%

86.6%

180˚

Resulting flux

Changing rotation for 3 Ø motor

Supply waveform

angle

Changing two windings

Resultant flux

Flux angle

90˚ 50% 40.9˚

120˚ 86.6% 60˚

150˚ 161.7% 120˚

180˚ 150% 180˚

Conclusion:Changing both windings could also cause high starting current

Changing rotation for 3 Ø motor

Yellow Ø winding

Rotor

Red Ø winding

Blue Ø winding

What happen when 3 windings are changed?

Changing rotation for 3 Ø motor

Stator

180˚90˚ 270˚ 360˚

Conclusion:Changing 3 windings, nothing different. The rotation remains unaltered. The resultant flux is the same as original 3 phase windings connection

Resulting flux

Thank You For Your Attention