1. E2 Motors and Motor Starting (Modified)
ICT
BASIC ELECTRICAL
TECH 100
E2 Motors and Motor Starting (Modified)
#1 Fan Motors

2. Basic Electric Motor Stator Rotor Movement of the rotor
Stationary electromagnet
Rotor
Rotating magnet
Movement of the rotor
Rotates by repulsion and attraction of stator

3. Exploded View of Motor
STATOR
(with windings)
ROTOR
(with shaft) ]

4. _ + Two-pole stator motor N S S N N S Stator Rotor (Stationary)
(Rotates) N S S N N S
Polarity reverses (N to S) on stator
Stator repels & attracts rotor into motion _
When stator is energized the rotor will make a half turn
with each half of current cycle +

5. _ + Second half of cycle N S S N N S
Stator continues motion by repelling and attracting
Polarity reverses (N to S) on stator _ +
The alternating current now
changes direction

6. Motor Starting
All motors need a phase shift to start rotation

7. Motor Tries to Start N S Power applied to stators S
Equal and opposite attraction
Rotor S N
Opposite attraction
Rotor will NOT move
Equal and opposite attraction S
Stator

8. A Phase Shift is Needed N S A phase shift causes rotation S
Stator N
A phase shift causes rotation
Rotor S N
A magnetic field is
formed at a slightly
different angle
This phase shift can be caused by:
A shaded pole
A start winding
A capacitor
3 separate phases S
Stator

9. Shaded-Pole Motors
Low starting torque
Low efficiency
Low cost

10. Examples of Shaded-Pole Motors

11. Starting a Shaded-Pole Motor
Each pole has a copper band attached
The shaded-pole provides the phase shift needed to start rotation
Usually impedance protected
A stalled blade will not cause burned windings

12. Rotation toward the Shaded Pole

13. Shaded-Pole Motor Wiring
COMMON LINE
BLACK LINE
GREEN GROUND

14. Changing Motor Rotation
Shaded-pole motors can be reversed:
First, turn stator around
Second, turn blade around

15. Interesting Motor Fact
Motor efficiency:
A 100 watt 50% efficient motor will put out 50 watts of work, and 50 watts of heat.

16. Shaded-pole C-frame Motor

17. To Reverse Rotation
Turn Stator Around ` `

18. Rotation is now reversed
Turn fan blade around
Rotation is now reversed `

19. Multi-speed Shaded-Pole Motors
Speed depends on winding resistance
Low speed: most resistance
High speed: least resistance
Motor speed is based on where power is connected into the winding
High Speed
Medium Speed
Low Speed
Common

20. Shaded-Pole 3-Speed Motor Wiring
COMMON LINE
Common Wire is White (115v) or Black (230v)
BLACK-HIGH
BLACK LINE
LINE
BLUE-MED
RED-LOW
GREEN GROUND

21. Split Phase Motors Have two separate windings, a run and a start
The start winding provides the phase shift for starting
More efficient and have more torque than shaded pole motors

22. A Split Phase Motor is a Two-pole stator motor …
with Start Windings added
Start
Run
TO RUN
WINDINGS R C
TO START
WINDINGS S

23. Start & Run Winding Resistances
START WINDING
COM
V/  V AC DC S Ω Ω Ω R

24. Windings of a split phase motor
Run Windings
Start Windings

25. Split Phase Motor S
This motor needs power to the start winding to start C R
START WINDING
RUN WINDING
This motor needs power to the run winding to run
A split phase motor is the basic design for motors used in all HVACR applications.
The run winding uses heavy wire, while the finer wire of the start winding provides the resistance and phase shift necessary to start the motor.
Once the motor is started we need to take the start winding out of the circuit.
We can accomplish this with either a current relay or a potential relay.
This motor needs a start winding for a phase shift
LINE

26. Fan Motor with Centrifugal Switch
A mechanical switch is used to de-energize the start winding
The switch is attached to the motor shaft
After the motor starts, centrifugal force opens the switch
The start winding circuit remains open as long as the motor is running

27. Split Phase Motor with Centrifugal Switch
Centrifugal switch opens start winding C R S
START WINDING
RUN WINDING
A split phase motor is the basic design for motors used in all HVACR applications.
The run winding uses heavy wire, while the finer wire of the start winding provides the resistance and phase shift necessary to start the motor.
Once the motor is started we need to take the start winding out of the circuit.
We can accomplish this with a centrifugal switch (above) on an open motor, like a fan motor.
However enclosed motors, such as compressor motors, use switches like current relays and potential relays. If the switches were located inside the compressor with the motor windings a spark from the contacts could cause the oil and refrigerant vapors to explode.
LINE

28. Fan Motor with Centrifugal Switch
The next slide is a picture of a fan motor with the motor cover removed
The centrifugal switch is attached to the motor shaft
The switch contacts are attached to the end bell (motor cover)

29. Motor with Centrifugal Switch
Weights shift, disk moves back
Motor Speed Increases
Start winding energized
Before starting, disk pushes bar, closing contacts
Contacts Open
To Start Winding
Centrifugal Switch
Disk
From Run Winding

30. Permanent Split Capacitor Motors
A run capacitor is “permanently” wired into the start winding circuit
The capacitor provides partial voltage to the start winding, during start and run

31. PSC Motor with run capacitor
Low Starting Torque
Low to Medium Cost
Medium Efficiency

32. Split Phase Motor + Run Cap = PSC Motor
RUN WINDING
START WINDING S R
Run Capacitor

33. Interesting Motor Fact
A PSC motor with a shorted run capacitor will act like an overloaded motor.
A PSC motor with an open run capacitor will not start.

34. PSC Motor Wiring Diagram
COMMON LINE
BLACK LINE
BROWN W/ WHITE
BROWN
GREEN GROUND
CAPACITOR

35. Motor Speeds
The synchronous speed of a motor can be determined by the number of its poles.
The more poles, the lower the speed.

36. Calculating ‘Synchronous’ Motor Speeds
One cycle has two current flow reversals
60 cycles has 120 flow reversals
Speed = (60 Hz x 120 reversals) ÷ Poles
Example: 7200 ÷ 2 Motor poles = 3600 RPM

37. Two Pole Motor Windings
2 Run
Windings
2 Start
Windings
Two Pole Motor Windings
Here is a 2-pole stator that runs at 3,500 rpm.
The large red windings are the run windings.
The small green windings are the start windings.
They are smaller for two reasons, one is because the smaller wire resists the flow of electrons which changes the phasing slightly. The second reason is that the small windings are not in the circuit for over 3 seconds.
The start winding has more turns and smaller wire than the run winding.
Courtesy of Copeland
7200  2 = 3600 RPM

38. Four Pole Motor 4 Run Windings 1 2 1 4 Start Windings 4 2
7200  4 = 1800 RPM
Here is a 4-pole stator with the end turns painted so that the poles of the main winding and the auxiliary winding are easier to see. 3 4 3
Courtesy of Copeland

39. Actual ‘Rotor’ Motor Speed
Slippage is the loss of speed from motor load
The ‘rotor’ speed is less than the ‘synchronous’ speed.
Common motor speeds:
Synchronous: ROTOR:
2 Pole motor:
4 Pole motor:
6 Pole motor:
8 Pole motor:

40. Multi-Speed PSC Motors
Actually they are “Multi-horsepower”
The windings are tapped so the motor is weaker, running slower under load
Example of a 3-speed 1/3 HP motor:
High speed is 1/3 HP
Medium speed is 1/4 HP
Low speed is 1/6 HP

41. Single-Speed PSC Motor
RUN WINDING
START WINDING S R
Run Capacitor

42. Single-Speed PSC Motor
RUN WINDING
START WINDING R C S
Run Capacitor

43. Multi-speed PSC Motor High Speed Medium Speed Low Speed RH C RM S R RL
START WINDING
RUN WINDING S R
Low Speed RL

44. 3-Speed PSC Motor Wiring Diagram
COMMON LINE
BLACK-HIGH
BLACK LINE
LINE
BLUE-MED
RED-LOW
BROWN W/ WHITE
BROWN
GREEN GROUND

45. Interesting Motor Fact
Multi-speed motors must be under a load to change speeds
Example: A multi-speed blower removed from the blower compartment will run at high speed, no matter which speed tap is used

46. Leads for changing motor rotation
PSC 3-speed Motor
Leads for changing motor rotation
Run
Capacitor Leads
Common Wire
Low Speed (red)
Medium Speed (blue)
High Speed (black)

47. Three Phase Motors High starting torque High efficiency
Medium to high cost

48. Three Phase Motors

49. Three Phase Motor Starting
No start windings or capacitors needed
High torque because the windings are 120° out of phase

50. 3Ø Motor – Wye ConnectionsL1
208 V
208 V T1 T3 T2 L2
208 V L3

51. 3Ø Motor – Delta Connections
240 V
240 V T3 T2 L2
240 V L3

52. Describing Common Motors
Motor descriptions include the following information:
Type
Enclosure
Mounting

53. Permanant Split Capacitor
Common Motor Types
Shaded Pole
Split Phase
Permanant Split Capacitor
Three Phase

54. Motor Enclosure Types Open Dripproof Totally enclosed
Totally enclosed fan cooled

55. Open Enclosure Types Totally Open Open Dripproof
Note: Prevents direct entry of moisture
Clean and Mostly Dry Locations
Clean and Dry Locations

56. Enclosed Type Motors Totally Enclosed Air Over
Totally Enclosed Fan Cooled
Cooling from system air passing over the motor body
Cooling from fan forced air passing over the motor body
Totally Enclosed are good for wet and dirty conditions

57. Motor Mounting Some of the more common mounts: Rigid Cradle Belly band
Stud
C-frame
Unit bearing

58. Cradle Mount

59. Motor housing is welded to the base
Rigid Mount
Motor housing is welded to the base

60. Motor slides into ring. Then band is tightened
Belly Band Mounting
Motor slides into ring. Then band is tightened

61. Studs are bolted to fan guard or housing.
Stud Mounts
Studs are bolted to fan guard or housing.

62. Other Motor Mounting Styles
Unit bearing
C-frame

63. Motor Nameplate
Nameplates contain essential information

64. Motor Nameplate explained
MODEL
1/2 HP 1 PH
1075/3SPD
RPM 60 HZ
115
VOLT
9.00
AMP
USE 5.00 MFD 370 V. CAPACITOR
Motor Nameplate explained

65. Motor Nameplate wiring diagram
LINE
BROWN
YELLOW
PURPLE
ORANGE
BLUE
N.P.24X327501
RED
BROWN WHITE LO
MED HI
CAPACITOR
BLACK
MOTOR SHIPPED AS
SHOWN FOR CCW
ROTATION FOR CW
CHANGE YELLOW &
ROTATION INTER
ORANGE LEADS
Motor Nameplate wiring diagram

66. Interesting Motor Facts
An overloaded motor (too small for the job):
Lower speed, amperage above 10% of RLA, and overheating
An under-loaded motor (too big for the job):
Little change in speed, amperage 25% below RLA, and overheating

67. THANKS FOR YOUR
ATTENTION