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 E2 Motors and Motor Starting (Modified) #1 Fan Motors.

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Presentation on theme: " E2 Motors and Motor Starting (Modified) #1 Fan Motors."— Presentation transcript:

1  E2 Motors and Motor Starting (Modified) #1 Fan Motors

2  © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 2 Basic Electric Motor Stator –Stationary electromagnet Rotor –Rotating magnet Movement of the rotor –Rotates by repulsion and attraction of stator

3  © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 3 ROTOR (with shaft) STATOR (with windings) Exploded View of Motor

4  © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 4 Two-pole stator motor N NS _ + S N S Stator (Stationary) When stator is energized the rotor will make a half turn with each half of current cycle Rotor (Rotates) Polarity reverses (N to S) on stator Stator repels & attracts rotor into motion

5  © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 5 Second half of cycle NS + _ N S The alternating current now changes direction N S Polarity reverses (N to S) on stator Stator continues motion by repelling and attracting

6  © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 6 Motor Starting All motors need a phase shift to start rotation

7  © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 7 Stator S N Rotor S N Equal and opposite attraction Opposite attraction Rotor will NOT move Power applied to stators Motor Tries to Start

8  © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 8 Stator S N 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 A phase shift causes rotation A Phase Shift is Needed

9  © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 9 Shaded-Pole Motors Low starting torque Low efficiency Low cost

10  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Examples of Shaded-Pole Motors

11  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Rotation toward the Shaded Pole SN NS

13  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Shaded-Pole Motor Wiring GREEN GROUND BLACK LINE

14  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Changing Motor Rotation Shaded-pole motors can be reversed: –First, turn stator around –Second, turn blade around

15  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Interesting Motor Fact Motor efficiency: A 100 watt 50% efficient motor will put out 50 watts of work, and 50 watts of heat.

16  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Shaded-pole C-frame Motor

17  © 2005 Refrigeration Training Services - E2#1 Fan Motors v To Reverse Rotation ` ` Turn Stator Around

18  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Turn fan blade around Rotation is now reversed `

19  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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 Common High Speed Medium Speed Low Speed

20  © 2005 Refrigeration Training Services - E2#1 Fan Motors v BLACK LINE Shaded-Pole 3-Speed Motor Wiring GREEN GROUND BLACK-HIGH BLUE-MED RED-LOW LINE Common Wire is White (115v) or Black (230v)

21  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Start A Split Phase Motor is a Two-pole stator motor … Run with Start Windings added TO RUN WINDINGS TO START WINDINGS R C S

23  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Ω Ω Ω RUN WINDING Start & Run Winding Resistances R START WINDING S C COM V/   V AC DC

24  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Windings of a split phase motor

25  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Split Phase Motor LINE RUN WINDING START WINDING CR S This motor needs power to the run winding to run This motor needs power to the start winding to start This motor needs a start winding for a phase shift

26  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Split Phase Motor with Centrifugal Switch LINE RUN WINDING START WINDING S CR Centrifugal switch opens start winding

28  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v To Start Winding Motor with Centrifugal Switch Start winding energized Motor Speed Increases Weights shift, disk moves back Centrifugal Switch From Run Winding Contacts Open Disk Before starting, disk pushes bar, closing contacts

30  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v PSC Motor with run capacitor Low Starting Torque Low to Medium Cost Medium Efficiency

32  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Split Phase Motor + Run Cap = PSC Motor RUN WINDING START WINDING R C S Run Capacitor

33  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v PSC Motor Wiring Diagram GREEN GROUND BLACK LINE BROWN CAPACITOR

35  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Courtesy of Copeland 7200  2 = 3600 RPM Two Pole Motor Windings

38  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Courtesy of Copeland  4 = 1800 RPM Four Pole Motor

39  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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: Pole motor: Pole motor: Pole motor:

40  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Single-Speed PSC Motor RUN WINDING START WINDING R C S Run Capacitor

42  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Single-Speed PSC Motor RUN WINDING START WINDING R C S Run Capacitor

43  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Multi-speed PSC Motor RLRL RMRM RUN WINDING START WINDING R C S RHRH High Speed Medium Speed Low Speed

44  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Speed PSC Motor Wiring Diagram GREEN GROUND BROWN BLACK LINE BLACK-HIGH BLUE-MED RED-LOW LINE

45  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Common Wire High Speed (black) Medium Speed (blue) Low Speed (red) PSC 3-speed Motor Leads for changing motor rotation Run Capacitor Leads

47  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Three Phase Motors High starting torque High efficiency Medium to high cost

48  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Three Phase Motors

49  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Three Phase Motor Starting No start windings or capacitors needed High torque because the windings are 120° out of phase

50  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Ø Motor – Wye Connections 208 V T1 L1 L3 L2 T2T3

51  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Ø Motor – Delta Connections T1 T3 T2 L1 L3 240 V L2 240 V

52  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Describing Common Motors Motor descriptions include the following information: –Type –Enclosure –Mounting

53  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Common Motor Types

54  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Motor Enclosure Types Open Dripproof Totally enclosed Totally enclosed fan cooled

55  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Open Enclosure Types Open Dripproof Totally Open Clean and Dry Locations Note: Prevents direct entry of moisture Clean and Mostly Dry Locations

56  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Motor Mounting Some of the more common mounts: –Rigid –Cradle –Belly band –Stud –C-frame –Unit bearing

58  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Cradle Mount

59  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Rigid Mount Motor housing is welded to the base

60  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Belly Band Mounting Motor slides into ring. Then band is tightened

61  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Stud Mounts Studs are bolted to fan guard or housing.

62  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Other Motor Mounting Styles Unit bearing C-frame

63  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Motor Nameplate Nameplates contain essential information

64  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Motor Nameplate explained

65  © 2005 Refrigeration Training Services - E2#1 Fan Motors v Motor Nameplate wiring diagram

66  © 2005 Refrigeration Training Services - E2#1 Fan Motors v 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  © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 67


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