E2 Motors and Motor Starting #1 Fan Motors
Basic Electric Motor Stator Stationary electromagnet Rotor Rotating magnet Movement of the rotor Rotates by repulsion and attraction of stator 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 2
Exploded View of Motor STATOR (with windings) ROTOR (with shaft) 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 3
Two-pole stator motor Stator (Stationary) Rotor (Rotates) Polarity reverses (N to S) on stator SN N S NS Stator repels & attracts rotor into motion + _ When stator is energized the rotor will make a half turn with each half of current cycle 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 4
Second half of cycle Stator continues motion by repelling and attracting SN N S NS Polarity reverses (N to S) on stator + _ The alternating current now changes direction 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 5
Motor Starting All motors need a phase shift to start rotation 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 6
Motor Tries to Start Stator Equal and opposite attraction Equal and opposite attraction N S Rotor N S Stator Power applied to stators Opposite attraction Rotor will NOT move 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 7
A Phase Shift is Needed Stator N A phase shift causes rotation This phase shift can be caused by: A shaded pole A start winding A capacitor 3 separate phases S Rotor N S Stator A magnetic field is formed at a slightly different angle 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 8
Shaded-Pole Motors Low starting torque Low efficiency Low cost 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 9
Examples of Shaded-Pole Motors 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 10
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 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 11
Rotation toward the Shaded Pole N S N S 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 12
Shaded-Pole Motor Wiring BLACK LINE GREEN GROUND 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 13
Changing Motor Rotation Shaded-pole motors can be reversed: First, turn stator around Second, turn blade around 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 14
Interesting Motor Fact Motor efficiency: A 100 watt 50% efficient motor will put out 50 watts of work, and 50 watts of heat. 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 15
Shaded-pole C-frame Motor 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 16
To Reverse Rotation Turn Stator Around 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 17
Turn fan blade around Rotation is now reversed 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 18
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 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 19
Shaded-Pole 3-Speed Motor Wiring Common Wire is White (115v) or Black (230v) BLACK-HIGH BLUE-MED LINE LINE RED-LOW GREEN GROUND 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 20
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 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 21
A Split Phase Motor is a Two-pole stator motor with Start Windings added Start Run Run TO RUN WINDINGS TO START WINDINGS R C S Start 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 22
Start & Run Winding Resistances C S Ω Ω V AC R DC COM V/Ω 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 23
Windings of a split phase motor 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 24
Split Phase Motor S This motor needs power to the start winding to start C R START WINDING This motor needs a start winding for a phase shift RUN WINDING This motor needs power to the run winding to run LINE 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 25
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 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 26
Split Phase Motor with Centrifugal Switch Centrifugal switch opens start winding S C R START WINDING RUN WINDING LINE 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 27
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) 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 28
Motor with Centrifugal Switch Start winding energized Motor Speed Increases Weights shift, disk moves back Before starting, disk pushes bar, closing contacts From Run Winding Contacts Open To Start Winding Disk Centrifugal Switch 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 29
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 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 30
PSC Motor with run capacitor Low Starting Torque Low to Medium Cost Medium Efficiency 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 31
Split Phase Motor + Run Cap = PSC Motor C S R Run Capacitor 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 32
Interesting Motor Fact A PSC motor with a bad run capacitor will act like an overloaded motor 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 33
PSC Motor Wiring Diagram BLACK LINE BROWN GREEN CAPACITOR GROUND 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 34
Motor Speeds The synchronous, or nominal speed of a motor can be determined by the number of its poles The more poles, the lower the speed 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 35
Two Pole Motor Windings 7200 2 = 3600 RPM Courtesy of Copeland 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 36
Calculating 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 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 37
1 1 2 Four Pole Motor 4 4 7200 4 = 1800 RPM 3 2 3 Courtesy of Copeland 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 38
Actual Motor Speed Slippage is the loss of speed from motor load The actual speed is less than the calculated speed Common motor speeds: Calculated: Actual: 2 Pole motor: 3600 3450 4 Pole motor: 1800 1750 6 Pole motor: 1200 1050 8 Pole motor: 900 850 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 39
Multi-Speed Split Phase 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 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 40
Single-Speed PSC Motor C S R Run Capacitor 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 41
Single-Speed PSC Motor C S R Run Capacitor 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 42
Multi-speed PSC Motor R H High Speed C R M Medium Speed S R R L Low Speed 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 43
3-Speed PSC Motor Wiring Diagram BLACK-HIGH BLUE-MED LINE LINE RED-LOW BROWN GREEN GROUND 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 44
Single-Speed CSCR Motor C S Run Capacitor R Start Capacitor 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 45
Multi-speed CSCR Motor R H High Speed C R M Medium Speed S R R L Low Speed 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 46
Capacitor Start Capacitor Run 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 47
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 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 48
PSC 3-speed Motor Leads for changing motor rotation Run Capacitor Leads Low Speed (red) Medium Speed (blue) High Speed (black) Common Wire 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 49
Three Phase Motors High starting torque High efficiency Medium to high cost 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 50
Three Phase Motors 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 51
Three Phase Motor Starting No start windings or capacitors needed High torque because the windings are 120 out of phase 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 52
3Ø Motor Wye Connections L1 T1 208 V 208 V T3 T2 L2 208 V L3 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 53
3Ø Motor Delta Connections T1 L1 240 V T3 T2 L2 240 V 240 V L3 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 54
Describing Common Motors Motor descriptions include the following information: Type Enclosure Mounting 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 55
Common Motor Types 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 56
Motor Enclosure Types Open Dripproof Totally enclosed Totally enclosed fan cooled 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 57
Open Enclosure Types Open Dripproof Totally Open Note: Prevents direct entry of moisture Clean and Mostly Dry Locations Clean and Dry Locations 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 58
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 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 59
Motor Mounting Some of the more common mounts: Rigid Cradle Belly band Stud C-frame Unit bearing 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 60
Cradle Mount 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 61
Rigid Mount Motor housing is welded to the base 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 62
Belly Band Mounting Motor slides into ring. Then band is tightened 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 63
Stud Mounts Studs are bolted to fan guard or housing. 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 64
Other Motor Mounting Styles C-frame Unit bearing 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 65
Motor Nameplate Nameplates contain essential information 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 66
Motor Nameplate explained 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 67
Motor Nameplate wiring diagram 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 68
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 2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 69
2005 Refrigeration Training Services - E2#1 Fan Motors v1.1 70