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

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 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 v1.2

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

_ + 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 + © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

_ + 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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 A Phase Shift is Needed 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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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

Examples of Shaded-Pole Motors © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 v1.2

Rotation toward the Shaded Pole © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Shaded-Pole Motor Wiring COMMON LINE BLACK LINE GREEN GROUND © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 v1.2

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 v1.2

Shaded-pole C-frame Motor © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 To Reverse Rotation Turn Stator Around ` ` © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 Turn fan blade around Rotation is now reversed ` © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 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 v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Start & Run Winding Resistances START WINDING COM V/  V AC DC S Ω Ω Ω R © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Windings of a split phase motor Run Windings Start Windings © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 v1.2

PSC Motor with run capacitor Low Starting Torque Low to Medium Cost Medium Efficiency © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Split Phase Motor + Run Cap = PSC Motor RUN WINDING START WINDING S R Run Capacitor © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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. © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

PSC Motor Wiring Diagram COMMON LINE BLACK LINE BROWN W/ WHITE BROWN GREEN GROUND CAPACITOR © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 Motor Speeds The synchronous 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 v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 4 Run Windings 1 2 1 4 Start Windings Four Pole Motor 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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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: 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 v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Single-Speed PSC Motor RUN WINDING START WINDING S R Run Capacitor © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Single-Speed PSC Motor RUN WINDING START WINDING R C S Run Capacitor © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 Multi-speed PSC Motor High Speed RH C Medium Speed RM START WINDING RUN WINDING S R Low Speed RL © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

3-Speed PSC Motor Wiring Diagram COMMON LINE BLACK-HIGH BLACK LINE LINE BLUE-MED RED-LOW BROWN W/ WHITE BROWN GREEN GROUND © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 v1.2

PSC 3-speed Motor Leads for changing motor rotation Run Capacitor Leads Common Wire Low Speed (red) Medium Speed (blue) High Speed (black) © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 Three Phase Motors High starting torque High efficiency Medium to high cost © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 Three Phase Motors © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 v1.2

3Ø Motor – Wye Connections L1 208 V 208 V T1 T3 T2 L2 208 V L3 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

3Ø Motor – Delta Connections 240 V 240 V T3 T2 L2 240 V L3 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Describing Common Motors Motor descriptions include the following information: Type Enclosure Mounting © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Common Motor Types Shaded Pole Split Phase Permanant Split Capacitor Three Phase © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 Motor Enclosure Types Open Dripproof Totally enclosed Totally enclosed fan cooled © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Open Enclosure Types Totally Open Open Dripproof Note: Prevents direct entry of moisture Clean and Mostly Dry Locations Clean and Dry Locations © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 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 v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 Cradle Mount © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Rigid Mount Motor housing is welded to the base © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Belly Band Mounting Motor slides into ring. Then band is tightened © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Stud Mounts Studs are bolted to fan guard or housing. © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

Other Motor Mounting Styles Unit bearing C-frame © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2 Motor Nameplate Nameplates contain essential information © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 © 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2

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 v1.2

© 2005 Refrigeration Training Services - E2#1 Fan Motors v1.2