2020-2021 Purchasing Guide Volume 2

HVAC | Motors, Fan Blades & Wheels

MOTORWIRING

MOTOR REPLACEMENT

Replacing an old motor can be a fast and easy process if you can determine as much of the following information as possible.

TYPICAL WIRING DIAGRAM FOR SHADED-POLE MOTORS

1. Measure Motor Diameter Standard FASCI diameters are 3 1/3", 4 7/16", 5", and 5 5/8".

2. Identify the Motor Type Permanent-Split Capacitor (PSC) or Shaded-Pole. If the motor is a Permanent-Split Capacitor type, a capacitor will be present, either mounted on, or close to the motor (when in the unit) with wiring going from the motor to the capacitor terminals. The motor nameplate may list the capacitor rating. If the motor is a Shaded-Pole type, you will see one individual coil per pole and a shading band.

3. Identify the Motor Voltage This should be shown on the nameplate.

Standard wiring color codes as used by FASCO and most other manufacturers for Shaded-Pole motors. TYPICAL WIRING DIAGRAM FOR P.S.C. MOTORS

4. Identify the Motor Horsepower or Ampere Rating This information should be on the motor nameplate. 5. Identify Speed (RPM) This information should be on the motor nameplate. 6. Measure Shaft Length and Diameter Standard FASCI diameters are 1/4", 5/16", 3/8", 1/2", 5/8"—also type and length of flat on shaft. 7. Note Ventilation System Totally open, totally enclosed, or one end enclosed, etc.

Permanent-Split Capacitor motors have many different kinds of wiring arrangements. The standard wiring for FASCO and most other manufacturers is shown.

8. Note Motor Manufacturer’s Part Number

HP,AMPS, AND REPLACING MOTORS

VARIATIONS OF OHM’S LAW

When replacing a defective motor, use a replacement motor with the same horsepower. If the horsepower is unknown or below 1/4HP, match the amp rating. DO NOT use a replacement motor with a lower amp rating than the defective motor. You can use a replacement motor with up to 25% greater amp rating than the original motor. When matching amp ratings, also match capacitor sizes.

P (Watts) E (Volts) E (Volts) R (Ohms) =

E (Volts) P (Watts) I (Amps) I 2 (Amps) =

I (Amps)

R (Resistance)

=

=

P (Watts)

E (Volts) = I (Amps) x R (Ohms) =

NOTE: Some newer, more efficient motors may have lower amp ratings per horsepower.

I (Amps)

HORSEPOWERAMPERE TABLE The electrical ratings of many types of controls are often given in amperes. In general, these ampere ratings correspond to certain horsepower ratings. The ampere rating of all motors will not necessarily correspond to the horsepower rating shown in the table. Therefore, the control device in question must have a rating that is equal to (or greater than) the actual full load and locked rotor currents of the motor.

P (Watts) = I 2 (Amps) x R (Ohms) = I (Amps) x E (Volts)

CONVERSION TABLE KILLOWATTS – AMPERES – VOLTS

120 VOLTS A.C. 240 VOLTS A.C. FULL LOAD LOCKED ROTOR FULL LOAD LOCKED ROTOR

VOLTAGE (A.C. - SINGLE PHASE)

APPROXIMATE HORSEPOWER

KW (KILLOWATT)

120

208

240

277

AMPERES

1/10

3.0

18.0

1.5

9.0

.5

4.2 8.3

2.4 4.8 7.2 9.6

2.1 4.2 6.3 8.3

1.8 3.6 5.4 7.2 9.0

1/8

3.8

22.8

1.9

11.4

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

1/6

4.4

26.4

2.2

13.2

12.5 16.7 20.9 25.0 29.2 33.3 37.5 41.7

1/4

5.8

34.8

2.9

17.4

1/3

7.2

43.2

3.6

21.6

12.0 14.4 16.8 19.2 21.6 24.0

10.4 12.5 14.6 16.7 18.8 20.8

1/2

9.8

58.8

4.9

29.4

10.8 12.6 14.4 16.3 18.0

3/4

13.8

82.8

6.0

41.4

1

16.0

96.0

8.0

48.0

1-1/2

20.0

120.0

10.0

60.0

2

24.0

144.0

12.0

72.0

3

34.0

204.0

17.0

102.0

CHV026 - 12-12-14

522

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