A common Capacitor Start Pool Motor has three sets of windings: two sets of main windings which are engaged while the motor is running and a third Capacitor winding that provides extra torque in the motor during its initial startup. This guide shows you how to measure the resistance in these coils to determine if this is the cause of a failed motor. MAKE SURE THE POWER IS OFF before you take these measurements.
THE ISSUE - Your pool pump motor won't rotate under power but the shaft turns freely. What is the problem? A motor has several electrical components that might fail: start capacitor; overload protector; power terminal; loose wires; and motor windings. . This guide shows how to measure the motor windings to eliminate them from further consideration.
TURN OFF POWER - Make sure to TURN OFF POWER to your pump before opening up the electrical end of the pump. You will probably be working with 240V so be careful. If you are not familiar with electricity, have an electrician help you. Turn off the power at the circuit breaker to the pump for maximum protection.
SHORT OUT CAPACITOR - Pool Pump Capacitors store an electrical charge that can shock you even when the power is off. Before removing the capacitor, discharge this energy by placing an insulated screwdriver across the leads of the capacitor. CAUTION: Capacitors have been know to explode when shorted out. For your protection wear eye protection and place a cloth over the capacitor before shorting it out.
WIRING DIAGRAM - This picture shows the location of the winding circuits that you will be measuring. There are three sets of windings: the main windings are split into two sets, shown in the green box; the auxiliary start capacitor winding is shown in the red box. The start capacitor winding provides extra torque during the initial startup of the motor to help prime the pool system. In general, you will be taking 4 readings. You will be comparing the resistance readings of one set of main windings against the other, Then you will be comparing the resistance readings of one set of main windings plus the start-up windings to the other set of main windings with the start-up windings. The measurement points are identified by blue circles. They include: the "L2" power terminal; the "A" power terminal; the yellow wire attached to terminal 3 on the Overload Protector, and the end of the red lead going to the switch. For these measurements the red lead to the switch must be detached to simulate and open switch.
COMPARE READINGS - Compare the reading taken above for the upper main widnings and the lower main windings. They should be the same. If no, you will probably need to replace the motor.
COMPARE READINGS - Compare the reading taken above for the upper main widnings plus start windings, and the lower main windings plus start windings. They should be the same. If not, you will probably need to replace the motor.