Maintenance – Single-Phase Motors & Controls
Ohmmeter Tests
QD, Solid State Control Box (Power Off)
A. START CAPACITOR AND RUN CAPACITOR IF APPLICABLE (CRC)
1.Meter Setting: R x 1,000.
2.Connections: Capacitor terminals.
3.Correct meter reading: Pointer should swing toward zero, then back to infi nity.
B.Q.D. (BLUE) RELAY
Step 1. Triac Test
1.Meter setting: R x 1,000.
2.Connections: Cap and B terminal.
3.Correct meter reading: Infi nity for all models.
Step 2. Coil Test
1.Meter Setting: R x 1.
2.Connections: L1 and B.
3.Correct meter reading: Zero ohms for all models.
C. POTENTIAL (VOLTAGE) RELAY
Step 1. Coil Test
1.Meter setting: R x 1,000.
2.Connections: #2 & #5.
3.Correct meter readings:
For 115 Volt Boxes:
For 230 Volt Boxes:
Step 2. Contact Test
1.Meter setting: R x 1.
2.Connections: #1 & #2.
3.Correct meter reading: Zero for all models.
Ohmmeter Tests
Integral Horsepower Control Box (Power Off)
A. OVERLOADS (Push Reset Buttons to make sure contacts are closed.)
1.Meter Setting: R x 1.
2.Connections: Overload terminals.
3.Correct meter reading: Less than 0.5 ohms.
B.CAPACITOR (Disconnect leads from one side of each capacitor before checking.)
1.Meter Setting: R x 1,000.
2.Connections: Capacitor terminals.
3.Correct meter reading: Pointer should swing toward zero, then drift back to infinity, except for capacitors with resistors which will drift back to 15,000 ohms.
C.POTENTIAL (VOLTAGE) RELAY Step 1. Coil Test
1.Meter setting: R x 1,000.
2.Connections: #2 & #5.
3.Correct meter readings:
Step 2. Contact Test
1.Meter Setting: R x 1.
2.Connections: #1 & #2.
3.Correct meter reading: Zero ohms for all models.
D.CONTACTOR Step 1. Coil
1.Meter setting: R x 100
2.Connections: Coil terminals
3.Correct meter reading:
Step 2. Contacts
1.Meter Setting: R X 1
2.Connections: L1 & T1 or L2 & T2
3.Manually close contacts
4.Correct meter reading: Zero ohms
CAUTION: The tests in this manual for components such as capacitors, relays, and QD switches should be regarded as indicative and not as conclusive. For example, a capacitor may test good (not open, not shorted) but may have lost some of its capacitance and may no longer be able to perform its function.
To verify proper operation of QD switches or relays, refer to operational test procedure described on page 46, Section
47