Table 4-2. Unit Troubleshooting Guide (Continued)
TEST OR INSPECTION
when overcurrents exceed its setpoint, such as a direct bolted short circuit. By con-
trast, an arcing short circuit may amount to only a fraction of the direct-acting circuit
breaker setpoint and not cause it to trip. Arcing faults are typically caused by loose
connections, the presence of vermin, rodents, and insects in equipment, or insula-
tion deterioration as a result of mechanical damage, heat aging, or moisture, dust,
and other contaminants. Since the arcing type fault usually involves a flow of current
in the ground path, the ground fault circuit breaker monitors the ground circuit for cur-
rent flow. When it senses current in the ground circuit it will trip and also trip out the
pump circuit breaker. Under other circuit conditions-balanced, unbalanced, or sin-
gle phase load currents, or single or three phase short circuits not involving ground-
it will not trip even though the pump breaker does. For these reasons the following
troubleshooting steps are very general and success in isolating the problem relies on
the electrician to carefully inspect all cables, connectors, and connections for signs
of damage or moisture intrusion. In some cases only the substitution of known reli-
able components will identify the cause.
Shut down the ROWPU. Shut down the generator. Open the external electrical panel. Check all ca-
bles and connections from the control panel to the pump for tightness, physical damage, and evidence
of water, dirt, or arcing.. Open the motor connection box and check the connection inside it.
Repair an damage found.
Check the MOV's in the external electrical panel for physical damage or shorts to ground from the
Replace any faulty MOVS (para. 4-34).
Check for short circuits.
Refer to malfunction 1, steps 5 thru 9.
Use a pump from another unit and check it for operation.
(a) If the replacement pump runs okay, continue to check the faulty pump/motor for the problem.
(b) If the problem cannot be found, notify direct support maintenance.
7. Raw water pump circuit breaker will not reset, raw water pump ground fault will not reset (Reference Schematic
Diagram FO-1, Sheet 5, schematic lines 532-537).
Notify direct support maintenance.
CIRCUIT BREAKERS 440 VAC.
Circuit breaker will not reset.
This procedure does not apply to the distribution or raw water pump circuit breakers.
Refer to individual troubleshooting for those breakers.
Shut down ROWPU and reset the circuit breaker.
(a) If the breaker will not stay set, notify direct support maintenance.
(b) Refer to individual circuit troubleshooting for the breaker if it stays set with no power on the
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