T M 1 0 - 4 6 1 0 - 2 3 2 - 1 2
Table 4-2. Unit Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
3. Raw water pump motor hums but won’t turn (Reference Schematic Diagram FO-1, Sheet 5, schematic lines 532-535).
step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Check generator voltage on all three phases. it must be 435-445 VAC on each phase.
Adjust to correct voltage.
If voltage is not correct on all three phases, refer to generator troubleshooting.
Check system air pressure and use an air manifold drain valve to lower it below 1400 psig (9653 kPa).
Turn the air compressor switch on and note if the air compressor runs. Alternately, turn on both
switches for the distribution pump and note if it runs.
If the 3-phase motors Iisted do not operate, notify direct support maintenance.
Check continuity, point-to-point, from P21E to J59A, P21F to J59B, P21G to J59C, and P21H to
J59D. Check each lead for shorts between phases and shorts to the ground wire. The reading should
be infinity for each check.
(a) Replace any cable or connector that shows open during continuity tests (para. 4-27).
(b) Replace any cable or connector that shows a short between phases or a short to ground para 4-27).
(c) Replace any loose or damaged wires in the external electrical and (para. 4-34).
(d) Replace any MOV’s in the external electrical panel that show physical damage or are shorted
to ground from the power terminal (para. 4-34).
Tag and disconnect motor leads (T1, T2, T3). Set multimeter to Ohms x 1000 scale and connect test
leads between each motor lead and the motor frame. Readings should be infinity for each step.
Replace pump/motor assembly if the meter reading is zero (para. 4-15).
Set multimeter to Ohms x 1 scale and check for continuity between all pairs of motor leads, T1 and
T2, T1 and T3, T2 and T3. Readings should be zero or near zero for each step.
Replace pump/motor assembly if reading is infinity (para. 4-15).
Check motor cable for continuity on each lead and for shorts between phases and ground. Replace
the cable if open or shorted (para. 4-15).
Notify direct support maintenance if the above checks have not found the problem.
4. Raw water pump won't start in system backwash (Reference Schematic Diagram FO-1, Sheet 5, schematic
lines 532-535).
Check that raw water pump starts in “SYSTEM NORMAL”.
(a) If the pump does not operate, refer to raw water pump won't operate ‘SYSTEM NORMAL”
troubleshooting (malfunction 1).
(b) Notify direct support maintenance.
5. Raw water pump circuit breaker opens whenever the pump is started, ROWPU shuts down when the raw water
pump is started (Reference Schematic Diagram FO-1, Sheet 5, schematic lines 532-535).
Check for short circuits.
(a) Shut down the ROWPU. Shutdown the generator.
(b) Refer to the electrical schematic Appx. I-1 and interconnect diagram Appx. I-2.
(c) Refer to raw water pump won't start troubleshooting, steps 5 thru 9 (malfunction 1).
(d) Notify direct support maintenance.
6. Raw water pump circuit breaker trips repeatedly, raw water ground fault trips repeatedly (Reference Schematic
Diagram FO-1, Sheet 5, schematic lines 532-537).
NOTE
This problem is hard to pin point directly as the two circuit breakers are electrically
tied together so that what affects one will usually trip the other even though each is
sensing different levels of short circuit. The direct-acting circuit breaker will only trip
NOTE Continued Next Page
4-66 Change 1
