TM 10-4610-232-34
Table 2-1. Direct Support Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
HIGH PRESSURE PUMP.
WARNING
Electrical high voltage can cause serious injury or death. Some tests performed in
troubleshooting require power to be connected. Always take proper measures to ensure
personal safety.
1.
NOTE
Ensure that all circuit breakers are set before troubleshooting.
High pressure pump will not start. (Ref. Schematic diagram FO-1, sheet 6, schematic lines 632-637, control circuits; and
Schematic diagram FO-1, sheet 5, schematic lines 502-510, power circuits).
The high pressure pump motor uses a wye-delta method to reduce starting current and torque. It is considered a
closed transition system as it incorporates a resistor connected in series with each motor phase winding during the
switch from wye to delta. This eliminates opening the circuit and prevents transfer currents which may occur during an
“open” transition. The complete starter consists of: one 3-pole “1M“ contactor with overloads, one 3-pole “2M”
contactor, one 3-pole 1S contactor, one 3-pole “2S” transition contactor, one timer auxiliary contact block on the ”1M“
contactor, and three transition resistors. Pushing the start button energizes contactor ”1S“ which shorts together
motor leads 8T4, 8T5 and 8T6. When the “1S” contactor is energized it connects the motor windings in a wye
configuration and allows contactor ”1M“ to energize which connects the motor to the power source. The timer on
contactor ”1M“ starts timing as the motor accelerates in its wye configuration. After a time delay, as set on the ”1M“
timer, the timed contact closes and energizes the “2S” transition contactor, momentarily placing the transition
resistors in the circuit. The “2S” control contact opens, which drops the ”1S“ contactor out. The motor wye-point is
now opened with each end connected to the power source through contactor “2S” and the resistors. Reconnection to
delta is accomplished immediately when the “1S” control contact closes, which energizes the “2M” contactor. In
addition to the ”1S“ electrical interlock, which prevents the “2M” contactor from energizing, there is a mechanical
interlock between the “1 S’ and “2M” contractors as a further safeguard against energizing the two contractors at the
same time.
Step 1.
Step 2.
Step 3.
Step 4.
Shut down the ROWPU. Open the control panel. Check that the overload reset button MS8-1M (REF:
Interconnection diagram FO-2, Sheet 10) is in by pushing it.
(a) If the reset button is in, go to step 6.
(b) If the button is out and will not reset, replace the overload heaters on MS8-1M (para. 2-25).
(c) If the reset button is out, but resets when pushed, adjust the door rest assembly for MS8-1M. Refer to
para. 2-24 and then go to step 2.
Shut down the generator. Refer to electrical drawings in Appendix D and set multimeter to Ohms x 1000
scale. Check each lead, 8T1, 8T2 and 8T3 from the outlet side of MS8-1M to ground. Check each lead 8T4,
8T5 and 8T6 from the outlet side of MS8-2M (REF: Interconnection diagram FO-2, Sheet 10) to ground. The
reading should be infinity for each lead.
If the meter reading is zero, there is a short circuit. Refer to power circuit troubleshooting (malfunction 3).
Set the multimeter to Ohms x 1 scale and check for continuity between all pairs of motor leads: T1 (REF
Interconnection diagram FO-2, Sheet 10) and T4, T2 and T5, T3 and T6. Readings should be zero or near
zero.
If any reading is infinity, there is an open circuit. Refer to power circuit troubleshooting (malfunction 3).
Check each lead, 8T1, 8T2 and 8T3 from MS8-1M for damage, short, or tightness. Check each lead, 8T4, 8T5
and 8T6 from the outlet side of MS8-2M for damage and tightness.
Repair any loose or damaged wire (para. 2-20).
Change 1
2-69
