Table 2-1. Direct Support Troubleshooting Guide (Continued)
TEST OR INSPECTION
HIGH PRESSURE PUMP.
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
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
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
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).