TM 10-4610-232-34Table 2-1. Direct Support Troubleshooting Guide (Continued)MALFUNCTIONTEST OR INSPECTIONCORRECTIVE ACTIONHIGH PRESSURE PUMP.WARNINGElectrical high voltage can cause serious injury or death. Some tests performed introubleshooting require power to be connected. Always take proper measures to ensurepersonal safety.1.NOTEEnsure 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; andSchematic 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 aclosed transition system as it incorporates a resistor connected in series with each motor phase winding during theswitch 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 togethermotor leads 8T4, 8T5 and 8T6. When the “1S” contactor is energized it connects the motor windings in a wyeconfiguration and allows contactor ”1M“ to energize which connects the motor to the power source. The timer oncontactor ”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 transitionresistors in the circuit. The “2S” control contact opens, which drops the ”1S“ contactor out. The motor wye-point isnow opened with each end connected to the power source through contactor “2S” and the resistors. Reconnection todelta is accomplished immediately when the “1S” control contact closes, which energizes the “2M” contactor. Inaddition to the ”1S“ electrical interlock, which prevents the “2M” contactor from energizing, there is a mechanicalinterlock between the “1 S’ and “2M” contractors as a further safeguard against energizing the two contractors at thesame 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 topara. 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 1000scale. 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. Thereading 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 (REFInterconnection diagram FO-2, Sheet 10) and T4, T2 and T5, T3 and T6. Readings should be zero or nearzero.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, 8T5and 8T6 from the outlet side of MS8-2M for damage and tightness.Repair any loose or damaged wire (para. 2-20).Change 12-69
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