Carrier DM-4 Power Pack Operation And Service Manual

Contents

1-52. Rear Starter Switch (RSS)This switch is active only when the (RCS) switch is inthe REAR position. Depressing this switch energizes thestarter circuit.b. Gauges and Indicators1. Oil Pressure Gauge (OP)The oil pressure gauge is used to monitor the engine oilpressure. Normal oil pressure is 40-60 psig with enginerunning at high speed and at operating temperature.2. Water Temperature Switch Gauge (WT)This gauge serves a dual function. It is used to monitorengine coolant temperature as well as serving as the switchfor the high temperature cut out. Normal engineoperating temperature is 180 to 210_F. The switchfunction should be set to close at 220-230_F.3. Hour Meter (HM)The unit Hour Meter will total unit operating hoursand is useful for scheduling maintenance intervals.4. Preheat Light (PHL)The preheat light will illuminate to indicate that theglow plug circuit has been energized. This function iscontrolled automatically by the Preheat controller. Thelight will go out when the glow plugs have been energizedlong enough to reach their required temperature forstarting the engine.5. A/C Stop Light (ASL)The AC stop light is activated by the oil pressure cutout switch. Its purpose is to indicate to the operator thatthe unit has stopped.1.9.3 Driver’s Control Panela. Switches1. Front A/C Switch (FAS)This switch allows the unit to be turned on or off fromthe driver’s panel. It is active only when the (RCS) switchon the unit panel is in the ‘‘front’’ position.2. Front Starter Switch (FSS)This switch is active only when the (RCS) switch is inthe FRONT position. Depressing this switch will energizethe engine starter circuit.3. Preheat Light (PHL)(Same as on main panel )4. A/C Stop Light (ASL)(Same as on Main Panel)1.10 ALTERNATORThe Power Pack is equipped with a 28 volt-140 amp.alternator . The alternator is connected in parallel with theair conditioning alternator driven by the main engine.Both of these alternators are used to independently powerthe air conditioning system.NOTE:The Power Pack engine controls and starter are12 volt and receive power from the bus 12 voltbatteries.CAUTIONObserve proper polarity when installing battery.Negative battery terminal MUST be grounded.Reverse polarity will destroy the rectifier diodesin the alternator. As a precautionary measure,disconnect positive battery terminal whencharging batteries. Connecting charger inreverse will destroy the rectifier diodes in thealternator.The alternator converts mechanical and magneticenergy to alternating current (A.C.) and voltage, by therotation of an electromagnetic field (rotor) inside athree-phase stator assembly. The alternating current andvoltage are changed to direct current and voltage, bypassing the A.C. energy through a three-phase, full waverectifier system. Six silicon rectifier diodes are used.1.10.1 Integral Voltage RegulatorThe regulator is an electronic transistorized device. Nomechanical contacts or relays are used to perform thevoltage regulation of the alternator system. The electroniccircuitry should never need adjustment and the solid stateactive elements used have proved reliable enough towarrant a sealed unit. The system is temperaturecompensated to permit a constant voltage rate at allconditions.The regulator is an electronic switching device. Itsenses the system voltage level and switches the voltageapplied to the field in order to maintain proper systemvoltage.1.11 Starter Lockout (SLO)The starter lockout (SLO) is an electronicallycontrolled relay that opens the starter motor circuit whena preset engine speed is reached. The signal source for thecontrol is the A.C. output of the unit alternator.Frequency directly proportional to engine speed ismonitored electronically within the control. When thespeed or frequency reaches the desired setting or setpointthe output relay within the control circuit is switched.Figure 1-7. Alternator Schematic Diagram