Section 5
ENGINE DC CONTROL SYSTEM
ENGINE CONTROL CIRCUIT BOARD
GENERAL:
The ENGINE CONTROL circuit board is responsible for cranking, startup, running, and shutdown opera- tions. The board interconnects with other components of the DC control system to turn them on and off at the proper times. It is powered by fused 12 VDC power from the unit battery.
CIRCUIT BOARD CONNECTIONS:
The circuit board mounts two,
OVERSPEED SHUTDOWN POTENTIOMETER:
The overspeed shutdown potentiometer is used to set the frequency at which the board will initiate a engine shutdown. Proper setting of the potentiometer is criti- cal to the correct operation of the generator.
ADJUSTMENT PROCEDURE:
The overspeed shutdown potentiometer MUST be adjusted on replacement circuit boards.
If not replacing a board, start at STEP 6.
1.Remove 14 amp fuse (F1) from control panel.
2.Disconnect all wires from circuit board terminals.
The following chart shows the associated wires and the function(s) of each terminal and wire.
TERMINAL | WIRE | FUNCTION |
1 | 15 | Power supply (12VDC) for the circuit board |
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| and DC control system. |
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2 | 0 | Common Ground |
3 | 17 | To Start Stop Switch and remote connector. |
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| When grounded by setting |
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| Switch to "START", engine will crank. |
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4 | 18 | To |
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| When grounded by setting |
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| Switch to "STOP", engine shuts down. |
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5 | 44 | Frequency signal for overspeed |
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| shutdown/starter disengage. |
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6 | 22 | Frequency signal for overspeed |
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| shutdown/starter disengage. |
7 | 56 | Delivers 12 VDC to Starter Contactor (SC) |
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| while cranking only. |
8 | __ | Not Used |
9 | 14 | Engine run circuit. Delivers 12 VDC during |
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| cranking and running. |
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| Connected to Fuel Pump, Fuel Solenoid, |
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| Hourmeter, and field boost circuit. |
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10 | 14 | Engine run circuit. Delivers 12 VDC during |
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| cranking and running. |
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| Connected to Fuel Pump, Fuel Solenoid, |
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| Hourmeter, and field boost circuit. |
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11 | 14 | Engine run circuit. Delivers 12 VDC during |
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| cranking and running. |
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| Connected to Fuel Pump, Fuel Solenoid, |
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| Hourmeter, and field boost circuit. |
1285 Fault shutdown circuit. When grounded by High Water Temperature or Low Oil Pressure switch, engine will shut down.
LED FUNCTIONS:
Green LED will be illuminated when Wire 14 is ener- gized during cranking and running.
Red LED will be illuminated when Wire 56 is ener- gized during cranking only.
3.Remove old circuit board and install new circuit board.
4.Connect all wires to proper circuit board terminals. Follow elec- trical schematic if needed.
5.Reinstall 14 amp (F1) fuse into control panel.
6.Turn the overspeed shutdown potentiometer slowly counter- clockwise until it stops. DO NOT FORCE.
Note: If immediate shutdown occurs when the engine starts and the START/STOP switch is released, reverse overspeed shutdown pot set- ting, turn pot clockwise and proceed. In Step 10 and Step 11, turn the overspeed shutdown pot counterclockwise.
7.Connect an accurate AC frequency meter across the genera- tor's AC output leads.
8.Start the generator, let it stabilize and warm up.
9.Use the injection throttle lever to SLOWLY increase engine speed until the frequency meter reads 64 hertz.
10.Hold the throttle at 64 hertz and SLOWLY turn the overspeed shutdown potentiometer clockwise until engine shutdown occurs.
11.Turn the overspeed shutdown potentiometer clockwise an additional 1/8 turn. The overspeed setting is now correct.
BATTERY
RECOMMENDED BATTERY:
When anticipated ambient temperatures will be con- sistently above 32° F. (0° C.), use a 12 VDC automo- tive type storage battery rated 70
The QUIETPACT 75D generator is rated at about 160 DC Amps of cranking current to operate the starter and glow plugs.
BATTERY CABLES:
Use of battery cables that are too long or too small in diameter will result in excessive voltage drop. For best cold weather starting, voltage drop between the
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