Continuous Cranking
If desired, engine cranking can be delayed from zero to 30 seconds after initiating engine startup. When
continuous engine cranking is initiated, cranking is sustained for a user-adjustable period of one to 60
seconds. A crank disconnect limit setting (10 to 100% of nominal engine speed) selects the desired
engine speed above which cranking is terminated.
Cycle Cranking
If desired, engine cranking can be delayed from zero to 30 seconds after initiating engine startup. When
cycle engine cranking is initiated, five to 15 seconds of cranking is followed by an equal number of
seconds of rest. A maximum of seven cranking cycles (five cycles for NFPA compliant units) are allowed
by the DGC-500. A crank disconnect limit setting (10 to 100% of nominal engine speed) selects the
desired engine speed above which cranking is terminated.
Pre-Alarms
A pre-alarm is annunciated when a condition programmed to trigger a pre-alarm is met. When a pre-alarm
condition exists, the front panel Alarm indicator flashes on and off and the Horn output (if enabled through
BESTCOMS) alternates between an energized and de-energized state. The audible alarm is reset by
pressing the front panel Alarm Silence pushbutton.
Active pre-alarms for oil pressure, fuel level, coolant temperature, and battery voltage are displayed on
the main display of the LCD. The LCD annunciates an active pre-alarm by alternating between the current
parameter value and a blacked-out field for that value. All other pre-alarms are displayed in sequence
through the alternate mode display.
Each DGC-500 pre-alarm is described in the following paragraphs.
Low Oil Pressure
A low oil pressure pre-alarm occurs when the engine oil pressure decreases below the setpoint
programmed in BESTCOMS. The low oil pressure pre-alarm has a setting range of 3 to 150 psi or 20 to
1,035 kPa. A 10-second activation time delay prevents low oil pressure annunciation during engine
startup.
Low Fuel
A low fuel pre-alarm occurs when the fuel level decreases below the setpoint programmed in
BESTCOMS. The low fuel pre-alarm has a setting range of 10 to 100 percent.
High Coolant Temperature
A high coolant temperature pre-alarm occurs when the engine coolant temperature exceeds the setpoint
programmed in BESTCOMS. The high coolant temperature pre-alarm has a setting range of 100 to 280°F
or 38 to 138°C. A 60-second activation time delay prevents high coolant temperature annunciation during
system startup.
Low Coolant Temperature
A low coolant temperature pre-alarm occurs when the engine coolant temperature decreases below the
setpoint programmed in BESTCOMS. The low coolant temperature pre-alarm has a setting range of 50 to
100°F or 10 to 38°C.
Battery Overvoltage
A battery overvoltage pre-alarm occurs when the battery overvoltage pre-alarm function is enabled in
BESTCOMS and the battery voltage level exceeds 30 Vdc for 24 Vdc systems or 15 Vdc for 12 Vdc
systems.
Low Battery Voltage
A low battery voltage pre-alarm occurs when the battery voltage decreases below the low battery voltage
setpoint for the duration of the low battery voltage time delay setting. Both settings are made in
BESTCOMS. The low battery voltage setpoint has a setting range of 12 to 24 Vdc for 24 Vdc systems and
6 to 12 Vdc for 12 Vdc systems. The low battery voltage time delay has a setting range of 1 to 10
seconds.
Weak Battery Voltage
A weak battery voltage pre-alarm occurs when the battery voltage decreases below the weak battery
voltage setpoint for the duration of the weak battery voltage time delay setting. Both settings are made in
9355400990 Rev H DGC-500 Functional Description 3-9
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