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3. Overspeed Adjustment (OS) - Over Frequency
Overspeed protection is provided by a frequency sensing network within the controller. The trip
point of the frequency network is adjustable via a rheostat located on the top of the controller at
the right hand side. Clockwise (CW) rotation increases the trip frequency and, thereby, raises the shutdown
speed.
CRANKING CONTROL
1. Overcrank Protection
This feature provides a preset second crank cycle. Failure of the engine to start by the end of the
crank period results in an "overcrank" shutdown and alarm indication.
2. Cranking Disconnect Adjustment (CDS Adjustment)
The cranking disconnect signal is obtained by a frequency network within the controller. The trip
point of the frequency network is not adjustable.
LOSS OF FREQUENCY
Internal protection against loss of frequency input to the cranking disconnect circuit is programmed in after the unit
has started normally. In the event the frequency goes to zero (engine runs out of fuel, frequency signal source fails,
etc.) the LOP shutdown circuit is bypassed and a 12-second wait period is initiated. If frequency returns within this
time period, LOP monitoring resumes and operation continues normally. If frequency has not returned at the end of
this time period, the engine oil pressure status is observed to determine whether the engine is actually running or
stopped. If the engine has stopped (i.e. air in fuel, etc.) the cranking cycle will begin in an effort to restart the engine.
If the engine has not stopped (loss of input signal, etc.) the unit is shut down with an "overcrank" indication and
alarm.
"Overcrank" indication can mean a loss of crank-disconnect signal during
the previous run period. Attempting to restart the engine with no crank-
disconnect can destroy the starter motor, which can cause serious
personal injury.
This is of particular note since the tendency is to pursue only cranking and start related faults. The cranking
disconnect signal source is a key component in this system and must be checked out thoroughly whenever an
"overcrank" shutdown occurs.
The controller does not provide protection against loss of signal during
startup. A shutdown with alarm, due to any of the above conditions, will
prevent any subsequent operation of the generator set. The run-stop-auto
selector switch on the control panel must be momentarily placed in the
"stop" position to reset these functions.
If a dead battery is suspected, remove controller fuse, Replace with new
battery and attempt starting. Damage to engine control may result from jump-
starting.