DKG-255 User Manual Firmware V-1.0
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The unit is designed to operate from a DC supply of 12 or 24 volts, which is usually the engine starter
battery. The battery is connected to terminals C and D. A reverse polarity protection is provided.
The unit should be supplied with a speed signal at the inputs E and F. The signal comes usually from a
magnetic pickup unit mounted in close proximity of the engine ring gear. The frequency of the speed
signal is proportional to the engine rpm.
Alternatively, the unit accepts the alternator voltage as the speed signal. The alternator voltage can be up
to 300VAC.
The minimum acceptable amplitude of the speed signal is
1.5 VAC-RMS
. The acceptable frequency
range is 4
0 Hz to 8’000 Hz. If MPU unit is connected, the use of a shielded cable is recommended. The
shield should be grounded at one end only.
The actuator output is energized only when a speed signal is present. The unit will shut-off the actuator if
an adequate signal is not connected to the inputs.
The engine speed is adjusted from
P_01 Nominal Speed
parameter. This will allow a precise adjustment
of the desired engine rpm.
The stability of the speed is adjusted with the
P_13 Global Gain
parameter. This parameter will modify
the dynamic response of the unit to speed changes and allow adaptation to different type of engines.
The GAIN parameter adjusts the reaction rate of the unit to speed changes. The unit will become more
sensitive as the parameter is increased. This will allow a faster return to the nominal speed when a load
change occurs. Do not forget that excess gain will cause instability.
The
STARTING RPM FUEL
P_09
,
RUNNING RPM FUEL P_10
and
SPEED RAMP
P_11
parameters
will prevent the actuator from opening completely and minimize engine exhaust smoke.
The
OVERSPEED
parameters adjusts the speed alarm threshold. When the engine overspeeds, this will
activate the overspeed alarm and the related error led will turn on.
During cranking, the speed signal will be below the
P_07 Running rpm
, which causes the actuator to
open as defined by
P_09 Starting RPM Fuel
. When the engine has fired and the speed reaches
P_07
Running rpm,
the unit will initiate speed ramping until the engine reaches the nominal speed. Then the
actuator will be supplied only with the amount of current necessary to maintain the nominal speed.
A sudden load increase on the engine shaft will result to a speed drop. This will cause the actuator to
open more in order to reach the nominal speed. A sudden load decrease will cause a speed increase.
This will cause the actuator to shut-off gradually until reaching again the nominal speed.
The actuator output is a switchmode circuit which supplies nearly the battery voltage when turned on.
This allows the unit to deliver high output currents with high efficiency and minimum self-heating. The
switching frequency is well above the natural oscillation frequency of the actuator moving parts and is not
detectable.
The unit offers the automatic learning feature for adjusting PID coefficients.
In order to activate the auto PID setup:
After starting the engine, enter programming parameters and select
P_22 Auto PID Setup
parameter.
Press
button to set 1 and then press
button to confirm. The unit will start to modify the engine
speed in order to calculate optimum PID coefficients. If operation is completed successfully, OK message
will be written on display. An error message will be displayed if auto PID setup fails.
Auto PID setup operation must be performed with no load.
8.1. AUTO PID SETUP
8. OPERATION OF THE UNIT
