Winco DPG-2145-001 - Manual (Page 20)

Manual 36526F DPG-21XX-00X Digital Controllers
Woodward 12
derive a good starting point for the speed filter value for a given engine application.
Round the result to the nearest integer. The maximum value allowed is 24.
[(No._of_flywheel_teeth) / (No._of_engine_cylinders)] * 0.75 = speed_filter_value
For installations using ignition pulses to sense engine speed
It is recommended that the Speed Filter be at least equal to the number of ignition
pulses per one revolution of the engine. A good starting point would be 2 times the
number of ignition pulses per one revolution of the engine.
[(pulses_per_rev) * (2)] = speed_filter_value
3.13 Idle Hold Time (optional)
The idle hold time specifies how long, after starting, the engine is to stay at the idle
speed before finishing the ramp to the target speed. The time value has a resolution of
one-tenth of a second.
During the startup sequence, the controller increases the engine speed from the
engine's crank speed to the active target speed at the STARTUP RATE specified. If the
IDLE HOLD TIME is nonzero, the initial target speed will be the IDLE SPEED. After the
IDLE HOLD TIME expires, the controller then uses the ACCEL RATE to ramp the
engine to the selected set speed (REMOTE SPEED POT or SET SPEED A). The
startup sequence is complete once the engine speed reaches the selected set speed.
3.14 Accel Rate (optional)
This rate specifies how fast the controller should increase the engine’s speed when a
new, higher target speed is made active. The parameter value is specified in Hertz per
second based on the following formula.
[(higher_speed_in_Hertz) – (lower_speed_in_Hertz)] / (ramp_time_in_seconds) =
accel_rate_value
For example, suppose Set Speed A is 3300 Hertz and Set Speed B is at 3960 Hertz.
The controller is currently controlling the engine at 3300 Hertz (Set Speed A), when Set
Speed B becomes the active target speed. It is desired that the new speed of 3960 be
reached in precisely 2 seconds. The following formula determines the value needed by
Accel Rate to increase the engine speed from Set Speed A to Set Speed B in 2
seconds.
[(Set Speed B) – (Set Speed A)] / (N seconds) = accel_rate_value in Hertz per second
[3960 – 3300] / 2 = 330 Hertz per second
3.15 Decel Rate (optional)
The Decel Rate specifies how fast the controller should decrease the engine’s speed
when a new lower target speed is made active. The parameter value is specified in
Hertz per second based on the following formula.
[(higher_speed_in_Hertz) – (lower_speed_in_Hertz)] / (ramp_time_in_seconds) =
decel_rate_value
For example, suppose Set Speed A is 4170 Hertz and Set Speed B is 3475 Hertz. The
controller is currently controlling the engine at 4170 Hertz (Set Speed A), when Set
Speed B becomes the active target speed. It is desired that the new speed of 3475 be
reached in precisely 1.5 seconds. The following formula determines the value needed