Woodward 2301D, Инструкция по установке и эксплуатации, Страница: 88 / 130

2301D/2301D-EC Digital Control Manual 26247
80 Woodward
Maximum Fuel Function
The Maximum Fuel Function is a software-adjustable maximum fuel limit on the
fuel demand. It is used to set a maximum position of the actuator. This is
generally used to prevent engine overloading or other situations where the
maximum fuel delivered to the engine should be limited. The function can be
disabled by adjusting the Max Fuel Limit to 100%. The maximum fuel limiter is
disabled in systems configured for reverse acting actuator.
Start Limit Function
The Start Limit Function provides a limit to the fuel demand which prevents
overfuel conditions during starting of the engine (Figure 6-2). During start-up,
when engine speed exceeds the MPU fail speed, the Start Limit Function is
momentarily triggered to immediately limit the fuel demand to a software-
adjustable start fuel limit. The start ramp begins increasing the fuel demand at a
software-adjustable rate shortly after the start fuel limit is triggered. The rate can
be set at zero to eliminate the ramp function. When engine speed reaches 95%
of the speed reference, and the PID is in control of the fuel demand for 1 second,
the Start Limit Function will immediately increase to a maximum value of 100%.
When engine speed decreases below 5% of rated speed from a shutdown, the
Start Fuel Limit Function is disabled and re-armed for trigger during the next
start. The start fuel limit function also works on reverse-acting systems. The
function can be disabled by adjusting the Start Fuel Limit to a value of 100.
Figure 6-2. Start Limit Function
Torque Limiter
The Torque Limit Curve (TLC) sets the limit fuel demand based on the engine
speed input. This fuel limit prevents overfueling which limits torque for up to three
speed break points. The input break points units are in rpm. The fuel limits are in
percent fuel demand. Fuel demand is generally set slightly above the fuel
required to carry the allowable load for each specific break point rpm. A setting
that is too low can degrade transient load performance. The torque limiter is set
in Service menu L**Fuel Limiters1/2**.