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Description 1 EVC compared to EFC
The difference between the EVC and the EFC section valve is that the EFC section valve
has no pressure equalisation. The equalisation is adjusted by the pressure regulation valve
and is controlled by the computer.
Picture 9 shows the EVC section valve, the circled being the equalisation valve. This is the
clearest difference between the EVC and the EFC when looking at the section valves.
Picture 10 shows the EFC. Here there are no equalisation adjustment valves.
Picture 9 EVC with the equalization system
Picture 10 EFC without the equalization
Description 2 Min. duty cycle (or PWM, Pulse Width Modulation)
Figure 3 Pressure regulation valve
Figure 4 Duty circle for the pressure regulation
Menu: E 8.1.2
Minimum duty cycle (or PWM) is for adjusting the speed of the pressure regulation valve.
When the valve is trying to find the right flow, the speed of the valve must not be too high or
to low. If the speed is too high, the valve will be unsteady – if the speed is too low, the valve
not move as it can not overcome the friction.
Adjustment of the valve can therefore be as follows; find out where the valve is unsteady
and then reduce the min. duty cycle a bit.
The best setting for duty cycle is shown on Figure 4 in the circle. It shows the duty circle as
the setting should be. The flow, bottom line, is stable and the duty circle is circling around
the flow setting until it finds the right position.
