Burkert Type 8625 - Manual (Page 35)

8625-2 Standard - 33
english
6.6.8 VALV - adaptation of controller output signal
In the menu item VALV, the
actual value is displayed.
Display of pulse-duty factor of valve
Î With this key, the pulse-duty factor of the
proportional valve is increased, i.e. it opens
up to a max. of 100%.
Î With this key, the pulse-duty factor of the
proportional valve is decreased.
As soon as the controller output is changed by pressing
the
or key, the display changes automatically to
controller output. On releasing the key, the actual value
is again displayed.
In this menu item, the controller output can be adapted optimally to the working
range of the actuator currently covered in the application. The proportional valve
is driven by a pulse width modulated (PWM) signal from the controller. Opening of
the valve does not begin at a pulse-duty factor of 0 of the PWM signal, but on
account of the spring force opposing the magnetic force, only at a certain value.
This start of opening depends upon the nominal diameter of the valve, the
admission temperature, and because of temperature dependence of the coil
resistance, also on the coil temperature. The function of the controller can be
optimized by having its output range begin not at 0, but at the start of opening in
the current application.
Display of actual value
Fig.: Adaptation of controller output signal