Burkert Type 8624 - Manual (Page 37)

8624-2 Standard - 35
english
6.6.9 VALV - adaptation of controller output signal
Î In the menu item VALV, the
actual value is displayed
Display of pulse-duty factor of valve
➔ With this key, the pulse-duty factor of the proportional valve is
increased, i.e. it opens up to a max. of 100%.
➔ 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
pressure, 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