80209C_MHW_850-1650-1850_01-2020_ENG_pag. 220
5.14.2. Valve control modes
In valve control, every request for a maneuver greater than
minimum impulse is sent to the actuator via the relays with
function V.OPEN / V.CLOS.
In the case of floating valve each action updates the
assumed position of the virtual potentiometer calculated on
the basis of declared actuator travel time. This mode always
provides an assumed valve position, which is compared with
the controller’s position request.
After reaching an assumed end position (fully open or
fully closed determined by the virtual potentiometer), the
controller supplies an additional command in the same
direction, thereby ensuring that the real end position is
reached.
With feedback valve, the actual position is acquired via the
auxiliary analog input of the controller, which reparameterizes
the value as a forcentage (0.0 - 100.0%), compares it to the
required position, then sends the appropriate command to
the valve.
Calibration is required to store the minimum and maximum
positions of the potentiometer.
The actuators are normally protected against an OPEN
command in fully open position or a CLOSE command in
fully closed position.
There are two setpoint approach modes:
• Non-impulsive behavior
Set TIM.HI = 0 and TIM.OF=0 for non-impulsive behavior:
every request greater than TIM.LO is continually sent to
the actuator via the V.OPEN / V.CLOS outputs.
The shortest pulse time is settable in TIM.ON as
forcentage of the “actuator time”, it is recommended to
set TIM.ON=TIM.LO
With power equal to 100.0% or to 0.0%, the
corresponding output remains on.
• Impulsive behavior
Set TIM.HI ≠ 0 and TIM.OF=0 for impulsive behavior.
every request greater than TIM.LO is sent to the actuator
via the V.OPEN / V.CLOS outputs with impulses having a
duration of TIM.ON.
TIM.HI defines the deviation within which the movement
becomes pulsing.
With power equal to 100.0% or to 0.0%, the
corresponding output remains on.
With TIM.OF ≠ 0, every request greater than TIM.LO is
sent to the actuator via the V.OPEN / V.CLOS outputs
with impulses having a duration of TIM.ON and TIM.OF.
In the case of floating valve, with power ≤ 10.0%, or ≥
90.0%, the impulses are independent of TIM.LO.
With power equal to 100.0% or to 0.0%, the
corresponding output remains in modulation.
t0 t1 t2
TIM.HI TIM.LO TIM.LO TIM.LO
Valve
control
Time
TIM.HI ≠ 0 e TIM.OF = 0
Deviation
Impulsive
behavior
threshold
TIM.ON TIM.ON
TIM.OF TIM.OF TIM.OF
TIM.ON TIM.ON
Valve
control
Deviation
Time
TIM.OF ≠ 0
Impulsive behavior
With the controllers in manual, setting parameter KEY.MO =
On allows direct control of the valve open and close com-
mands with the
and only when HOME is displayed.
When the controller goes to automatic mode, with a floating
valve, the assumed position is calculated starting from the
set manual power.
To Next Page
Loading...
Need help?
General
