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39. YCDO
value for tight closing, bottom
If the setpoint is less than the YCDO value, the actuator will actuator the valve to 0%. This function
can prevent premature wear on the valve seat due to too little valve opening.
40. YCUP
value for tight closing, top
With this function, the valve can be driven into the valve seat with the maximum actuator force of
the actuator (piezo valves in the positioner are permanently controlled).
The tight closing function can be activated for one end layer or for both end positions. This
function can be activated if the setpoint of the setting value is less than the value of the "YCDO"
parameter, or greater than the value with the parameter "YCUP".
Note
1.
The value of YCDO must always be set lower than the value of YCUP.
2.
The sealing function has a fixed hysteresis of 1%.
41. YNRM
Manipulated variable standardization
Use the "YA" and "YE" parameters to limit the setting size. This limitation creates two different
scales for the display and for the position feedback via the current output: MPOS or FLOW. (see
Fig. 8-2).
The MPOS scaling indicates the mechanical position between 0 to 100% - between the upper and
lower stop of the initialization. The position is not affected by the "YA" or "YE" parameters. The
"YA" and "YE" parameters are displayed at MPOS scale.
The FLOW scale is the standardization from 0 to 100% over the range between the parameters
"YA" and "YE". In this range, the setpoint "W
" is always
from 0 to 100%. This results in a flow-
proportional display and position feedback "AO". The flow-proportional display and position
feedback "AO" is also obtained when using valve characteristics.
To calculate the control difference, the setpoint is also displayed in the display at the appropriate
scale.
The following is the example of a 40 mm linear actuator to illustrate the dependence of the stroke
on standardization, as well as on the parameters "YA" and "YE".
Fig.8-1 YNRM = MPOS or YNRM = FLOW; Default: YA = 0% and YE = 100%