Burkert 8630 Instructions De Service page 126

Charact
Selection of the transmission characteristic curve between the input signal and the stroke (correction characteristic
curve)
User specific characteristic curve (Characteristic)
Factory setting:
With this function you select a transmission characteristic curve in relation to the position set value (position setpoint) and to the
valve stroke to correct the flow rate respectively the operating characteristic curve.
The flow characteristic k
v
valve and is expressed by the k
s of the valve spindle. It is determined by the shape of the
valve body. There are normally two types of flow
characteristic curves: linear and equal percentage.
In the case of linear characteristic curves equal changes
in stroke ds are assigned to equal k
(dk = n ds).
v lin
In the case of an equal percentage characteristic curve,
a change in stroke ds corresponds to an equal
percentage change in the k
(dk /k = n
v v equalperc
The operating curve Q = f
(s)
and the stroke s. This curve is also affected by the properties of the pipelines, pumps and consumers. It therefore has a form,
which deviates from the flow characteristic curve.
Specific requirements are usually laid down for the operating characteristic curve (e.g. linearity) in the case of correcting tasks for
closed loop control systems. Therefore it is sometimes necessary for this reason to correct the pattern of the operating curve in a
suitable manner. A transmission element, which implements various characteristic curves that can be used to correct the
operating curve, is provided in the Top Control Continuous for this purpose.
The equipercentile curves 1:25, 1:33, 1:50, 25:1, 33:1 and 50:1 and a linear characteristic may be set. Furthermore, it is possible
to programme any characteristic via reference points or have it calibrated automatically.
Top Control Continuous
LIN
= f characterises the flow of a
(s)
value relative to the stroke
v
value changes dk
v v
value
v
ds).
represents the relationship between the rate of flow Q which flows through a valve fitted in the system
linear characteristic curve
equal percentage characteristic curve,
1 : 25
equal percentage characteristic curve,
1 : 33
equal percentage characteristic curve,
1 : 50
inverse equal percentage,
25 : 1
inverse equal percentage,
33 : 1
inverse equal percentage,
50 : 1
user specific freely programmable
characteristic curve based on
temporary restart points
Standard
valve stroke [%]
Fig. 6.7: Corrective characteristic curves
Standard
position setpoint [%]
125