Burkert Type 8793 - Manual (Page 108)

108
Auxiliary functions
26.2.1. CHARACT – Select the transfer characteristic between
input signal (position set-point value) and stroke
Characteristic (customer-specific characteristic)
Use this auxiliary function to select a transfer characteristic with reference to set-point value (nominal position, CMD)
and valve stroke ( POS) for correction of the flow-rate or operating characteristic.
Factory setting: linear
Each auxiliary function, which is to be set, must be incorporated initially into the main menu (MAIN).
See Chapter “26.1. Activating and deactivating auxiliary functions”, page 105.
CHARACT linear
GP 1:25
GP 1:33
GP 1:50
GP 25:1
GP 33:1
GP 50:1
FREE
Linear characteristic
Equal percentage characteristic 1:25
Equal percentage characteristic 1:33
Equal percentage characteristic 1:50
Inversely equal percentage characteristic 25:1
Inversely equal percentage characteristic 33:1
Inversely equal percentage characteristic 50:1
*. .User-defined characteristic, freely program-
mable via nodes
SELEC ENTER
EXIT
* EInput the nodes see chapter “26.2.1.1. Inputting the freely programmable characteristic”
Figure 52: Operating structure CHARACT
The flow characteristic k
V
= f(s) indicates the flow-rate of a valve, expressed by the k
V
value depending on the stroke
s of the actuator spindle. It is specified by the design of the valve seat and the seat seal. In general two types of flow
characteristics are implemented, the linear and the equal percentage.
In the case of linear characteristics identical k
V
value changes k
V
are assigned to identical stroke changes ds.
(dk
V
= n
lin
⋅ ds).
In the case of an equal percentage characteristic an equal percentage change of the k
V
value corresponds to a
stroke change ds.
(dk
V
/k
V
= n
equalper
⋅ ds).
The operating characteristic Q = f(s) specifies the correlation between the volumetric flow Q in the installed valve
and the stroke s. This characteristic has the properties of the pipelines, pumps and consumers. It therefore exhibits
a form which differs from the flow characteristic.
english
Type 8792, 8793