Xylem HYDROVAR HV 4.150 / 4.185 / 4.220 - Manual (Page 88)

88
Example for using the Offset function:
Constant pressure system with required value of 5 bar.
Additionally a flow sensor is connected to the Offset input.
Parameter [907] - Offset Range = 160 (max. range of flow sensor = 16m³/h)
System requirement 1:
5 bar constant pressure while the flow rate is between 5m³/h and 12m³/h.
Below the 5 m³/h the pressure should be decreased with the limitation to have max. 2,5 bar
at a flow rate of 2m³/h.
Settings:
Parameter [0910] - Level 1 = 50 = 5m³/h (first limit where the offset function is active)
Parameter [0912] - Offset X1 = 20 = 2m³/h (fixed point according the requirements)
Parameter [0913] - Offset Y1 = 2,5 = 2,5bar (max. allowed pressure at this flow rate)
System requirement 2:
5 bar constant pressure while the flow rate is between 5m³/h and 12m³/h.
Above the 12 m³/h the pressure should be increased with the limitation to have max. 6,0
bar at max. flow rate of 16m³/h.
Settings:
Parameter [915] - Level 2 = 120 = 12m³/h (second limit where the offset function is active)
Parameter [917] - Offset X2 = 160 = 16m³/h (fixed point according the requirements)
Parameter [918] - Offset Y2 = 6 = 6bar (required pressure at this flow rate)
Required Value - Sollwertverlauf (Offseteinfluss)
0
2
4
6
8
10
12
14
16
0 20 40 60 80 100 120 140 160
Offse t
R
e
q
u
ir
e
d
/
S
o
ll
w
e
rt
2m³/h
OFFSET Y1
OFFSET X1
OFFSET X2
OFFSET Y2
Level 1
Level 2
5m³/h 12m³/h