Xylem HYDROVAR HV 4.150 / 4.185 / 4.220 - Manual (Page 98)

98
Examples:
Booster unit
Problem: no stop of the HYDROVAR
Parts to check measure
• existing demand
• non return valve is not closed
• pre charge pressure in the pressure tank
• incorrect setting
of WINDOW and
RAMPHYSTERESIS
• shut down ramp too slow
• suction line too long
• check pipes and valves
• change non return valve
• adjust according the diagram
• set WINDOW [0310] (ca.10%) and
HYSTERESIS [0315] (80-50%)
• set RAMP 2 [0220] to 4...13 sec.
• the MINIMUM FREQUENCY [0250] should be
activated for pressure increase at 0 demand
Control on constant flow
Problem: control fluctuations
Parts to check measure
control characteristics are set too low
enlarge r WINDOW [0310] and set
HYSTERESIS [0315] to 99% to control with
RAMP 3 and 4
Circulating pump
Problem: oscillation of the motor speed
Parts to check measure
control settings too fast
• increase RAMP 3 [0225] and 4 [0230]:
100...200sec
• WINDOW [0310] (ca.20%) and
HYSTERESIS [0315] (ca.99%)
Problem: ACTUAL VALUE can't be hold
Parts to check measure
HYSTERESIS is set too big HYSTERESIS [0315]: 90-99%
General
Problem: pressure fluctuations, analogue signal not constant
Solution: • check cables and connection of the screen
• check earth connection of the transmitter cable
• use screened cables