10
10.4 Emergency operation
All functions of the Hydro Multi-S are controlled by an electronic
circuit board inside the control cabinet. If the circuit board should
fail, it is possible to avoid system stops. For three-phase booster
sets, it is possible to bypass the circuit board and operate the
booster set by using the pressure switches only.
To establish emergency operation, proceed as follows:
1. Switch off the electricity supply, and open the control cabinet.
2. Remove the control connector from its original position, see
fig. 5, pos. A, and insert the connector in the emergency
position, see fig. 5, pos. B.
3. Close the control cabinet, and switch on the electricity supply.
Fig. 5
Electronic circuit board
11. Functions
The Hydro Multi-S offers the following features:
•
Automatic cascade control of pumps by means of two or three
pressure switches.
•
Automatic pump changeover at any start/stop cycle.
•
If a pump is in fault status, it is automatically taken out of
operation.
•
Automatic resetting of dry-running fault status.
•
Manual resetting of tripped-overload status.
•
Pump and system protection:
– Short-circuit protection by means of fuses.
– Motor protection by means of a thermal overload relay.
– Dry-running protection by means of an additional pressure
switch or level switch.
– Start-up delay between two pumps: Prevents simultaneous
start-up of more than one pump.
12. Settings
12.1 Setting the pressure switches
Each booster set is factory-tested, and the pressure switches are
adjusted to ensure optimum performance.
During installation and commissioning, it might be necessary to
adjust the settings to optimise operation in the actual installation.
See fig. 6.
Fig. 6
Pressure switch
12.1.1 Setting the cut-out pressure
To set the cut-out pressure (p
cut-out
), proceed as follows:
1. Turn the P1 screw clockwise to increase the cut-out pressure
and counter-clockwise to decrease the cut-out pressure. See
fig. 6.
2. Set the cut-out pressures with a difference of 0.3 to 0.5 bar
respectively (cascade step) on each pressure switch.
3. Start the pump, and check by reading the pressure gauge
whether the desired cut-out pressure has been obtained for
each pressure switch.
12.1.2 Setting the differential pressure
To set the differential pressure (p
diff.
), turn the P2 screw clockwise
to increase the differential pressure and counter-clockwise to
decrease the differential pressure. The cut-out pressure remains
unchanged. See fig. 6.
The differential pressure must be set to the same value on all
pressure switches.
12.1.3 Cut-in pressure
The cut-in pressure (p
cut-in
) is automatically set when the
differential pressure is set.
p
cut-in =
p
cut-out –
p
diff.
To check whether the cut-in pressure is as desired, proceed as
follows:
1. Start the pump, and check by reading the pressure gauge
whether the desired cut-out and cut-in pressures have been
obtained.
2. Repeat the above setting procedures until the right cut-in and
cut-out pressures have been obtained.
Warning
The terminals and the cables connected before
the mains switch will remain powered even if
the switch is in off position.
Caution
Emergency operation should only be used in
case of emergency and only for short periods
of time.
A defective circuit board should always be
replaced by a new one. Contact Grundfos for
a new circuit board.
T
M
03
97
25
44
07
A
B
Warning
The cut-out pressure must under no
circumstances exceed the maximum operating
pressure of the pump and tank.
TM
03
97
91
44
07
Note
Reducing the differential pressure to a minimum
can reduce pressure variations in the system.
