Protective Functions; Dry-Running Protection - Grundfos Hydro Multi-E Series Installation And Operating Instructions Manual

15. Protective functions

It is important that any protective function, for example
dry-running protection or external start/stop that is detected via a
digital input, is connected to and configured on all the pumps with
an outlet-pressure sensor.
If an additional sensor is used, for example the limit-exceeded
function or setpoint influence, this sensor must also be connected
to all pumps with an outlet-pressure sensor. Alternatively, an
additional sensor per pump with an outlet-pressure sensor can be
installed.

15.1 Dry-running protection

Hydro Multi-E must be protected against dry running.
Types of dry-running protection:
• A pressure switch or an inlet pressure sensor is factory-fitted
to the inlet manifold. See section
15.1.3 Inlet pressure sensor.
• A level switch is fitted in a water tank (optional). See section
15.1.2 Level switch.
15.1.1 Pressure switch
The Hydro Multi-E can be fitted with an adjustable pressure
switch as dry-running protection. The pressure switch is fitted to
the inlet manifold.
If the inlet pressure is below the lower switching
point, the system cannot start.
If the pressure switch stops the system during
operation due to the inlet pressure being too low, the
inlet pressure must increase to a pressure that is
higher than the setting of the upper switching point
before the system can restart.
If necessary, adjust the lower switching point by turning screw A,
and adjust the upper switching point to a value higher than the
lower switching point by turning screw B. See fig. 51.
Do not set the lower switching point to a value below
the minimum inlet pressure. See section
27.5 Minimum inlet
A B
Fig. 51 Adjustment of switching points
Pos. Description
A Low pressure SP
B High pressure SP
15.1.1 Pressure switch and
pressure.
15.1.2 Level switch
If there is no inlet pressure, the system can be optionally fitted
with a level switch, either from factory or after delivery. The level
switch must be connected to terminal 3 and 10 in all pumps, then
it can monitor the water level in a tank connected to the inlet
manifold. See section Advanced functional module (FM
Furthermore, the digital input must be configured with Grundfos
GO Remote to detect dry running.
The system starts up automatically if it has been stopped due to
dry running. It can be changed to manual restart with Grundfos
GO Remote.
Pump
1
L S
Fig. 52 Level switch connected to each pump
15.1.3 Inlet pressure sensor
Multi-E systems with inlet sensors have Limit Exceed
(Low Limit) configured for dry-running protection
The Hydro Multi-E system can be fitted with one or two inlet
pressure sensors, either from factory or after delivery. The sensor
can monitor the pressure in the inlet manifold and must be
connected to one of the analog inputs. See section
functional module (FM 300).
The analog input is configured with Grundfos GO Remote or via
the HMI300 graphical control interface. Configure one of the
"Limit exceeded" functions to detect dry-running.
From factory, the system is set to start automatically if it has been
stopped due to dry-running. It can be changed to manual restart
with Grundfos GO Remote or via the HMI 300 graphical control
interface.
300).
Pump
2
3: GND (frame)
3
10: Digital input
10
3: GND (frame)
3
10: Digital input
10
Advanced
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