Dry-Running Protection; Pressure/Level Switch - Grundfos Control MPC Installation And Operating Instructions Manual

8.7.45 Dry-running protection (4.4.1)

Fig. 95 Dry-running protection
Description
Dry-running protection is one of the most important monitoring
functions, as bearings and shaft seal may be damaged if the
pumps run dry. Grundfos thus always recommends dry-running
protection.
The function is based on monitoring of the inlet pressure or the
level in a possible tank or pit on the suction side.
Level switches, pressure switches or analog sensors signalling
water shortage at a set level can be used.
There are three different methods for detection of water shortage:
• Pressure switch on suction manifold or float switch/electrode
relay in the supply tank. See section
switch (4.4.1.1).
• Measurement of inlet pressure in the suction manifold by
means of an analog pressure transmitter. See section
8.7.47 Measurement, inlet pressure
• Measurement of level in the supply tank by means of an
analog level transmitter. See section
tank level (4.4.1.3).
Setting via control panel
• Settings > Monitoring functions > Dry-running protection >
Select method.
50
8.7.46 Pressure/level
(4.4.1.2).
8.7.48 Measurement,

8.7.46 Pressure/level switch (4.4.1.1)

Fig. 96 Pressure/level switch
Description
This function is primarily used in booster applications.
Dry-running protection can take place by means of a pressure
switch on the suction manifold or a level switch in a tank on the
suction side.
When the contact is open, the CU 352 will register water shortage
after a time delay of approx. five seconds. It is possible to set
whether the indication is to be just a warning or an alarm stopping
the pumps.
Restarting and resetting of alarms can be set to be automatic or
manual.
Setting range
• Selection of digital input for the function.
• Reaction in case of water shortage: Alarm + stop.
• Restarting: Manual / Auto.
Setting via control panel
• Settings > Monitoring functions > Dry-running protection >
Pressure/level switch > Go to setting of digital input.
Display Digital inputs (4.3.7) appears.
1. Set the input to dry-running protection.
2. .
3. Select:
• Warning / Alarm + stop.
• Manual / Auto.
Factory setting
The setting is done in the start-up wizard and depends on the
application.