Dry-Running Protection - Grundfos CU 301 Mode D'emploi

5.7 Dry-running protection

The purpose of dry-running protection is to protect
a pump in case of insufficient water flow.
This built-in dry-running protection makes the
conventional external dry-running protection
device unnecessary.
No additional cables to the motor are required.
The dry-running protection is active after 30
seconds of operation.
The dry-running settings shown in section
9. Technical data are built into the pump and
automatically transmitted to CU 301. These
settings can be changed via Grundfos GO
Remote.
When air enters the pump together with water, the
pump power decreases, and pressure drops,
causing the motor to increase speed.
If the power consumption falls below the dry-
running setting for an accumulated time of 5
seconds, and the motor speed is within 1,000 rpm
of the maximum speed setting as defined in the
section 6.3.8 Maximum speed, CU 301 stops the
pump and signals a dry-running alarm.
When the motor stops, the dry-running indicator
light is permanently on. See fig.
indicator light, pos. A.
PSI
100
90
80
70
60
50
40
Dry-running indicator light
14
Possible cause
The pump performance
is too high compared to
the well yield.
The well screen is
blocked.
Restarting
After 5 minutes (factory setting), or the period set
in Grundfos GO Remote, the motor restarts
automatically. See section
restarting.
Related information
6.3.8 Maximum speed
6.3.5 Automatic restarting
6.3.7 Dry-running stop
9. Technical data
9. Technical data
Dry-running
A
Remedy
Replace the pump with
a smaller one.
Reduce the pump
performance using
Grundfos GO Remote.
See section
6.3.8 Maximum speed.
Well service is
required.
6.3.5 Automatic