11
3.2 Dry-running protection
The purpose of the dry-running protection is to pro-
tect the pump in case of insufficient water flow.
The dry-running protection makes the conventional
dry-running protection unnecessary.
No additional cables to the motor are required. The
dry-running settings shown in section 8. Technical
data, are built into the pump and automatically trans-
mitted to the CU 301. These settings can be
changed via the R100.
When air enters the pump together with water, the
pump power decreases, and pressure drops, caus-
ing the motor to increase speed. If the power con-
sumption falls below the dry run setting for an accu-
mulated time of 5 seconds, and the motor speed is
within 1,000 rpm of the maximum speed setting as
defined in the section 5.3.6, the CU 301 stops the
pump and declares a dry-running alarm.
When the motor is stopped, the dry-running indicator
light is permanently on, see fig. 13, pos. A.
Fig. 13 Dry-running indicator light
Restarting
After 5 minutes (factory setting) or the period set by
means of the R100, display 5.3.4 Automatic restart,
the motor will restart automatically.
TM02 4170 1606
Possible cause Remedy
The pump performance
is too high compared to
the well yield.
Replace the pump with
a smaller one.
Reduce pump perfor-
mance using the R100,
display 5.3.6 Maximum
speed.
Well screen is blocked. Well service is required.
PSI
100
90
80
70
60
50
40
A
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