Grundfos SQ User Manual

16
9.1 Megging
Megging of an installation incorporating SQ/SQE
pumps is not allowed, as the built-in electronics may
be damaged, see fig. 12.
Fig. 12
4. Frequent starts
and stops.
a) The differential of the pressure
switch between the start and stop
pressures is too small.
Increase the differential. However, the stop
pressure must not exceed the operating
pressure of the pressure tank, and the start
pressure should be high enough to ensure
sufficient water supply.
b) The water level electrodes or level
switches in the reservoir have not
been installed correctly.
Adjust the intervals of the electrodes/level
switches to ensure suitable time between
the cutting-in and cutting-out of the pump.
See installation and operating instructions
for the automatic devices used. If the
intervals between stop/start cannot be
changed via the automatics, the pump
capacity may be reduced by throttling the
discharge valve.
c) The non-return valve is leaking or
stuck half-open.
Pull out the pump and clean/replace the
non-return valve.
d) The supply voltage is unstable. Check the electricity supply.
e) The motor temperature gets too
high.
Check the water temperature.
Fault Cause Remedy
TM02 0689 5000
CC
U
U
U
PE
N
L
C
C

Grundfos SQ Specifications

General

Motor	Permanent magnet motor
Material	Stainless steel
Protection class	IP68
Frequency	50/60 Hz
Application	Irrigation, Pressure boosting
Pumped liquid	Water
Power Supply	Single-phase or Three-phase
Operating Temperature	0 - 40 °C