Checking Motor And Cable - Grundfos SP Series Installation And Operating Instructions Manual

11.1.4 Frequent starts and stops.
Frequent starts and stops.
Cause
The differencebetween the start
and stop pressures is too small.
The water level electrodes or
level switches in the reservoir
have not been installed
correctly.
The non-return valve is leaking
or stuck half-open.
The precharge pressure of the
tank is too low.
The tank is too small.
The diaphragm of the tank is
defective.
Remedy
Increase the difference. The stop
pressure must not exceed the
operating pressure of the
pressure tank, and the start
pressure must be high enough to
ensure sufficient water supply.
Adjust the intervals of the
electrodes or level switches to
ensure suitable time between the
cutting-in and cutting-out of the
pump. See installation and
operating instructions for the
electrodes or level switches. If the
intervals between stop and start
cannot be changed via the
automatics, the pump
performance may be reduced by
throttling the outlet valve.
Pull out the pump and clean or
replace the valve.
Adjust the precharge pressure of
the tank in accordance with its
installation and operating
instructions.
Increase the capacity of the tank
by replacing it or supplementing it
with an additional tank.
Check the diaphragm tank.

12. Checking motor and cable

DANGER
Electric shock
Death or serious personal injury
‐
Switch off the power supply before starting any work
on the product.
‐
Make sure that the power supply cannot be accidental-
ly switched on.
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