Grundfos PT - Electrical connection; Start-up; Shaft seal run-in; Adjustment

English (GB)
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5. Electrical connection
The electrical connection should be carried out by an
authorised electrician in accordance with local
regulations.
Single-phase motors incorporate a thermal switch
and require no additional motor protection.
Three-phase motors must be connected to an
external mains switch and a motor-protective circuit
breaker.
6. Start-up
6.1 Shaft seal run-in
The seal faces are lubricated by the pumped liquid,
meaning that there may be a certain amount of
leakage from the shaft seal.
When the pump is started up for the first time, or
when a new shaft seal is installed, a certain run-in
period is required before the leakage is reduced to
an acceptable level. The time required for this
depends on the operating conditions, i.e. every time
the operating conditions change, a new run-in period
will be started.
Under normal conditions, the leaking liquid will
evaporate. As a result, no leakage will be detected.
7. Adjustment
If the pressure settings are not suitable for the
application, adjust according to the following.
7.1 Calculating the cut-in and cut-out
pressures
The cut-in pressure is the sum of these variables:
• required minimum pressure at the highest
tapping point
• head
from the pump to the highest tapping point
• pressure loss in pipes.
Recommended cut-out pressure:
cut-in pressure + 0.8 - 1.5 bar.
7.2 Adjusting the precharge pressure
When the pump cut-in pressure has been
determined, the required precharge pressure of the
diaphragm tank can be calculated. The precharge
pressure must be adjusted to 90 % of the cut-in
pressure.
See the installation and operating instructions for the
diaphragm tank.
Warning
Check that the supply voltage and
frequency match the voltage and
frequency on the nameplate.
Warning
Before making any connections in the unit,
make sure that the power supply has been
switched off and that it cannot be
accidentally switched on.
The unit must be connected to an external
mains switch with a contact gap of at least
3 mm in all poles.
As a precaution, the unit must be
connected to a socket with earth
connection.
We recommend to fit the permanent
installation with an earth leakage circuit
breaker (ELCB) with a tripping current
< 30 mA.
Caution
Do not start the pump until it has been
filled with liquid.
Note
The default setting can be found in the
quick guide.
Note
The cut-out pressure must not exceed the
maximum discharge pressure of the pump.
Caution
When adjusting/reading the precharge
pressure, make sure that there is no water
pressure on the diaphragm tank from the
pipework.
Note
If the pressure switch setting is changed,
the precharge pressure must be adjusted
too.