Liquid Temperatures/Cooling; Electrical Connection; General - Grundfos SQ Installation And Operating Instructions Manual

Fig. 2
Not allowed
If the pump is to be installed horizontally, e.g. in a
tank, and there is a risk that the pump might be cov-
ered by mud, it must be fitted in a flow sleeve.
For installation depths, see section 5.8.2 .

3.3 Liquid temperatures/cooling

Figure 3 shows an SQ/SQE pump installed in a bore-
hole. The pump is operating.
Figure 3 illustrates the following:
• Borehole diameter.
• Pump diameter.
• Temperature of pumped liquid.
• Flow past the motor to the pump suction strainer.
Fig. 3
Liquid
temperature
6
To ensure sufficient cooling of the motor, it is impor-
tant to observe the values for maximum liquid tem-
peratures and the minimum flow velocity of the
pumped liquid past the motor, see the following
table:
Allowed
To ensure free convection, the borehole diameter
must be at least 2" larger than the diameter of the
submersible motor:
• Pump diameter including cable guard is 74 mm.
• 2" ~ 50 mm.
The borehole diameter must be at least 124 mm to
enable free convection.
Note: The borehole diameter must be at least 76 mm
(approx. 3").
The motor must not have free convection if there is a
risk that the motor will be covered in sediments.
The motor should always be installed above the well
screen. If a flow sleeve is used, the pump may be
installed freely in the borehole.
Note: Do not let the pump run against a closed dis-
charge pipe for more than 5 minutes. When the dis-
charge pipe is closed, there is no cooling flow and
there is a risk of overtemperature in motor and
pump.
If the actual temperature of the pumped liquid
exceeds the specified value or the operating condi-
tions otherwise fall outside the specified conditions,
the pump may stop. Please contact GRUNDFOS.
Borehole

4. Electrical connection

diameter

4.1 General

The electrical connection should be carried out by an
Pump
authorized electrician in accordance with local regu-
diameter
lations.
The supply voltage, rated maximum current and
power factor (PF) appear from the motor nameplate.
The required voltage for GRUNDFOS submersible
motors, measured at the motor terminals, is
–10%/+6% of the nominal voltage during continuous
operation (including variation in the supply voltage
and losses in cables).
If the pump is connected to an electric installation
where an earth-leakage circuit breaker (ELCB) is
used as an additional protection, this circuit breaker
must trip out when earth fault currents with DC con-
tent (pulsating DC) occur.
Flow velocity
past the motor liquid temperature
0.0 m/s
30°C (86°F)
(free convection)
Min. 0.15 m/s 40°C (105°F)
Before starting work on the pump, make
sure that the electricity supply has been
switched off and that it cannot be acciden-
tally switched on.
The pump must be earthed.
The pump must be connected to an exter-
nal mains switch.
Maximum