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3.2 Insulating the pump housing
If the pump is installed in a cabinet or fitted with
insulation shells, the inside air temperature must
be evaluated. If you expect constant ambient air
temperatures higher than 130 °F (54 °C), please
contact Grundfos.
3.3 Electrical installation
•
The motor is protected by the electronics in
the control box and requires no external
motor protection.
•
UL-approved ALPHA1 26-99/ALPHA2 26-99
circulators are equipped with a conduit box
for easy installation of the power cable.
Inrush current
The inrush current is the charge current to the
electrolytic capacitor in the power supply to the
electronics. The maximum current amplitude
depends on the power supply and the complete
wiring from the distributor transformer to the
pump. The pump is internally controlled by a
small variable frequency drive (VFD) running on
a DC voltage. Therefore, the supply voltage is
rectified to a DC voltage before it reaches the
VFD.
The load of electronically commutated motors
(ECM) behaves as a capacitive load and not as
a motor load as in a standard pump. When the
power supply is switched on, the capacitor will
behave as a short circuit (as it is "empty", i.e. it
has not been charged). Therefore, the current is
only limited by the sum of the resistance in the
NTC thermistor and the resistance in the coil of
the EMC filter.
If the power supply is switched on when the
supply voltage is at its highest level, the inrush
current can become very high for a very short
period of time. After this period of time, the
current will drop to the rated current.
When the power supply to the pump is switched
on and off via an external relay, it must be
ensured that the contact material of the relay is
able to handle higher inrush currents. We
recommend to use special inrush relays with
silver-tin-oxide (AgSnO) contacts.
Leakage current
The pump mains filter causes a leakage current
to ground during operation.
High-voltage test
The pump incorporates filter components that
are connected to ground. The voltage level and
the number of tests should be as low as
possible, in order to grant the longest lifetime in
the market. Additional standard high-voltage
tests of the complete pump including filter must
be avoided to eliminate the risk of filter damage.
Do not insulate the control box,
especially the heat sink, in order to
allow cooling by the surrounding air.
Do not cover the pump head with
diffusion-tight, cold-water insulation.
Keep the drain holes located in the
stator housing free.
DANGER
Electric shock
Death or serious personal injury
- All electrical work must be carried
out by a qualified electrician in
accordance with the latest edition
of the National Electric Code and
state, local codes and regulations.
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 accidentally switched on.
DANGER
Electric shock
Death or serious personal injury
- Do not use the pump in swimming
pool or marine areas.
WARNING
Electric shock
Death or serious personal injury
- This pump is supplied with a
grounding conductor. To reduce the
risk of electric shock, be certain
that it is connected only to a
properly grounded, grounding-type
receptacle in accordance with the
National Electric Code and any
state, local governing codes and
regulations.
The pump must not be used with an
external speed control which varies
the supply voltage, for example
phase-cut or pulse-cascade control.
Check that the supply voltage and
frequency correspond to the values
stated on the pump.
