Frequency Converter Operation; Operating Conditions Requirements; Startup; Flushing The Pipe System - Grundfos NBS Serie Instrucciones De Instalación Y Operación

6.3 Frequency converter operation

All three-phase motors can be connected to frequency converters.
Frequency converter operation will often expose the motor
insulation system to a heavier load causing the motor to be noisier
than usual due to eddy currents caused by voltage peaks.
A large motor driven by a frequency converter will be loaded with
bearing currents.
Check these operating conditions if the pump is driven by a
frequency converter:

Operating conditions Requirements

2-, 4- and 6-pole The motor must have an Aegis ground
motors, 100 hp (75 ring and the bearings must be electrically
kW) and above isolated. Contact Grundfos.
An output filter must be fitted between the
Noise-critical motor and the frequency converter. This
applications reduces the voltage peaks and thus the
noise.
Particularly noise-
A sinusoidal filter must be fitted.
critical applications
A cable must be fitted that meets the
Cable length specifications provided by the frequency
converter supplier.
The motor voltage must be suitable for
Supply voltage
frequency converter operation.
A sinusoidal filter must be fitted between t
he motor and the frequency converter.
High-peak voltages
The motor must have reinforced insulation
.
High voltage or current
A sinusoidal filter must be fitted and the
harmonics or harmonic
motor must have reinforced insulation.
sensitivity applications

7. Startup

Do not start the pump until it has been filled with liquid and
vented.

7.1 Flushing the pipe system

CAUTION
Biological hazard
Minor or moderate personal injury
‐
When pumping drinking water, the pump must be
flushed thoroughly with clean water before startup in
order to remove any foreign matters, such as
preservatives, test liquid, or grease.
• Before starting up the pump, thoroughly clean, flush and fill the
pipe system with clean water.
The warranty does not cover any damage caused by
flushing the pipe system by means of the pump.
The pump is not designed to pump liquids containing
solid particles such as pipe debris and welding slag.

7.2 Priming the product

7.2.1 Priming the product in closed systems or open systems
where the liquid level is above the pump inlet
1. Close the isolating valve in the outlet pipe and slowly open the
isolating valve in the inlet pipe. Both the pump and the inlet pipe
must be completely filled with liquid.
WARNING
Escaping liquid
Death or serious personal injury
‐
Pay attention to the orientation of the priming hole
to ensure that the escaping liquid does not cause
personal injury or damage to the motor or other
components.
‐
In hot-liquid installations, pay special attention to
the risk of personal injury caused by scalding hot
liquid.
‐
In cold-liquid installations, pay special attention to
the risk of personal injury caused by cold liquid.
2. Loosen the priming plug in order to vent the pump. Once liquid
runs out, tighten the priming plug.
7.2.2 Priming the product in inlet operation with check valve
The inlet pipe and the pump must be filled with liquid and vented
before the pump is started.
1. Close the isolating valve in the outlet pipe and slowly open the
isolating valve in the inlet pipe.
2. Remove the priming plug indicated by M.
3. Pour liquid through the hole until the inlet pipe and the pump are
completely filled with liquid.
4. Fit the priming plug indicated by M.
5. The inlet pipe may be filled and vented via the priming plug.
Alternatively, a priming device with funnel can be installed
before the pump.
M
E
Drain plug (E), priming and venting plug (M)
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