Frequency Converter Operation; Starting Up The Product; Operating The Product; Product Introduction - Grundfos MTH series Montage- Und Betriebsanleitung

2.4.5 Frequency converter operation

Motors supplied by Grundfos
All three-phase motors supplied by Grundfos can be
connected to a frequency converter.
Depending on the frequency converter type, this may
cause increased acoustic noise from the motor.
Furthermore, it may cause the motor to be exposed
to detrimental voltage peaks.
Grundfos motors, types MG 71 and MG 80
as well as MG 90 (1.5 kW, 2-pole), for
supply voltages up to and including 440 V
(see motor nameplate), must be protected
against voltage peaks higher than 650 V
(peak value) between the supply terminals.
We recommend to protect all other motors against
voltage peaks higher than 850 V.
The above disturbances, that is both increased
acoustic noise and detrimental voltage peaks, can be
eliminated by fitting an LC filter between the
frequency converter and the motor.
For further information, please contact the frequency
converter supplier or Grundfos.

3. Starting up the product

Before starting the pump, make sure:
• that all pipe connections are tight.
• that the pump body is partly filled with liquid
(partly submerged).
• that the strainer is not blocked by impurities.
Start the pump as follows:
1. Close the isolating valve on the outlet side of the
pump.
2. See the correct direction of rotation of the pump
on the motor fan cover. When seen from the top,
the pump must rotate counterclockwise.
3. Start the pump and check the direction of
rotation.
4. Slowly open the outlet valve until it is completely
open.
The pump has now been vented and is ready for
operation.

3.1 Operating the product

CAUTION
Fire and explosion
Minor or moderate personal injury
- Do not use the pump for flammable,
combustible or explosive liquids.
CAUTION
Hot liquid
Minor or moderate personal injury
- Do not run the pump against a closed
valve for more than approximately 5
minutes.
The pump is not allowed to run against a
closed outlet valve for more than
approximately 5 minutes as this will cause
an increase in temperature and formation
of steam in the pump which may cause
damage to the pump.

4. Product introduction

4.1 Applications

Grundfos pumps, type MTH, are multistage
centrifugal pumps designed for pumping liquids for
machine tools, condensate transfer, liquid transfer in
industrial washing machines and similar
applications.
The pumps are designed for pumping liquids with a
density and viscosity corresponding to those of
water. The pumped liquid must not contain abrasive
particles or fibres.
When pumping liquids with a density or viscosity
higher than that of water, the motor size must be
taken into consideration.

4.2 Identification

4.2.1 Type designation

The standard range consists of pumps with several
impeller and chamber combinations. On request,
other pump lengths can be supplied by fitting empty
intermediate chambers in combination with standard
impellers and chambers.
The type key on the pump nameplate indicates the
number of chambers and impellers fitted to the
pump.
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