Frequency Converter Operation; Start-Up; Maintenance; Lubrication - Grundfos CRK Series Installation And Operating Instructions Manual

Before removing the terminal box cover and
before any removal/dismantling of the pump,
make sure that the electricity supply has been
switched off.
The pump must be connected to an external
mains switch with a minimum contact gap of
0.125" [3.2mm] in all poles.
The operating voltage and frequency are marked on the pump
nameplate. Please make sure that the motor is suitable for the
electricity supply on which it will be used.
Single-phase Grundfos motors incorporate a thermal switch and
require no additional motor protection.
Three-phase motors must be connected to a motor starter.
The terminal box can be turned to four positions, in 90° steps, see
fig. 14:
1. If necessary, remove the coupling guards.
Do not remove the coupling.
2. Remove the bolts securing the motor to the pump.
3. Turn the motor to the required position.
4. Replace and tighten the bolts.
5. Replace the coupling guards.
The electrical connection should be carried out as shown in the
diagram inside the terminal box cover.
0˚
270˚
180˚
Fig. 14 Terminal box positions

8.1 Frequency converter operation

8.1.1 Motors supplied by Grundfos:
All three-phase motors supplied by Grundfos can be connected to
a frequency converter.
Dependent 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.
Note: Grundfos motors types ML 71 and 80 as well as ML 90 (2.0
Hp [1.5 kW], 2-pole), all for supply voltages up to and including
480 V or 440 V for ML (see motor nameplate), must be protected
against voltage peaks higher than 650 V (peak value) between
the supply terminals. It is recommended to protect all other
motors against voltage peaks higher than 850 V.
The above disturbances, i.e. 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 or
motor supplier.
8.1.2 Other motor makes than those supplied by Grundfos:
Please contact the motor manufacturer.

9. Start-up

Pay attention to the direction of the vent hole (if
equipped) and take care to ensure that the
escaping water does not cause injury to persons
or damage to the motor or other components.
9.0.1 Before starting the pump, make sure:
•
•
•
9.0.2 Start the pump as follows:
1. Close the isolating valve on the discharge side of the pump.
2. If the pump is fitted with a vent valve, this valve must be
3. See the correct direction of rotation of the pump on the motor
4. Start the pump and check the direction of rotation.
5. Open the discharge isolating valve a little.
6. If the pump is fitted with a vent valve, this valve must be
90˚
7. Completely open the discharge isolating valve.
The pump has now been vented and is ready for operation.
Note: The pump is not allowed to run against a closed discharge
valve for more than approx. 5 minutes as this will cause an
increase in temperature/formation of steam in the pump which
may cause damage to the pump.

10. Maintenance

Pumps installed in accordance with these instructions require
very little maintenance.

10.1 Lubrication

The mechanical shaft seal is self-adjusting and has wear-
resistant seal rings which are lubricated and cooled by the
pumped liquid.
The pump bearings are also lubricated by the pumped liquid.
Most motor ball bearings are grease packed and sealed for life.
No further lubrication is necessary.
If the pump is to be drained for a long period of inactivity, remove
one of the coupling guards to inject a few drops of silicone oil on
the shaft between the pump head and the coupling. This will
prevent the shaft seal faces from sticking.
10.1.1 Motor bearings:
Motors which are not fitted with grease nipples are maintenance-
free.
Motors fitted with grease nipples should be lubricated with a high-
temperature lithium-based grease, see the motor nameplate.

10.2 Filters

Chip trays, filters, etc. should be cleaned at regular intervals to
ensure a correct flow of liquid.
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.
opened, see fig. 15.
Fig. 15
fan cover or on the coupling guard. When seen from the top,
the pump should rotate counter-clockwise.
closed when a steady stream of liquid runs out of it.
Before starting work on the pump, make sure
that all power supplies to the pump have been
switched off and that they cannot be accidentally
switched on.
Vent valve
7