Frequency Converter Operation; Start-Up; Priming; Checking The Direction Of Rotation - Grundfos CM Instrucciones De Instalación Y Funcionamiento

8.3 Frequency converter operation

All three-phase motors 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.
ML 71 and ML 80-based motors (see motor
nameplate) have no phase insulation* and must
therefore be protected against voltage peaks
higher than 650 V (peak value) between the
supply terminals.
*ML 71 and ML 80-based motors with phase insulation are
available on request.
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
supplier or Grundfos.

9. Start-up

Do not start the pump until it has been primed.

9.1 Priming

Warning
The system may be under pressure, and the
escaping liquid may be scalding hot. Care must
therefore be taken to ensure that the liquid does
not cause personal injury or damage to other
components.
1. Close the isolating valve on the discharge side of the pump.
2. Open the isolating valve in the suction pipe completely before
starting the pump.
3. Remove the priming plug. See fig. 11.
4. Fill the pump housing and the suction pipe completely with
liquid until a steady stream of liquid runs out of the priming
hole.
5. Fit and tighten the priming plug.
6. Slowly open the discharge isolating valve while the pump is
running. This ensures venting and pressure build-up during
start-up.
The discharge valve must be opened immediately
after start-up of the pump. Otherwise the
temperature of the pumped liquid may become
too high and cause material damage.
Fig. 11 Plugs in the pump sleeve
If the pump is not building up pressure, it may be
necessary to repeat steps 1. to 6.
Priming plug
Drain plug

9.2 Checking the direction of rotation

The description below applies to three-phase
motors only.
The motor fan cover has an installation indicator. See fig. 12.
Based on the motor cooling air, it indicates the direction of
rotation of the motor.
Before the motor is started for the first time or if the position of the
indicator has been changed, the indicator function should be
checked, for instance by moving the indicator field with a finger.
To determine whether the direction of rotation is correct or wrong,
compare the indication with the table below.
Indicator field
Black
White/reflecting
*To reverse the direction of rotation, switch off the power supply
and interchange any two of the incoming supply wires.
Indicator field
Fig. 12 Installation indicator
The indicator can be placed in various positions on the motor, but
it must not be placed between the cooling fins close to the screws
holding the fan cover.
The correct direction of rotation is also shown by arrows on the
motor fan cover.

10. Maintenance

Warning
Before starting work on the pump, make sure that
the power supply has been switched off and that
it cannot be accidentally switched on.
The internal pump parts are maintenance-free. It is important to
keep the motor clean in order to ensure adequate cooling of the
motor. If the pump is installed in dusty environments, it must be
cleaned and checked regularly. Take the enclosure class of the
motor into account when cleaning.
The motor has maintenance-free, greased-for-life bearings.

10.1 Frost protection

Pumps which are not being used during periods of frost should be
drained to avoid damage.
Remove the priming and drain plugs. See fig. 11.
Do not refit the plugs until the pump is taken into operation again.
Before start-up after a period of inactivity, the
pump and the suction pipe should be completely
filled with liquid. See section 9.1 Priming.

10.2 Cleaning

Prior to a long period of inactivity, the pump must be flushed with
clean water to prevent corrosion and deposits in the pump.
Direction of rotation
Correct
Wrong*
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