Electrical Connection; Frequency Converter Operation - Grundfos BM 4 Instrucciones De Instalación Y Funcionamiento

Fig. 13

6. Electrical connection

The electrical connection should be carried out by an authorised
electrician in accordance with local regulations and the diagrams
for the motor protection, starter and monitoring devices used.
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 booster modules must be connected to an exter-
nal mains switch.
BM: The electrical connections should be made in the terminal
box (figs. 14 and 15).
BMB: The motor cable and the supply cable should be connected
close to the flange, either by means of a terminal box (figs. 14
and 15) or a cable termination kit.
The submersible motors are wound for direct-on-line starting. Mo-
tors wound for star-delta starting are available on request. The
motor must be connected to an effective motor starter which must
protect the motor against damage from voltage drop, phase fail-
ure, overload and a locked rotor.
The ampere scale of the overload unit fitted to the starter should
be rated to cover the range from 0.8 to 1.2 times the motor full
load current.
The overload unit must trip out in less than 10 seconds with a
locked rotor, from cold.
If the overload characteristic does not meet this requirement, the
motor guarantee will be invalidated.
Manually operated motor starters should always be preferred and
must be used where variations in voltage are larger than ±10%.
Magnetic motor starters can be used where short variations in
voltage, if any, are smaller than ±10%.
If the contactor fails to trip, the magnetic motor starter does not
afford the motor any protection.
For automatic start/stop, remote control, etc., a separate contac-
tor should be used in conjunction with the manually operated mo-
tor starter. If there is a defect in the separate contactor, such as
burnt or welded contacts, the tripping effect of the overload unit is
not affected.
In electricity supply systems where undervoltage and variations in
phase symmetry may occur, a phase failure relay should also be
fitted.
The control circuit must always be made so that all modules are
stopped if one module fails.
Fig. 14
BM 4", BM 6", BM 8",
BMB 4", BMB 6" and BMB 8"
Direct-on-line
Black :U
Black
M
Red :V
Red
Yellow:W
Yellow
BK = Black
RD = Red
YE = Yellow
Fig. 15
BM 6", BM 8", BMB 6" and BMB 8"
Star-delta starting
W2 B2
S
U
P
V2 R2
P
L
U2 Y2
Y
W1 R1
F
O
R
V1 Y1
U1 B1
BK = Black
B=Black, R=Red, Y=Yellow
RD = Red
YE = Yellow

6.1 Frequency converter operation

GRUNDFOS Motors:
Three-phase GRUNDFOS MS motors can be connected to a fre-
quency converter.
Note: If a GRUNDFOS MS motor with a temperature transmitter
is connected to a frequency converter, a fuse incorporated in the
transmitter will melt and the transmitter will be inactive. The trans-
mitter cannot be reactivated. This means that the motor will oper-
ate like a motor without a temperature transmitter.
During frequency converter operation, it is not advisable to run
the motor at a frequency higher than the nominal frequency (50 or
60 Hz). In connection with pump operation, it is important never
to reduce the frequency (and consequently the speed) to such a
level that the necessary flow of cooling liquid past the motor is no
longer ensured.
To avoid damage to the pump part, it must be ensured that the
motor stops when the pump flow falls below 0.1 x nominal flow.
Depending on the frequency converter type, it may expose the
motor to detrimental voltage peaks.
The above disturbance can be abated by installing an RC filter
between the frequency converter and the motor.
Possible increased acoustic noise from the motor can be abated
by installing an LC filter which will also eliminate voltage peaks
from the frequency converter.
For further details, please contact your frequency converter sup-
plier or GRUNDFOS.
Other Motor Makes than GRUNDFOS:
Please contact GRUNDFOS or the motor manufacturer.
S
L1
U
P
L2
P
L
L3
Y
M
7