Frequency Converter Operation; Motor Protection; Setting Of Motor-Protective Circuit Breaker - Grundfos BM Installations- Und Bedienungsanleitungen

BM/BMhp 6", BM/BMhp 8"
Star-delta starting
W2 B2
S
U
P
V2
R2
P
L
U2 Y2
Y
F W1 R1
O
R
V1 Y1
U1 B1
BK = Black
B=Black, R=Red, Y=Yellow
RD = Red
YE = Yellow
Fig. 14 Wiring diagram, star-delta connection

7.1 Frequency converter operation

Grundfos motors
Three-phase Grundfos MS and MMS motors can be connected to
a frequency converter.
If a frequency converter is to be used for booster modules
connected in series, it must be connected to the last module in
the flow direction.
We recommend Grundfos CUE. The CUE is a series of frequency
converters designed for speed control of a wide range of
Grundfos products, for example BM and BMhp.
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 transmitter cannot be
reactivated. This means that the motor will operate
like a motor without a temperature transmitter.
During frequency converter operation, we do not recommend to
run the motor at a frequency higher than the rated 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 rate of cooling liquid past the
motor is no longer ensured.
The permissible frequency ranges are 30-50 Hz and 30-60 Hz,
respectively.
During start, the maximum acceleration time from 0 to 30 Hz is 3
seconds.
During stop, the maximum deceleration time from 30 to 0 Hz is 3
seconds.
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
supplier or Grundfos.
10

8. Motor protection

The booster module must be connected to an effective motor-
protective circuit breaker which must protect the motor against
damage from voltage drop, phase failure, overload and a locked
rotor.
In power supply systems where undervoltage and variations in
phase symmetry may occur, a phase failure relay must also be
fitted. See section
The control circuit must always be made in such a way that all
modules are stopped if one module fails.
M

8.1 Setting of motor-protective circuit breaker

For cold motors, the tripping time for the motor-protective circuit
breaker must be less than 10 seconds (Class 10) at 5 times the
rated full-load current (I
nameplate.
In order to ensure the optimum protection of the submersible
motor, the motor-protective circuit breaker must be set in
accordance with the following guidelines:
1. Set the motor-protective circuit breaker to the rated full-load
current (I
2. Start the module, and let it run for half an hour at normal
performance. See section
module(s).
3. Slowly grade down the scale indicator until the motor trip point
is reached.
4. Increase the overload setting by 5 %.
The highest permissible setting is the rated full-load current (I
I ) of the module.
SFA
For modules wound for star-delta starting, the motor-protective
circuit breaker must be set as described above, but the maximum
setting must be as follows:
Motor-protective circuit breaker setting = rated full-load current x
0.58.
The highest permissible startup time for star-delta starting is
2 seconds.
15. Checking of motor and
/I ) of the module. See the module
1/1 SFA
If this requirement is not met, the motor warranty will
be invalidated.
/I ) of the module.
1/1 SFA
9. Before starting the booster
cable.
/
1/1