Setting Of Motor Starter; Liquid Filling, Module Venting And Checking Of Direction Of Rotation; Operation; Limitations To Operation - Grundfos BM 6'' Betriebsanleitung

6.2 Setting of motor starter

To ensure the best protection of the submersible motor, the set-
ting of the motor starter should be carried out as follows:
The overload unit should first be set to 0.9 times the motor full
load current. If the motor starter does not trip out at this setting,
the overload unit should be set down until the tripping point is
reached, and then it should be adjusted up by 5% from the trip-
ping point.
If the motor starter trips out at the setting of 0.9 times the full load
current, check voltage and current. If the voltage is correct and
the current is less than the stated full load current, set the over-
load up until the tripping point is reached, and then it should be
adjusted up by 5%.
The final current must not exceed the full load current.
7. Liquid filling, module venting and checking of
direction of rotation
Booster modules with vent valve:
The booster module(s) is/are filled with water/liquid through the
suction port of module 1 (fig. 4).
1. Slacken the vent valve of the booster module.
2. Pour water/liquid into the module until it starts running out of
the vent valve.
3. Tighten the vent valve.
Booster modules without vent valve:
Booster modules without vent valve are vented automatically via
the internal by-pass system.
Now a check must be made to determine the direction of rotation:
1. Close the isolating valve on the discharge side of module 1
(figs. 4 to 7) to approx. 1/3 of maximum flow.
2. Start module 1 and record discharge pressure and flow read-
ings.
3. Stop the module and interchange two of the phases to the mo-
tor.
4. Restart the module and re-record discharge pressure and flow
readings.
5. Stop the module.
Compare the results taken under points 2 and 4. The connection
which gave the larger pressure and flow is the correct direction of
rotation.
The check for the direction of rotation should last for the shortest
possible time.
If the booster unit has several modules, starting and rotation
checks are made in the order 1-2-3-4 until all modules are run-
ning. When module 2 is checked, module 1 must be running.
When module 3 is checked, modules 1 and 2 must be running,
etc.
If modules in series are also connected in parallel (fig. 6), the di-
rection of rotation of each section connected in series should be
checked.
After having checked the direction of rotation, stop the modules in
the order 4-3-2-1.
The booster unit is now ready for operation.

8. Operation

The booster modules must be started in the order 1-2-3-4 at inter-
vals of 1 or 2 seconds.
The modules must be stopped in reverse order, i.e. 4-3-2-1, at
the same intervals.
Module 1 is always the first module on the suction side.
The start/stop intervals stated will reduce water hammering in the
system.
If water hammering is a problem in the modules during stopping,
it is recommended to install a diaphragm tank.
During operation, it must be checked that the inlet pressure is as
estimated and never lower than 0.5 bar (5 metres head) for
BM 4", BM 6", BMB 4" and BMB 6" and 1 bar (10 metres head) for
BM 8" and BMB 8".
8
When not being used, all modules should be filled with water as
all internal bearings are water lubricated.
If the booster unit is taken out of operation for a long period, the
modules should be flushed through with clean water. The mod-
ules are then left with clean water until they are to be used again.
The booster modules are not allowed to run against a
closed discharge valve as this will cause an increase
in temperature/formation of steam in the pump which
may cause damage to the pump and the motor.
If there is any danger of the modules running against
a closed discharge valve, a minimum liquid flow
through the pump should be ensured by connecting a
bypass/a drain to the discharge pipe. The drain can
for instance be connected to a tank.
The total pressure and flow of modules connected in series
should never be changed by stopping one or more of the mod-
ules. If different pressures or flows are required, it is recom-
mended to proceed as follows:
a) In the case of GRUNDFOS booster modules, fit a bypass be-
tween two modules (see fig. 7).
Stop the module(s) which is/are not required and close the iso-
lating valves on either side of the module.
If the module(s) taken out of operation will not be used for long
periods, it is recommended to flush this/these module(s)
through with clean water.
If a module is taken out of operation as described, it should al-
ways be the last one in the series.
b) Fitting a pressure reducing valve or a pressure relief valve to
the discharge pipe.
The following minimum flows must be ensured at
all times:
BM 4" and BMB 4": 0.8 m³/h.
BM 6" and BMB 6": 5.5 m³/h.
BM 8" and BMB 8": 18.5 m³/h.
Please note that the minimum flows stated do not ensure opti-
mum conditions and should be avoided, see section 8.1 Limi-
tations to operation.
Furthermore, the operating pressure and the maximum inlet
pressure in sleeves must not exceed the values stated in sec-
tion 8.1 Limitations to operation.
If there is any danger of the modules running against a closed
discharge valve, a minimum liquid flow through the pump
should be ensured (see above). Furthermore, the liquid tem-
perature must not exceed the values stated in section

8.1 Limitations to operation.

If a module of a booster unit in series in a system with two or
more series connected in parallel without bypass fails, the whole
booster unit in question must be switched off, because all mod-
ules connected in series must develop the same pressure. Other-
wise, the module that develops a too low pressure will stop and
the next motors in the series will burn because of insufficient
cooling. See also recommended pipework connection in fig. 6.
8.1 Limitations to operation
The performance of the modules should always be kept within the
recommended flow and pressure ranges of each individual pump:
Recommended flows at 25°C
Type
50 Hz
BM 3A/BMB 3A 0.8-4.4
BM 5A/BMB 5A 2.5-6.8
BM 8A/BMB 8A 4.0-10
BM 17/BMB 17 8.0-24
BM 30/BMB 30 15-38
BM 46/BMB 46 24-60
BM 60/BMB 60 35-75
BM 77/BMB 77 40-100
BM 95/BMB 95 50-120
BM 125/BMB 125 70-160
m³/h
60 Hz
1.0-5.4
3.0-8.4
4.8-10
8.0-29
18-45
28-72
40-90
48-120
60-140
80-180