Mas Grup
6
6.4.1. Motor Connection Diagram
Motors requiring high moments at start up shall not be connected star-
delta
Frequency controlled motors, require high moment at start up and have to
be cooled properly at low speeds. Provide the necessary cooling for the
motors.
Figure 4:
Electric Connection Diagram
Electrical circuit
Motor
U (Volt)
230/400 V 400 V
3 x 230 V
Delta
3 x 400 V
Star
Delta
6.4.2. Motor Protection
• Three phased-motor shall be connected to power supply.
• Wait the motor to cool down when thermic protected motor breaks in
circuit due to the overheating. Make sure the motor does not start
automatically until it cools completely
• In order to protect the motor from overcharging and short circuit use a
thermic or thermic-magnetic relay. Adjust this relay to the nominal
current of the motor.
Electrical equipments, terminals and the components of the control
systems may carry electric current even though they are not
operating. They may cause deadly and serious injuries or
irreparable material damages.
6.5. Coupling alignment
6.5.1. General
For a proper operation of a pump group, a good alignment of the coupling
is necessary. Vibration, noise, overheating of the bearings, overcharge
problems can be attributed to the misalignment of coupling or using an
improper coupling.
Flexible coupling does not correct the axial misalignments between
the pump and the motor axes. However, it allows pinpointing the
misalignments.
In order to avoid overheating, vibration, noise and wearing of the
rolling bearings, alignment of the coupling has to be made properly
and checked often.
Do not use a different coupling other than the original type installed
on pumping group.
6.5.2. Method of coupling alignment
In order to make the alignment of the coupling, it is required to have at
least two pieces of about 10 cm tall, smooth-edged metal parts (e.g. a
steel ruler or a gauge stick) and one precision calipers. (Figure 3) (For
more precision alignments, special apparatus can be used).
Coupling misalignments in general are of two kinds:
1. Paralel Axis Misalignment
(Figure 5)
In order to control parallel axis misalignment, a smooth edged gauge stick
is pressed axially over the upper half of the coupling. Then, the gauge
stick is checked for the other half of the coupling. For alignment, the
gauge stick shall be in contact with both of the halves at the same time.
This procedure shall be repeated for four sides of the coupling. (i.e. top,
bottom, left and right sides of the coupling). When all four sides give
reasonably accepted results, alignment of the coupling has been
ensured.
2. Angular Misalignment
(Figure 6)
In order to control the angular misalignment, the distance between the
two halves of the coupling is measured in both horizontal and vertical
planes. Measurements taken at four points shall be in agreement for the
alignment.
Misalignments can be in horizontal or vertical planes. Misalignments
in horizontal plane can be fixed by placing sheet iron at the bottom
of the pump or motor base, while misalignments in vertical plane
can be fixed by sliding the pump or the motor in horizontal plane.
Figure 5: The Control of the Coupling Alignment in Horizontal and
Vertical Planes
Figures below illustrate the possible coupling misalignments and
the methods to correct them.
Figure 6:
Paralel Axis Misalignment in Horizontal Plane and Its
Correction
Figure 7:
Angular Misalignment in Vertical Plane and Its Correction
