Connection; Connection For Variable Speed Drive; Balancing - ABB MT serie Installations- Betriebs Und Wartungshandbuch

2.4 Connection

Normal machine design has the terminal box on top
with cable entry possible from both sides.
Some machines are available with top mounted terminal
boxes rotatable 4 x 90°, and some with side mounted
terminal boxes.
Availability of these solutions is described in the product
catalogues.
Unused cable entries must be closed.
As well as main winding and earthing terminals, the
terminal box can also contain connections for
thermistors, standstill heating elements, bimetallic,
switches, or PT 100 resistance elements.
WARNING
Voltage may be connected at standstill inside the
terminal box for heating elements or direct winding
heating.
Connection diagrams for auxiliary elements are found
inside the terminal box cover or in additional labels on
the frame of the machine.
WARNING
The capacitor in single-phase motors can retain
a charge that appears across the motor terminals,
even when the motor has reached standstill.
2.4.1 Connection for variable
speed drive
Variable speed drives cause higher voltage stresses
than the sinusoidal supply on the winding of the motor
and may cause high frequency shaft voltages and
bearing currents. Therefore the winding and the bearing
insulation of the motor as well as the fi lter at the
converter output must be dimensioned according to
"Selection rules for VSD applications/Insulation"
(3GZF500930-2), available on request from ABB.
In variable speed drives the motor (Pn > 30 kW) must
be cabled by using shielded symmetrical cables and
cable glands providing 360° bonding (also called EMC
glands). More information can be found in ABB's
manual "Grounding and cabling of the drive system"
(3AFY61201998).
In frequency converter applications motor frame
external earthing must be used for equalising the
potential between the motor frame and the driven
machine, unless the two machines are mounted on the
same metallic base.
For motor frame sizes above IEC 280, use 0.75 x
70 mm fl at conductor or at least two 50 mm
conductors. The distance of the round conductors must
be at least 150 mm from each other.
This arrangement has no electrical safety function; the
purpose is to equalise the potentials. When the motor
and the gearbox are mounted on a common steel
fundament, no potential equalisation is required.
ABB / Low Voltage Motors / Manual 12-2004
Driven machinery
To comply with EMC-requirements, use only cables and
connectors approved for this purpose. (See instruction
for frequency converters.)
The highest permissible rotational speed of a cast iron
motor used in variable speed drive (M2BA/M3BP) must
not exceed maximum permissible speeds as stated in
the table 2 below or the speed stamped on the rating
plate. For information on the highest permissible
rotational speed for other motor sizes and types, please
contact ABB. Bearing lubrication should follow the
directions mentioned later.
Frame
size
280
315
355
400
450
Table 2
If there is uncertainty concerning the suitability of the
motor for the variable speed drive, please contact ABB.
WARNING
The maximum operating temperature of the
grease and bearings must not be exceeded.

2.5 Balancing

The rotor of the machine is dynamically balanced.
As standard, balancing has been carried out using half
key, and the shaft is marked with a RED tape, with the
text "Balanced with half key". In case of motors
delivered without any tape defi ning the type of
balancing, these motors are also balanced with half
key.
To avoid vibration the coupling-half or pulley must be
balanced with half key after the keyway has been
machined.
In the event of balancing with full key the shaft is
marked with a YELLOW tape, with the text "Balanced
2
round
with full key".
In case balancing without key, the shaft is marked
with a BLUE tape, with the text "Balanced without
key".
Potential equalisation
Plate/strip Cables/wires
Speed r/min
2 pole 4 pole
3600 2600
3600 2300
3600 2000
3600 1800
3600 1800
7 – GB