ABB
Synchronous motors |
Motors and Generators | ABB 13
Proven insulation system delivers ultimate reliability
ABB synchronous motors use the MICADUR
®
Compact
Industry (MCI) insulation system, which is based on the
vacuum pressure impregnation (VPI) method. The VPI and
curing of the completely wound and connected stator
winding with a specially formulated epoxy resin ensures
a sealed and homogenous insulation system. This results
in high dielectric strength, excellent heat transfer, and
the elimination of hazardous internal partial discharges.
We have been using the MCI system for more than 30 years.
It has been used on tens of thousands of our larger motors
and generators, which are operating successfully all over the
world. No primary insulation failures due to thermal aging
have been experienced. Thermal lifetime tests performed
on the MCI system show that its endurance substantially
exceeds IEC and IEEE requirements.
MCI insulated windings require very little maintenance.
In most cases it is only necessary to take steps to prevent
the ingress of moisture or dirt during periods when the motor
is not operating, as this could reduce the cooling ability of
the winding.
The systematic VPI process is highly effective:
–
Oven curing – after the VPI process has been completed,
stators and rotors are cured in an oven at high tempera-
ture. This produces very strong and stable insulation with
high mechanical and electrical strength. This is especially
important in order to resist inadvertent high stresses
from out-of-phase synchronization, transients and short
circuits.
Even the largest wound stators are impregnated
as complete units. This ensures that both the insulation
and the mechanical properties of the windings are excellent
– which means that they can withstand vibrations induced
by the driven equipment and the mechanical stresses
caused by transients such as short circuits.
Stator winding and insulation classes
Medium and high voltage windings up to 15 000 V are made
of form wound rectangular copper wire insulated with multiple
layers of glass-fiber reinforced mica-tape.
All materials used, including the VPI resin, exceed the
requirements of thermal class F. After insertion into the slots,
the coils are firmly held in place by means of slot wedges and
surge ropes at the coil heads prior to the VPI treatment.
The completed process assures a long and trouble-free
operating life.