Frames 63 to 100 L with prefixes AD are of
diecast aluminum. Foot mounted stators
have integral feet. TEFC & TE motors have
integral longitudinal ribs for effective heat
transfer. Specially designed roller table
motors for steel plants have circular ribs to
avoid deposition of dust & slags between the
The stator & end shields are machined to
close tolerances for providing perfect
Terminal boxes of frames up to 132M are of
diecast aluminum alloy. Frame 160 & above
have cast iron terminal box. All joints in
terminal box are sealed with gaskets.
Motors above frame 160 have drain holes at
their lowest position as a standard features.
Both stator and rotor cores are made of
high quality magnetic steel
Stator and rotor (for SR motors) windings
consists of modified polyester enamel
covered copper wire. Frame 280 and above
are wound with dual coat copper wire as per
IS: 13730-13. Motors wound with double
glass covered conductors are also available
on order for frame 160 and above only.
All motors are made with class F insulation as
a standard feature.
The slot liners are either provided with
double cuffing or edge binding at the slot
mouth portion to strengthen the insulation.
For frame 160 & above class F varnish or
resin with vacuum pressure impregnation is
used for impregnating the winding.
Epoxy gel coat is sprayed on all winding
overhangs (in frames 200 and above) to
provide mechanical rigidity to the winding to
withstand the electrical and mechanical
Surge testing is carried out on all windings in
addition to all other tests ensuring
healthiness of windings.
The overhangs of SR rotors are banded with
resi-glass tape under controlled tension, to
prevent flaring under centrifugal force
caused by over speed.
The rotor of SCR motors are made of
pressure diecast aluminum (or alloy in case
of special designs) up to frame ND355L.
Rotors of specific polarity are made of
electrolytic copper & copper alloy bars &
rings connected by high quality silver
The rotors of SR (slipring) motors are wound
with copper wire or strip. (See in winding and
Slipring And Brushgear
SR motors are provided with slipring and
brush gear arrangement. The Sliprings are
moulded in epoxy-based insulation and have
excellent stability at high temperature and
have very good anti tracking property.
Fabricated Sliprings as per Steel Plant's
specification (IPSS) are also available on
request for frames 160&above.
3 Nos. brush holders with 2 nos each metal
graphite carbon brushes are provided- one
on each ring phase. The grade of carbon
brush is M15E of Assam carbon or
equivalent. Each carbon brush is marked
with its grade and the line of wear, which
helps in identifying replacement need.
The brush holders are made of brass. For
160 to 200, self tension adjustment brush
holders are used . Frames 225 and above
have adjustable arms to suit the range of
slipring diameter. This always facilitates
angular adjustment of arms for radial
placement of brushes even after reduction in
diameter of slipring, resulting out of any
rework carried out in service. The brush
tension is adjustable with the help of
adjustable nuts provided on the brush arm.
The sizes of brush and recommended force
for all frames are as given in the table: