addition, varnishing helps windings keep their form and
2. Coil side separators, which are placed on top of
coil sides as they are laid into slots to prevent
adds mechanical strength. The procedures for
two coil sides from touching one another within
varnishing new windings are given in table 7-7.
the same slot. May be made of flat silicon glass
Polyamide Paper
insulation or formed (curved) polyamide paper.
Before placing windings in a stripped stator or
3. Slot wedges, which are used to close up slots
armature the slots must be insulated to prevent current
once all coil sides are inserted. They may be
leakage to ground and to insulate the separate windings
made of flat silicon glass insulation or formed
from one another. Polyamide paper is available in
(curved) polyamide paper.
various thicknesses and dielectric strengths for this
4. Phase insulation, which is used to prevent the
purpose.
ends of adjacent coils from touching one
another. It is made of .007 inch polyamide
There are four types of paper insulation used in
paper.
winding.
ELECTRICAL TESTS
1. Slot insulation, which is used to separate the coil
sides in the slot from the laminations. Prepared
Electrical tests are performed on new windings to
ensure connections are proper and that workmanship is
from two 7 mil (0.007") pieces of polyamide.
Table 7-7.--Varnishing Procedures
7-32
