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Description / Abstract:
This guide describes a procedure that may be used to evaluate
and compare insulation systems used, or proposed for use, in large
ac electric machines.
The tests outlined herein are applicable to the groundwall
insulation systems applied to form-wound, preinsulated armature
(stator) winding coils and/or bars of generators, motors, and
synchronous condensers rated 2300 V or higher.
The basic component of these insulation systems is usually mica
combined with reinforcing, bonding, and impregnating materials.This
guide is based on the experience of the industry with mica-based
systems; any evaluation of other insulation systems should,
however, consider the recommendations of this guide.
This guide is not intended for use as a manufacturer's quality
assurance test plan. Nor should it be used for specifying or
procuring armature winding coils/bars.
Purpose
During operation, an insulation system is subjected to
electrical, thermal, mechanical, and environmental stresses that
act and interact to cause irreversible changes in the properties of
the insulation. The applied stresses initiate aging mechanisms that
eventually lead to failure. The purpose of this guide is to provide
a means of evaluation in which groundwall insulation systems, as
described in 1.1, are exposed to influencing factors that simulate
or are characteristic of actual service conditions. This guide
establishes the basis for evaluating the aging of the electrical
insulation system as a result of these influences.