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Description / Abstract:
Scope and Purpose
This recommended practice outlines test procedure for the
evaluation of the impulse voltage capability of insulation systems
of form-wound alternating current rotating electrical
machinery.
This test procedure forms a base for the accumulation, analysis,
and reporting of information concerning impulse voltaee withstand
strength of around and turn insulation, both new and aged. The
immediate goal is a better understanding of relevant aging
mechanisms: the ultimate aim of this document is to aid in
estimating life of an insulation system under specified service
conditions.
It must be emphasized that this test procedure is intended, at
this time, for trial use. Future revisions, made after experience
with it, should result in more definitive specifications being
possible.
This procedure recommends the use of multi-factor aging, tests,
combining thermal and electrical aging in order to address the
withstand capability of micaceous insulation. Variations of this
procedure may be tried, such as for voltage ratings other than 6.9
kV and 13.8 kV for turn insulations other than mica. and for
various impulse wave forms.
The procedure is primarily directed toward providing a
qualification test for the turn insulation in regard to its ability
to withstand impulses that might be impressed on the terminals of a
machine and that result from switching surges, lightning., or other
disturbances. It will also provide information on the ability of
the ground insulation to withstand impulses. In addition, the test
model used in the tests described hereimi will be suitable for
testing the strand insulation. if that is desired, althoug.h it is
not a ftmnctioii of this qualification test procedure.