CEI EN 60034-18-31

BILINGUAL

This part of IEC 60034 describes thermal endurance test
procedures for classification of insulation systems used in a.c. or
d.c. rotating electrical machines with indirect cooling and
form-wound windings.

The test performance of a candidate insulation system is
compared to the test performance of a reference insulation system
with proven service experience.

The test procedures described in IEC 60034-18-31 are intended to
compare the thermal endurance performance of the mainwall
insulation between conductor(s) and ground and, where required by
the design of the coil or bar, the insulation between the
turns.

The test is not intended to simulate the in-service mechanical
stresses experienced by the endwinding bracing or support
materials. It does not include the evaluation of thermomechanical
deterioration by expansion and contraction of insulation during
temperature cycling.

IEC 60034-18-1 describes general testing principles applicable
to thermal endurance testing of insulation systems used in rotating
electrical machines. The principles of IEC 60034-18-1 are followed
unless otherwise stated in IEC 60034-18-31.

The thermal class for the insulation system refers to its
maximum allowed ("hot spot") temperature. The average temperature
measured in service should not exceed the allowed temperature rise
according to IEC 60034-1.

NOTE 1 Large machines, especially synchronous generators using
bars, may require special thermal evaluation test procedures which
are not included in this part.

NOTE 2 Recommended parameters for the diagnostic test may be
applied according to IEC 60034-18-42 to formwound coils designed
with Type II insulation systems for use in converter
applications.