Guide for Testing Turn Insulation of Form-Wound Stator Coils for Alternating-Current Electric Machines
|Publication Date:||9 February 2004|
This guide makes suggestions for testing the dielectric strength of the insulation separating the various turns from each other within multiturn form-wound coils to determine the acceptability of the coils. Typical ratings of machines employing such coils normally lie within the range of 200 kW to 100 mW (270 to 135 000 hp). Test voltage levels described herein do not evaluate the ability of the turn insulation to withstand abnormal voltage surges, as contrasted to surges associated with normal operation. The repetitive voltage surges (spikes) associated with adjustable frequency drives (AFD) are also not addressed here. This guide applies to
a) Individual stator coils after manufacture.
b) Coils in completely wound stators of original manufacture.
c) Coils and windings for rewinds of used machinery.
d) Windings of machines in service to determine their
suitability for further service (preventivemaintenan
The purpose of this guide is to
a) Define surge/impulse testing as applied to the windings of an electric machine.
b) Review the service conditions that affect voltage levels in a coil.
c) Recommend devices suitable for measuring surges, with precautions to avoid erroneous results.
d) Describe various points where surge testing may be performed.
e) Present suggested surge test levels for various types of electric machines.