IEEE 522-2004 pdf download IEEE Guide for Testing Turn Insulation of Form-Wound Stator Coils for Alternating-Current Electric Machines
1.Overview
1.1 Scope
This guide makes suggestions for testing the dielectric strength of the insulation separating the various turnsfrom each other within multiturn form-wound coils to determine the acceptability of the coils. Typical rat-ings of machines employing such coils normally lie within the range of 200 kW to 100 mW (270 to 135 000hp). Test voltage levels described herein do not evaluate the ability of the turn insulation to withstandabnormal voltage surges, as contrasted to surges associated with normal operation, The repetitive voltagesurges (spikes) associated with adjustable frequency drives (AFD) are also not addressed here. This guideapplies 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 (preventivemaintenance testing).
1.2 PurposeThe purpose of this guide is to
aDefine surge/impulse testing as applied to the windings of an electric machine.
bReview the service conditions that affect voltage levels in a coil.
Recommend devices suitable for measuring surges, with precautions to avoid erroneous results.
dDescribe various points where surge testing may be performed.
Present suggested surge test levels for various types of electric machines.
2.References
ASTM D1711-02,Standard Terminology Relating to Electrical Insulation.
IEEE Std 510″-1983 (Reaff 1992), IEEE Recommended Practice for Safety in High-Voltage and HighPower Testing.
3. Service conditions
3.1 Operating stress
The maximum operating (line frequency) voltage difference between turns in a coil depends upon the voltage between coil terminals and on the internal construction of the coil.
3.2 Transient stress
A second, and less predictable, voltage difference between turns can be caused by voltage transients. Additional information on the nature of such transients and the associated turn voltage distribution may be foundin a number of articles cited in the bibliography in Annex C. Steep-front voltage waves due to arcing in theassociated circuit can be damaging to turn insulation since a substantial portion of the wave can appearacross the turn insulation of the coil(s) near the line terminals.
3.3 Withstand requirements
The voltage difference that turn insulation must withstand, therefore, covers a broad range from less than100 V in normal operation to as much as several thousand volts under transient conditions. At the lower endof this range all that is needed is physical separation, whereas at the other. insulation having considerabledielectric strength is needed.
IEEE 522-2004 pdf download
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