What is difference between Type NL (K-4 rated) or NLP (K-13 rated) Transformers compared to standard Low Voltage Distribution Transformers?

Issue:
K Rating on Low Voltage Transformers

Product Line:
LV Transformers

Environment:
Product sold in North America

Cause:
Harmonic Energy generation in Electrical Systems

Resolution:
SquareD/Schneider Electric`s line of K-rated transformers are designed to minimize the eddy current, or stray losses within the Transformer.  It is these eddy/stray losses that are affected by non-linear loads such as computers, fax machines, and other office electronic equipment. A k13 rated transformer will accommodate a higher level of harmonics without exceeding its temperature rating than a k4 rated unit of the same kVA, voltage and temperature class.
K rated Delta Wye units will operate at full load in circuits rich in harmonics without exceeding the temperature rating of their insulation systems.  Once the loading goes above 80% of transformer capacity and a high level of harmonics are present, k4 units should be considered to prevent overheating.  At loading levels above 90% a k13 unit should be used. The recommendation to use k Factor Transformers for computer loads assumes high harmonics and high loading levels.

Released for:Schneider Electric Canada