Requirements may call for a Transformer of a higher than standard efficiency level
Applies to Ventilated Transformers by SquareD/Schneider Electric
CSL-3 was a Proposed Ruling of Efficiencies which is sometimes used as a specification
Candidate Standard Level 3 (CSL-3) was an older (2007 timeframe) proposed Efficiency standard that some non SquareD/Schneider Electric Transformer manufacturers used in the past as a marketing tool for their Energy Efficient Transformers. SquareD/Schneider Electric had never used the CSL-3 standard as a description or specification. The entire industry has adopted an equivalent (or better) product than the "proposed" but never formally adopted CSL-3 “standard”. See attached bulletin for further information. The current EX series Transformers from SquareD/Schneider Electric conform to the current Department of Energy (DOE) 2016 Efficiency Standards for Low Voltage Ventilated Transformers. CSL-3 was not before, and is not now, a relevant factor.