Minimum efficiency values for liquid-filled distribution transformers
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This is the second edition of CSA C802.1, Minimum efficiency values for liquid-filled distribution transformers. It replaces the previous edition published in 2000.
The methodology of Total Ownership Cost (TOC) is presented as a means by which electric utilities may continue to purchase transformers that best suit projected provincial or local conditions. Such conditions include utility load, projected peak loads, generation capability and availability, generation reliability, and fuel prices, among other factors.
A given electric utility assigns multipliers to the no-load and load loss values which produce capitalized present values (PV) of those losses for the expected life of the transformer. The formula by which multipliers are assigned is known as the Loss Evaluation Formula. The present values of the losses are added to the first cost to derive the TOC of a given transformer. By using TOC to minimize overall costs, electric utilities have, at the same time, reduced losses in their transformers.
TOC methodology is not readily implemented in many non-utility applications and, in such cases, the minimum efficiencies provided in this Standard are more practical. The values given approximate those that typically arise when deriving efficiencies from the losses related to TOC calculations. Thus, though first cost may be increased, the user will amortize the increase because of the lower running costs resulting from lower losses. Utilities change their evaluation formulas as circumstances change, and the efficiency values in this Standard will be changed accordingly at appropriate intervals.
This Standard was prepared by the Subcommittee on Liquid-Filled Distribution Transformer Efficiency under the jurisdiction of the Technical Committee on Industrial Equipment and the Strategic Steering Committee on Performance, Energy Efficiency, and Renewables, and has been approved by the Technical Committee.
This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group.
This Standard specifies energy efficiencies for liquid-filled distribution transformers. The total ownership cost (TOC) methodology is recommended as the means for achieving these energy efficiencies, particularly for use by electric utilities. This Standard also specifies an optimal method for nonutility users, based on a modified TOC methodology that meets the conditions of energy cost.
The transformers to which this Standard applies are single-phase and three-phase, 60 Hz, liquid-filled distribution transformers, rated at 10-833 kVA for single-phase and at 15-3000 k/VA for three-phase, insulation class 34.5 kV and less. Minimum low voltage ratings are shown in Table 1.
This Standard describes special features that influence efficiency, and provides for the necessary modifications to the tabulated efficiency values.
This Standard addresses the test methods and procedures for determining the transformer efficiencies.
This Standard does not apply to autotransformers, testing transformers, welding transformers, furnace transformers, rectifier transformers, network transformers, or grounding transformers. Also excluded are transformers with special core/coil designs required by dimensional constraints, transformers with tap ranges greater than 15%, transformers with frequencies other than 60 Hz, and step-voltage regulators.
In this Standard, shall is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; should is used to express a recommendation or that which is advised but not required; and may is used to express an option or that which is permissible within the limits of the standard.
Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.
Notes to tables and figures are considered part of the table or figure and may be written as requirements.
Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.
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