Preface

Revised October 2014

This is the seventh edition of CSA C50, Mineral insulating oil electrical for transformers and switches. It supersedes the 2008 edition of the same title and the 1997, 1976, 1965, 1958, and 1938 editions, which were titled Insulating oil electrical for transformers and switches.

The changes introduced in this edition are the following:

a) Requirements for the detection of potentially corrosive sulphur have been added;

b) Requirements for the detection of dibenzyldisulphide (DBDS) have been added;

c) Requirements for the detection of metal passivators in oxidation inhibitors have been added; and

d) Requirements concerning additives in oil have been added.

It needs to be recognized that the tests specified in this Standard do not indicate the relative service lives of different oils. Purchasers should use these tests to determine the characteristics of oils that have been found by experience to be satisfactory and to detect any significant variations in the characteristics of further shipments of such oils.

Scope

1.1
This Standard specifies the requirements for mineral oil of petroleum origin for use in transformers, oil circuit breakers, or other electrical equipment (excluding high-voltage cables) requiring a liquid insulating and cooling medium.

1.2
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 by 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.