Preface:

This is the third edition of CSA C235, Preferred voltage levels for AC systems up to 50 000 V. It supersedes the previous editions, published in 1969 and 1983.

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.

Scope:

1.1
This Standard establishes steady-state voltage operating ranges at point of connection for AC power systems in Canada. It serves to provide guidance
a) to national committees on utilization and control equipment for establishing standard ratings of such equipment on a basis coordinated with power system voltages;
b) to power system designers so that new systems will be designed to accommodate standard ratings of equipment and devices;
c) to power system operators and to electrical energy users for determining suitable voltage performance and the need for corrective measures, with respect to existing systems, to accommodate current designs of equipment and devices; and
d) towards a uniform system of voltage selections in the country without any suggestion that each utility will supply every voltage listed. The establishment of standards on this basis is aimed at future development towards more uniformity on a national basis.

This Standard includes nominal voltages and supply steady-state voltage ranges at point of connection under both normal and extreme operating conditions.

This Standard does not include voltage operating ranges at utilization points.

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 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.