Preferred Voltage Levels for AC Systems, 0 to 50 000 V
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This is the second edition of CSA Standard C235 (now CAN3-C235) and it supersedes the first edition, which was published in 1969.
Prior to 1969 the need for a recognized set of voltage standards in Canada had been the concern of the electrical industry throughout its history. In preparation for the first edition many studies, questionnaire surveys, and discussions of national scope were conducted. Since its initial publication in 1969 this Standard has served well as a guide to those who are involved in the problems of applying a great variety of electrical devices and equipment to an equally great variety of voltage levels across the country. Improved equipment design ratings and controlled system design levels have both resulted.
This second edition calls for closer control of voltage variation for circuits between the 1000 and 50 000 V levels. Otherwise, it is essentially the same as the first edition.
This Standard establishes voltage standards for AC Systems in Canada to provide a guide:
(a) To national committees on utilization and control equipment or devices for establishing standard ratings of such equipment or devices on a basis coordinated with standard systems;
(b) To system designers so that new systems will be designed to accommodate standard ratings of equipment and devices;
(c) To system operators and to electrical energy users for determining 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.