CSA C235:19 pdf download – Preferred voltage levels for AC systems upto50000V.
1 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.
3 Definitions The following definitions shall apply in this Standard: Nominal voltage — a suitable approximate value of voltage used to designate or identify a system. Point of connection — a reference point on the electric power system where the user’s electrical facility is connected. Note: For clarity, the point of connection is the ownership boundary between the public power system and the customer facility. Utility contractual agreements might specify a different point for delineating voltage responsibility. Steady-state — RMS voltage assessed over contiguous 10-min intervals. Intervals with voltage interruptions of any duration are excluded. Utilization equipment — equipment that utilizes electrical energy for mechanical, chemical, heating, lighting, or similar useful purposes. Utilization voltage — the phase-to-phase or phase-to-neutral voltage at the points where utilization equipment is connected to the power supply. Voltage interruption — a reduction of the RMS supply voltage of all phases to less than 10% of the nominal voltage.
4 General In the interpretation of this Standard it is important to bear in mind the sense of usage for the terms “normal”, “extreme”, and “other operating conditions”: a) Normal operating conditions: Where voltages lie within the indicated limits under this heading, no improvement or corrective action is required. b) Extreme operating conditions: Where voltages lie outside the indicated limits for normal operating conditions, but within the indicated limits for extreme operating conditions, improvement or corrective action should be taken. c) Other operating conditions: Where voltages lie outside the indicated limits for extreme operating conditions, improvement or corrective action should be taken in accordance with the policies and procedures of the supply authority. The urgency for such action will depend on many factors such as location and nature of the energy exchange or circuit involved, extent to which limits are exceeded with respect to voltage levels and duration, etc. Note: Distribution system operating procedures/requirements are ultimately determined by the local power system operator and might supersede the voltage ranges defined herein. For example, distributed energy resource (DER) might be required to operate outside the extreme operating voltage range; such conditions might be accepted by distribution system operators if customers are not adversely impacted.CSA C235:19 pdf download.
