NEMA ANSI C84.1 pdf free download

NEMA ANSI C84.1 pdf free download.Electric Power Systems and Equipment一 Voltage Ratings ( 60 Hertz)
5 Explanation of Voltage Ranges
For any specific nominal system voltage, the voltages actually existing at various points at various times on any power system, or on any group of systems, or in the industry as a whole, usually will be distributed within the maximum and minimum voltages shown in table 1. The design and operation of power systems and the design of equipment to be supplied from such systems should be coordinated with respect to these voltages so that the equipment will perform satisfactorily in conformance with product standards throughout the range of actual utilization voltages that will be encountered on the system. To further this objective, this standard establishes, for each nominal system voltage, two ranges for service voltage and utilization voltage variations, designated as Range A and Range B, the limits of which are given in table 1. These limits shall apply to sustained voltage levels and not to momentary voltage excursions that may result from such causes as switching operations, motor starting currents, and the like.
5.1 Application of Voltage Ranges
5.1.1 Range A—Service Voltage
Electric supply systems shall be so designed and operated that most service voltages will be within the limits specified for Range A. The occurrence of service voltages outside of these limits should be infrequent.
5.1.2 Range A—Utilization Voltage
User systems shall be so designed and operated that with service voltages within Range A limits, most utilization voltages will be within the limits specified for this range.
Utilization equipment shall be designed and rated to give fully satisfactory performance throughout this range.
5.1.3 Range B—Service and Utilization Voltages
Range B includes voltages above and below Range A limits that necessarily result from practical design and operating conditions on supply or user systems, or both. Although such conditions are a part of practical operations, they shall be limited in extent, frequency, and duration. When they occur, corrective measures shall be undertaken within a reasonable time to improve voltages to meet Range A requirements.
Insofar as practicable, utilization equipment shall be designed to give acceptable performance in the extremes of the range of utilization voltages, although not necessarily as good performance as in Range A.
5.1.4 Outside Range B—Service and Utilization Voltages
It should be recognized that because of conditions beyond the control of the supplier or user, or both, there will be infrequent and limited periods when sustained voltages outside Range B limits will occur. Utilization equipment may not operate satisfactorily under these conditions, and protective devices may operate to protect the equipment.
When voltages occur outside the limits of Range B, prompt, corrective action shall be taken. The urgency for such action will depend upon many factors, such as the location and nature of the load or circuits involved, and the magnitude and duration of the deviation beyond Range B limits.
NEMA ANSI C84.1 pdf download.