IEEE 3001.5-2013 pdf download IEEE Recommended Practice for the Application of Power Distribution Apparatus in Industrial and Commercial Power Systems
3.Introduction
This recommended practice provides information on the requirements for, and application of, majorapparatus utilized in industrial and commercial electric distribution svstems. More detailed information onthis type of apparatus is available from the American National Standards Institute (ANSI), the NationalElectrical Manufacturers Association (NEMA),and nationally recognized testing laboratories (NRTLs)such as Underwriters Laboratories, Inc., (UL) or Factory Mutual (FM), as well as from manufacturerspublications
Ihe engineer should make basic decisions in the choice of equipment for a particular electric system. Thedecision-making process should entail all those factors involved in designing and maintaining an electricpower system, such as safety, protection, continuity of service, reliability, security, protective coordination.initial installed cost, procurement time to meet the schedule, flexibility, staffing, and cost for operating andmaintenance. Energy cost, conservation, and environmental protection should be considered in initial plantdesign and equipment. For information related to energy cost and conservation, refer to IEEE Std 141TM.1993(IEEE Red BookTM) Chapter 14.
The engineer should anticipate how operating personnel will need to interface with energized equipmentand the work that may be required to be performed in proximity to the equipment while energized. Suchwork must be conducted in accordance with NFPA 70E, whose purpose is to “provide a practical safeworking area for employees relative to the hazards arising from the use of electricity.” Procedures for riskassessment and the determination of required personal protective equipment (PPE) for specific tasks areprovided in this standard. The PPE requirements can be affected significantly by the prospective arc flashavailable within the electrical equipment. Equipment choices may be available to the designer to reduce therisk of arc flash and/or reduce its severity to create a safer work environment NFPA 70E Annex 0addresses safety-related design requirements. For information regarding the determination of arcingcurrents and arc flash energy for the purpose of selecting PPE, refer to IEEE Std 1584TM-2002.
3.1 Equipment installation
Electric equipment should be installed in a manner that is safe yet readily accessible to qualified personnel.Sufficient working space should be provided and aintained about all electric apparatus to permit ready
and safe operation and maintenance of such equipment. Minimum working clearances around electricaequipment as required by the National Electrical Code (NEC@) (NFPA 70) shall be considered fordesign and installation.
Installations in industrial plants require that adequate aisles, hatchways, wall openings, etc.. be provided foreasy removal and replacement of all electric equipment. For medium-voltage switching equipment, extremecare should be exercised in setting, grouting, aligning, and leveling the floor channels in order to preventstressing insulators and bus structures and to provide for easy insertion and removal of the apparatus. Floorarea in front of switchgear should be level or have only a moderate slope away from the equipment foradequate drainage.
Special attention should be given to the floor under and in front of any equipment that is required to roll inand out of the enclosure. More detailed installation procedures are given in NEMA PB 2.1-2007. Ifcquipment is to be stored or installed in locations where internal condensation may occur, suitable internaheating should be provided (NEMA PB 2.1- 2007,Section 3)
Article 450 of the NEC outlines the installation requirements for transformers of various types. In someindustrial plants, the unit substation transformer is located outside a pressure-ventilated switchgear roomwith a secondary throat connection for buswork through the wall. This pressure-ventilated switchgear roommay also house motor-control centers, panelboards, and other electrical and electronic equipment inaddition to the switchgear. This particular type of design would be used for the following reasons:
0)Protection of electric equipment from the accumulation of dirt, dust, and other foreign material.Use of less expensive and more readily maintainable general-purpose electric equipmentenclosures, where appropriate.
cPrevention of access by unauthorized people.
3.2 Maintenance, testing, and safety
Maintenance, testing, and safety of an operating plant must be considered primary factors in the design ofany electrical system.