IEEE 1268-2005 pdf download IEEE Guide for Safety in the Installation of Mobile Substation Equipment
3.11 transferred voltage: A special case of the touch voltage where a voltage is transferred into or out othe substation fromm or to a remote point external to the substation site.
4.Electrical clearances
4.1 General
Guarding and clearances to energized parts are given in Rule 124 of the 2002 National Electrical SafetyCode (NESC). Clearances to energized parts for safety of personnel are given in Table 124-1 “Clearancesfrom Live Parts” of the 2002 NESC unless adequate insulation or suitable barriers are provided. Rule124A3 of the 2002 NESC states a minimum of 2.6 m between any ungrounded part or parts ofindeterminate potential and any permanent supporting surface where workers might stand. Temporarystructures might be required to maintain proper clearances.
The following 4.2 and 4.3 refer to the clearances for those temporary connections required to install themobile. These clearances will not be tested and therefore need to follow the requirements of the NECANSI C37.32-2002,etc. Tested devices such as the mobile substation (if tested) with its permanentlyinstalled equipment may have clearances that are less than those of the temporary connections required tcplace the mobile in service.
4.2 Phase-to-ground clearances
ANSI C37.32-2002 lists recommended and minimum clearances of energized parts to grounded parts inTable 3, Column 4, and Column 5, respectively. Where applicable, refer to Table 710-33 of the 2005 NEC.
4.3 Phase-to-phase clearances
Minimum metal-to-metal clearances between all disconnecting switches, bus supports, and rigid conductorsare given in Table 5, Column 3, of ANSI C37.32-2002. Distances between nonrigid parts can be adjusted toprovide such minimum clearances. Recommended centerline-to-centerline phase spacing for switches isgiven in Table 5, Column 6, Column 7, and Column 8 of ANSI C37.32-2002. Where applicable, refer toTable 710-33 of the 2005 NEC
5.Grounding
5.1 General
IEEE Std 80 provides general and specific guidelines for grounding substations and can be applied tomobile substation equipment. This clause is intended to discuss specific items that need special emphasis orspecial treatment
Mobile substations or transformer trailers might be installed in many locations.The trailers might beinstalled on utility property or non-utility property. On utility property, the mobile substation might beinstalled inside or outside the permanent substation fence.The mobile substation located outside thepermanent substation fence ight be located next to the substation, a distance away fromm the substation, onthe transmission line right-of-way, or on non-utility property. When the mobile substation is located outsidethe substation fence or on non-utility property, special attention needs to be given to the touch and stepvoltages at the mobile substation fence because it is the most likely point of contact by non-utilitpersonnel, Transferred potential rise between the mobile (and its fencing, if applicable) and the substationneeds to be managed
IEEE 1268-2005 pdf download
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