IEEE 693-2005 pdf free download – IEEE Recommended Practice for Seismic Design of Substations.
1.5.1 Acceptance of previous versions of IEEE Std 693 Equipment qualified to IEEE Std 693-1997 or later versions will be deemed to be in conformance with the current version of IEEE Std 693, and the qualification need not be repeated, unless a previous qualification test or analysis method is explicitly excluded by the current version. The qualification will be acceptable once the explicitly excluded part is done according to the current recommended practice and found acceptable according to A.5 or A.6. Additional documentation will be required if the current version requires additional documentation.
For a manufacturer to use a qualification from a previous edition of this recommended practice to qualify the equipment to the current version of this recommended practice, a supplemental report must be appended to the old qualification report explaining how sections excluded in the new version of the recommended practice will meet the adequacy criteria given in 1.5. The identification tag for the equipment supplied to that user can state that the equipment has been qualified to the current IEEE Std 693.
1.6 Earthquakes and substations Earthquakes are caused by the sudden rupture of a geologic fault. Shock waves radiate from the fault fracture zone and arrive at the earth’s surface as a complex multifrequency vibratory ground motion, having both horizontal and vertical components. The response of buildings and structures to earthquake ground motion depends on factors, including their configuration, strength of construction, ductility, and their dynamic properties. Lightly damped structures having one or more natural modes of oscillation within the frequency band of ground excitation can experience considerable amplification of the forces, component stresses, and deflections. Mechanisms that absorb energy in a structure, in response to its deformation, provide damping. If two or more structures or equipment are linked together, such as through a conductor, they may interact with one another producing a modified response and interaction loads. Even when the link is sufficiently flexible to accommodate the relative displacement, forces may be transferred between the structures or equipment including dynamic effects. Therefore, particular care should be given to that design aspect so that the level of forces is minimized. However, provisions should also be taken in equipment design to take such forces into account. (See 5.9 and IEEE Std 1527-2006 [B23].) In particular, many items of substation equipment, for electrical reasons, are highly interconnected and often contain brittle, relatively low strength (compared with, e.g., steels), and/or low damping materials (e.g., porcelain). The conductors are often installed with very small slack. In these cases, after only a little relative motion occurs, damaging nonlinear interaction, including impacting between connected equipment will begin. Thus, items of substation equipment whose natural frequencies lie in the normal frequency range of earthquake ground motion are particularly vulnerable to damage by seismic events.
1.7 Design and construction It is recognized that a substation may not always be designed and constructed solely by a utility using its in- house expertise. A substation may be designed as a “turnkey contract.” In between these two extremes lie many hybrid possibilities, including the involvement of consultants or architect-engineers as third parties. After the substation is complete, the user should have procedures that ensure that the installed configuration and any subsequent modification or expansion of the substation is subject to proper review to verify that the intentions of this recommended practice are preserved.IEEE 693 pdf download.