IEEE Std 693:2018 pdf free download – IEEE Recommended Practice for Seismic Design of Substations
performance level: The level of shaking or seismic event at which qualified equipment is anticipated toperform acceptably with little or no significant structural damage.
performance level response spectrum: A response spectrum that directly reflects the accelerationsassociated with the seismic qualification objective (refer to 5.2).
polymer-housed surge arrester: Arrester using polymeric and composite materials for housing.
primary substation structure: In the context of the support of substation electrical equipment, a primarysubstation structure shall be considered to be any other structure not deemed a dedicated support. Primarysubstation structures may also support rigid bus work or conductors.
required response spectrum (RRS): Response spectrum that defines the required level of input motionfor a given level of qualification.
resonant frequency: Frequencies coinciding with the natural frequency of a system (at which the responseamplitude is a relative maximum) are known as resonance frequencies.At these frequencies, even smallperiodic driving forces can produce large amplitude oscillations.
response spectrum: A plot of the maximum response of an array of single-degree-of-freedom (SDOF)identically damped oscillators with different frequencies, all subjected to the same base excitation.
rigid equipment: Equipment, structures, and components whose lowest resonant frequency is greater than33 Hz on the response spectrum.
seismic identification plate: A physical plate to be placed on the equipment identifying it as havingsatisfied the requirements of this recommended practice. See A.7 for details on the data to be placed on theplate.
seismic outline drawing: A drawing dedicated to the depiction of key seismic qualification parameters ofthe equipment and meeting the requirements of either A.5.5 or A.6.4. See also Annex S and Annex T.
seismic protective device: A device such as a base isolator or damper that reduces seismic response bylowering the frequency and/or increasing the damping to a system.
seismic qualification approach: The solution path for seismic qualification. The two seismic qualificationapproaches used in this recommended practice are the design level approach and the performance levelapproach.
seismic qualification level: There are three levels of qualification, high,moderate, and low.The level atwhich equipment must be qualified is dependent upon the seismicity of the region where it will be inservice.
seismic specialist: An individual who, through education, training, and experience, is capable of planning,performing, and documenting a seismic qualification as described in this recommended practice (A.5.2.A.6.2).
specified cantilever load: As defined in IEC 62231,the cantilever load that a solid core station postcomposite insulator can withstand for a short term.
specified long-term load(SLL): As defined in IEC 60099-4, the force perpendicular to the longitudinalaxis of an arrester，allowed to be continuously applied during service without causing any mechanicaldamage to the arrester.
4.4 Selection of qualification level for a region
This recommended practice provides three levels of qualification that should encompass the needs of mostusers. Experience has shown that it is good practice to specify the same criteria for all like equipment in allsubstations within a reasonably large geographical area. In the event of equipment malfunction followingan earthquake,equipment from other substations or standard spares can be moved and installed in thesubstation that experienced the loss. Equipment inventory management may be simplified by employingthe fewest number of different qualification levels.
When selecting or standardizing a seismic qualification level for a region, the qualification level should bebased on the highest seismicity within the region being considered.Refer to 5.7 and 5.12.