IEC TS 61463 pdf download – Bushings – Seismic qualification

IEC TS 61463 pdf download – Bushings – Seismic qualification

IEC TS 61463 pdf download – Bushings – Seismic qualification
This technical specification is applicable to alternating current and direct current bushings forrated voltages above 52 kV,mounted on transformers,other apparatus or buildings. lt isaccepted that for bushings for rated voltages less than or equal to 52 kV, due to theircharacteristics (resonance frequency greater than 25 Hz) seismic qualification is not required.
This technical specification presents acceptable seismic qualification methods and require-ments to demonstrate that a bushing can maintain its mechanical properties, insulate and carrycurrent during and after an earthquake.
The seismic qualification of a bushing is only performed upon request.
2Normative references
The following normative documents contain provisions which,through reference in this textconstitute provisions of this technical specification.At the time of publication, the editionsindicated were valid. All normative documents are subject to revision,and parties toagreements based on this technical specification are encouraged to investigate the possibilityof applying the most recent editions of the normative documents indicated below. Members ofIEC and lso maintain registers of currently valid International Standards.
IEC 60068-2-6:1995,Environmental testing – Part 2:Tests -Test Fc: Vibration (sinusoidal)
IEC 60068-2-47:1982,Basic environmental testing procedures – Part 2:Tests – Mounting ofcomponents, equipment and other articles for dynamic tests including shock (Ea), bump (Eb),vibration (Fc and Fd) and steady-state acceleration (Ga) and guidance
IEC 60068-2-57:1989,Environmental testing – Part 2: Test methods – Test Ff: Vibration -Time-history method
IEC 60068-2-59:1990,Environmental testing – Part 2:Test methods – Test Fe:Vibration – Sine-beat method
IEC 60068-3-3:1991,Environmental testing – Part 3: Guidance – Seismic test methods forequipments
IEC 60137:1995,Insulated bushings for alternating voltages above 1 000 v
IEC 60721-2-6:1990,Classification of environmental conditions – Part 2: Environmentalconditions appearing in nature – Earthquake vibration and shock
IEC 61166:1993,High-voltage alternating current circuit-breakers – Guide for seismicqualification of high-voltage alternating current circuit-breakers
IEC 61264:1994,Ceramic pressurized hollow insulators for high-voltage switchgear andcontrolgear
IsO 2041:1990,Vibration and shock – Vocabulary
For the purpose of this technical specification the definitions of lEC 60068-3-3 and lSO 2041,and the following definitions apply:
critical cross-section
section of the bushing that is most likely to fail during an earthquake
response spectrum
plot of the maximum response to a defined input motion of a family of single-degree-of-freedom bodies at a specified damping ratio (Iso 2041,modified)
rigid equipment
equipment whose natural frequency is greater than 25 Hz is considered rigid for the purpose ofthis technical specification
4Symbols and abbreviations
bgEquivalent maximum acceleration to the centre of gravity of the bushing during the
seismic event
Maximum acceleration of the bushing flange
Maximum acceleration of the ground resulting from the motion of a given earthquake
NOTE- ag is equal to the Zero Periad Acceleration (ZPA) of tigure 1.
Distance between the centre of gravity of the part of the bushing which is under
consideration and the critical cross-section
First natural frequeney of the mounted bushing
KSuperelevation factor between ground and bushing flange: factor accounting for the
change in the acceleration from the ground to the flange due to the amplification bybuildings and structures
mp Mass of the part of the bushing which is under consideration
M Bending moment at the critical cross-section of the part of the bushing considered, due
to an earthquake
Response factor derived from the Required Response Spectrum (RRS) as the ratiobetween the response acceleration and the ZPA (see figure 2)
RRS Required Response Spectrum: response spectrum specified by the user
s Coefficient established to take into account the effects of both multifrequency excitation
and multimode response
ZPA Zero Period Acceleration (see ag)
5 Methods of seismic qualification
Seismic qualification should demonstrate the ability of a bushing to withstand seismic stressesand to maintain its required function without failure,during and after an earthquake of aspecified severity iclause 6y.