- About Us
- Areas of Specialization
- FAQ/Technical Resources
Do you only perform seismic analysis on electrical equipment?
No, although we specialize in seismic design of electrical distribution equipment, our strong background in structural analysis allows us to evaluate many different structures. Other examples of this are: analysis of jacking and lifting of large equipment, fatigue loading, thermal loading, and various types of building analysis. We are always open to taking on new and challenging structural analysis projects.
For qualification of large power transformers to IEEE-693-2005, do radiators have to be braced back to the tank?
The need for horizontal and vertical radiator bracing for transformers 115kV and greater is a requirement. The exact language is “e) Requirements for radiators. For radiators of transformers and liquid-filled reactors having a high side of 115 kV and above, horizontal and vertical seismic bracing for the radiator shall be connected directly to the body of the transformer.”
What levels of seismic rating are covered by your standard qualification procedure for OSHPD or IBC certification?
OSHPD will recognize all levels of earthquake rating as long as it meets the requirements of the building design site. We always try to achieve the maximum seismic rating that the equipment could be expected to withstand with a target of the maximum seismic hazard in the US. If qualified to the highest levels (SDS = 2.5) the equipment could be installed anywhere in the US.
Are you familiar with California OSHPD certifications? How does it compare to a standard AC-156 test? What type of building would require equipment to be installed with OSHPD certification?
We are very familiar with OSHPD OSP certification. The process for getting an OSHPD certified product line is more detailed and time consuming than a normal IBC/CBC qualification as the details of the test must be reviewed and approved by OSHPD. OSHPD OSP certification is only required for equipment that is to be installed in California Hospitals.
Is there such a thing as an IBC Certification? If so, can I certify my product line by FE analysis or do I have to have my equipment physically shake table tested?
Yes, we have certified many types of equipment and product lines for IBC compliance. The latest version of the IBC requires that all critical electrical and mechanical equipment (Ip = 1.5) located in Seismic Design Category C through F buildings be seismically certified by shake table testing. For nearly all other cases the certification can be achieved by analysis.
I have a project to be installed in a country besides the United States. Have you ever provided equipment qualifications for international standards? Is this something you can do?
Yes. The method for qualification is dependent on the seismic requirements for that region and often specific requirements of the end user. We have provided qualification to various international specifications. Some examples of Codes that we have provided qualifications for are the EUROCODE EN-1998-1, EN 1998-6, Hydro Quebec TET-APG-N-0001, Transelec Seismic Design ETG-A.0.20, New Zealand Standard NZs1170, Australian Standard AS1170, and the Chilean Code NCh2369.
Can equipment be qualified to IEEE-693-2005 with support conditions unknown?
Yes, per IEEE-693-2005 Annex 5.5.4 equipment can be qualified by shake-table test or analysis with an unknown support conditions, however, a RRS amplification factor of 2.5 is required to account for unknown conditions. Once a support structure is designed the user shall verify that the designed support does not amplify the loading to the equipment more than 2.25 times.
Several of our units are seismically qualified via shake table test to IEEE 693; without a support structure. 100% of these units get mounted on some kind of structure. What is the relationship between the shake table test and the infinite variety of support structures that are out there?
The units should have been tested to the High or Moderate level RRS amplified by 2.5 times to account for the unit being tested off support with support parameters not known. According to IEEE 693, if the test was done properly, the unit is seismically qualified to be mounted on any support. However, according to IEEE 693, it is the end users responsibility to ensure their support stand is designed such that it does not amplify the ground accelerations by more than 2.25 times. This is often verified by dynamic analysis of the support stand or the support stand is simply designed to be inherently stiff to ensure the seismic loading is not amplified.
What information do you need to provide a quotation or proposal for qualification?
In general we need a copy of the customer specification, installation location, and a general outline drawing of the equipment including kV rating, general dimensions, total weight, and anchorage layout.
What are UBC Seismic Zones and how do they relate to current design procedures?
UBC Seismic Zones were used with the seismic design procedures of the Uniform Building Code (UBC). The UBC Seismic Zones are no longer used with current building codes. The last iteration of the UBC was issued in 1997 and since 2000 the International Building Code (IBC) and ASCE 7 have used site specific earthquake hazard data based on ground motion maps provided by the USGS. Rather than large geographical regions covered by a single seismic zone, seismic demands may now be based on the exact location of a project.
The IEEE Std 693 differs from the IBC and ASCE 7 in that the seismic demand is based on a low, moderate, or high seismic level. IEEE Std 693 seismic levels are based on peak ground accelerations derived from the IBC seismic design parameters and do not correspond to UBC Seismic Zones. Refer to Section 8.6 of the IEEE Std 693-2005 to determine the seismic level for a particular site.