W210-12063
Version 1.0, July 23 , 2012
Three-Phase and Substation Class
Transformer Seismic Qualification
Shaun Kologinczak
Sr. Product Specialist –Substation Transformers
Jack Moore
Global Product Manager: Three-Phase Pad-Mounted Transformers, Substation Transformers, and MITS
Cooper Power Systems
2300 Badger Drive
Waukesha, WI 53188
one cooper – online
P: 877.CPS.INFO
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2011 Transformer Seismic Qualification
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Table of Contents
1.
Executive Summary .......................................................................................... 3
2.
Who Is OSHPD? ....................................................................................................3
3.
What Does it Mean to You? .................................................................................3
4.
What are the Requirements?............................................................................ 4
5.
The Testing Process ........................................................................................ 5
6.
Quantifying SDS ................................................................................................ 6
7.
Comparing Richter Scale to SDS ..................................................................... 8
8.
Conclusion......................................................................................................... 9
9.
Appendix .......................................................................................................... 10
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1. Executive Summary
With the ever increasing focus on safety and risk mitigation, California has taken additional
steps toward setting higher building standards. With the introduction of the California Building
Code (CBC) 2010, California has increased the seismic requirements for facilities that are
considered to be supplying general acute care. In the case of a hospital, one of the core
dependencies for functionality of the building is power. A transformer, under CBC 2010,
powering a building is considered critical equipment needed to sustain its functionality after a
seismic event. This requirement is not only relevant and necessary in the California Healthcare
arena, but anywhere a critical load is present – to ensure uninterrupted service. Cooper Power
Systems has proactively attained the Office of Statewide Health Planning and Development
(OSHPD) certification for liquid-filled transformers ranging from 45 kVa –10,000 kVa. If a facility
supports critical loads such as ─ hospitals, data centers, and production facilities ─ securing
transformers certified to handle significant seismic activity and mitigate the opportunity for
downtime or interruption is imperative.
2. Who is OSHPD?
The Office of Statewide Health Planning and Development is one of thirteen departments within
the California Health and Human Services Agency. OSHPD administers programs which
endeavor to implement the vision of "Equitable Healthcare Accessibility for California."
Currently, OSHPD regulates all healthcare projects in California, specifically focused on seismic
requirements. The organization has significant influence over worldwide seismic standards and
the International Building Code (IBC) as California is viewed as a leader in seismic standards.
The intent of the code is to provide reasonable assurance of seismic performance to avoid
serious injury and loss of life, loss of function in critical facilities, and minimize repair cost.
The OSHPD Anchorage Preapproval (OPA) and OSHPD Special Seismic Certification
Preapproval (OSP) Programs operate under the SB 1953 Seismic Retrofit Program within the
Facilities Development Division (FDD). These Programs review and pre-approve, as warranted,
anchorage and special seismic certification of equipment and components to be used in health
facility construction.
3. What do the OSHPD Requirements Mean to a Specifying Engineer, Owner,
or Operator?
OSHPD has deemed that critical equipment, such as transformers, are required to meet seismic
testing qualifications. This requirement will provide reasonable assurance that the product’s
performance will:
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Avoid serious injury and life loss.
Avoid loss of function in critical facilities.
Minimize structural and nonstructural repair costs where practical to do so.
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Health care facilities or new construction projects that fall under the new OSHPD criteria, along
with other critical load owners/operators, should specify an OSHPD-certified manufacturer.
Certified manufacturers are identified by their OSHPD issued OSP number. Cooper Power
Systems is identified by OSP-0121-10, and all specifying engineers, owners, and operators
should request this number when specifying transformers at the time of bid.
Other applications (besides health care facilities) that would improve risk mitigation by
specifying equipment to OSHPD requirements:
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•
•
•
•
•
Data centers
Educational facilities
Waste water treatment
Refineries
Petrochemical
Other process industries
4. Requirements for OSP and OPA Certification
Under CBC 2010 there are specific requirements for different product categories which would
be installed into a health care facility (hospital, acute care, long-term healthcare, surgical
centers, etc). For products essential to the functionality of these facilities, as in the case of an
electrical transformer, the standards are the most stringent. CBC 2010 Section 1708A.4
requires certification of the product, and once completed and approved, is identified via the OSP
number. Its anchoring design would then be reviewed and certified by a licensed California
structural engineer and submitted to OSHPD. Upon approval, a number will be issued for the
anchoring design. Typically the contractor or engineer would need to get this certification on a
case-by-case, project-by-project scenario. Cooper Power Systems has pre-qualified the
necessary anchoring methods for these transformers, thereby eliminating coordination efforts
needed in the field.
OSP Testing Requirements
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Testing of at least two units (typically the smallest and largest units), and Verification of
similarities for interpolated units (CBC 2010 Section 1708A.4).
All components shall be designed in accordance with the CBC requirements.
Testing laboratory shall have ISO 17025 accreditation, or testing shall be under the
responsible charge of an independent California licensed engineer.
Test reports shall be prepared by a California licensed engineer, and test reports shall
be reviewed and accepted by an independent California licensed structural engineer,
unless it is prepared by one.
Post-test acceptance criteria for shake-table testing shall be as required by
ICC-ES AC 156:
o Structural integrity of components, supports, and attachments shall be
maintained.
o Functionality of components shall be maintained.
2011 Transformer Seismic Qualification
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OSHPD strongly recommends that a manufacturer’s representative and Californialicensed structural engineer in responsible charge for the OSP meet with OSHPD to
review:
o Scope of the OSP
o Test plan that will justify the scope of OSP
o Test standard and reporting requirements
o Seismic Certification Label requirements
Functionality test shall be as required by ICC-ES AC 156: Functionality test shall be
similar to what the manufacturer normally performs prior to shipping the
equipment/components for use.
A list of qualified manufacturers is available at:
http://www.oshpd.ca.gov/FDD/Pre-Approval/special_seismic_cert_pre-approval.html
5. How Does the Testing Process Take Place?
The testing process is completed on shaker tables that are capable of simulating a wide range
of ground motions – including earthquakes. Modern shaker tables are driven by actuators of
various designs and are able to simulate motion in as many as six degrees of freedom. The
equipment that is tested is specifically chosen to represent a broad product scope. Typically, a
small unit and a large unit are chosen to provide this breadth of scope. During the testing
process the tables simulate forces that are relative to the resonant frequency of the three axis of
the transformer as well as to the SDS (design spectral response acceleration) that has been
chosen.
http://www.oeashrae.org/Presentations/2011_12/Special_Seismic_Certification_ASHRAE_Presentation.pdf
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6. Quantifying the Certification
To achieve seismic certification, a manufacturer must demonstrate its product is able to
withstand the SDS criteria for the qualification they are seeking. Product can then only be applied
to areas that have the equivalent or lesser of an SDS level qualification. Details of the testing
requirements are outlined below.
Defining SDS
SDS = Design, 5% damped, spectral response acceleration parameter at short periods
Ss = Mapped maximum-considered earthquake, 5% damped, spectral response acceleration
parameter at short periods
Fa = Site coefficient, this is a value between 0.8 and 2.5 and is chosen from a table based on
the site class and spectral acceleration (Ss)
SDS 1 is defined by the following equation: SDS = Ss x Fa x 2/3
1
Note: SS and SDS are both identified as a % of gravity.
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The steps to determine the SDS level for a specific site are as follows:
Ss - First, the spectral response acceleration of the construction location must be determined.
This can be found on the contour drawing in ASCE 7 or also with a downloadable application
offered by the USGS (United States Geological Survey) website 2 – determined by latitude and
longitudinal coordinates, or by zip code.
The second determination is the site class 3 for the construction location. This is indicated by a
letter A-F, where A is hard rock and least affected by seismic activity, to F which is high
plasticity clay or peat soil, which is more likely to be affected. This step can typically be
completed or assisted by a geologist or civil engineering expert.
Fa - The third and final step to determine your site’s SDS level is to determine the site
coefficient. This is a value between 0.8 and 2.5 and is chosen from a table based on the site
class (A-F) and spectral acceleration (Ss). This information can also be found in ASCE 7.
Figure 1. ASCE/SEI 7-05
Example
SS = 1.656, Site class = B, therefore Fa = 1.0
SDS = 1.656 x 1.0 x 2/3 = 1.104
2
3
http://earthquake.usgs.gov/hazards/designmaps/javacalc.php
IBC, ASCE 7-02 & 7-05 - Appendix
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To assist in estimating some of these values at a specific site, the USGS tool can estimate by
coordinates or by zip code (Ss values would be given the site classifications). This tool can also
estimate the SDS level that corresponds to that site as a means of attaining a quick reference
value. 4 See Figure 2 for details.
Figure 2
http://earthquake.usgs.gov/hazards/designmaps/javacalc.php
7. Comparing the Richter Scale to SDS (Richter = Energy, SDS = Ground
Acceleration)
Questions may exist relative to how these standards and values relate to the more common
Richter scale, or relate to more recent and well-known seismic occurrences. Unlike earlier
values that measure acceleration, the Richter scale measures energy released by an
earthquake via a logarithmic scale. For each whole number increase the amplitude increases
ten-fold while the energy released is 31 times that of the previous number. In contrast the peak
ground acceleration (PGA) is the measure of the surface ground motion, which will decrease the
further from the earthquake you are located. To provide a point of reference, the 1964 Alaskan
earthquake had a magnitude of 9.2 with an estimated PGA of 0.18g while the 2011 Japan
4
This is a reference tool to approximate the seismic factors
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earthquake had a magnitude of 9.0 with a PGA estimated at 0.4g. Thus, similar magnitudes can
result in dramatically different ground accelerations.
The relationship between PGA and SDS is estimated by the equation of SDS = 2.5 x PGA. With
that approximation the Japanese earthquake would have been in the range of an SDS level of
1.0. Using this as a reference point, Cooper Power Systems has qualified subject equipment to
an SDS level of 1.93 which is significantly higher than even the levels recorded during the 2011
Japanese earthquake.
8. Conclusion/Summary
Cooper Power Systems is committed to providing products that meet and exceed the needs of
its customers and provide the secure distribution of electricity to sensitive industries in seismicprone areas. Cooper Power Systems has designed, tested, and built transformers that meet the
OSHPD standards of seismic safety. Three-phase transformers with ratings from 45 kVa to
10,000 kVa, as outlined by the OSHPD OSP-0121-012, are capable of withstanding a seismic
level equivalent of SDS 1.93. This provides a margin of safety that is acceptable in most all areas
of the landmass in the Continental United States. Below is a graphical representation of the
typical frequency of occurrence of a magnitude 5 or larger per year. It can be concluded from
this information that the use of transformers certified to OSPD OSP-0121-012 requirements
would be of benefit to locations other than the state of California, especially for critical load
applications such as hospitals, data centers, and production facilities.
http://earthquake.usgs.gov/earthquakes/states/us_density.php
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9. Appendix
CBC 2010 Section 1708A.4
The manufacturer of each designated seismic system component subject to the provisions of
ASCE 7 Section 13.2.2 shall test or analyze the component and its mounting system or
anchorage and submit a certificate of compliance for review and acceptance by the registered
design professional responsible for the design of the designated seismic system and for
approval by the building official.
Certification shall be based on: An actual test on a shake table, by three-dimensional shock
tests, by an analytical method using dynamic characteristics and forces, by the use of
experience data (i.e., historical data demonstrating acceptable seismic performance), or by
more rigorous analysis providing for equivalent safety.
2011 Transformer Seismic Qualification
For complete details, visit:
http://www.oshpd.ca.gov/FDD/Pre-Approval/OSP-0121-10.pdf
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2011 Transformer Seismic Qualification
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The information contained in this document was provided to you by Cooper Power Systems for
the purpose of better understanding of Cooper Power Systems three-phase and substation
class transformer seismic qualification. Should you have questions or concerns regarding the
information within this white paper—Cooper Power Systems invites you to contact the Authors.
Authors:
Shaun Kologinczak
Sr. Product Specialist – Substation Transformers
P: 262-524-3459
E: Shaun.Kologinczak@cooperindustries.com
Jack Moore
Global Product Manager
P: 262-524-4402
E: Jack.Moore@cooperindustries.com
Solution Area Expert:
Michael Loomans
Engineering Manager
P: 262-524-3265
E: Michael.Loomans@cooperindustries.com
877.CPS.INFO
One Cooper │www.cooperpower.com│Online