Project Title/ID Number Seismic Qualification and Fragility Testing of 500kV Disconnect Switches—Lifelines 411
Start/End Dates 10/1/02—9/30/03
Project Leader Gregory Fenves (UCB/Faculty)
Team Members Shakhzod Takhirov (UCB/Other), Don Clyde (UCB/Other)
Project goals and objectives

Project 411 consisted of seismic qualification and fragility testing of 500kV disconnect switch. Qualification by shake table testing is intended to demonstrate that the disconnect switch and appurtenant equipment satisfy the requirements of IEEE 693-1997 at the high qualification level. Tests at two RRS levels (0.25g, pga and 0.5g, pga), the Performance Level (1.0g, pga), and fragility tests are included in the test program.

Role of this project in supporting PEER’s vision

Assessment of seismic vulnerability of high voltage substation equipment and development of seismically reinforced designs.

Methodology employed

Testing will be performed on a single pole, 550kV, 4000A, Model “EV-1” switch, with ground switch and motor operator, manufactured by Southern States, Inc. (SS). The test program will include up to three types of insulator mountings in the switch, one standard with adjustable bolts and two seismically reinforced ones that include (among other modifications) using a more rigid shimmed mounting or a thicker base plates with large size leveling bolts. The seismic mounting will be tested in the case when the possible failure of the standard design will be obviously unavoidable at higher levels of testing. The possibility of the failure will be estimated at random strong motion time history testing at 0.25g pga. The switch will be tested mounted on the elevated support tubes: full-length supports commonly used in field mounting by the utilities and shorten supports to explore a possibility to model the full-length supports by equivalent shorten-supports. A photo of the assembled test specimen on full-length supports ready for the test is presented in Fig. 1 (the height of the switch structure with main blade closed is about 34’). The switch will be tested rigidly mounted to the earthquake simulation platform to qualify the switch with the main blade in open position, in this case the highest point of the switch will be at about 37’ from the earthquake simulator platform.

Strong Motion Input Signals

Switch Assemblies will be tested to identify switch dynamic characteristics using resonance search, low-level static test, and random input motion tests. Random strong motion signals are modified from an actual earthquake record to comply with IEEE-693 (1997) requirements and they envelope the corresponding required response spectra. Target spectral acceleration of the vertical component of the three-dimensional random motion is taken at 80% of a horizontal value. The input duration of the time history is more than 20 s of strong motion as it is required by the IEEE-693 (1997) document. The random input strong motions are filtered to accommodate the capacity limitations of the earthquake simulation platform.


Figure 1. 500 kV disconnect switch on the full-length supports

Larger View

Two input signals of strong motion time histories will be used for testing. The first signal is intended for testing at 0.25g ad 0.5g. The second signal is delivered for the testing at the Performance Level for 1.0g pga. Both signals are filtered from the same strong motion time history enveloping the IEEE spectra, the first required less filtering in low frequency range than the second one.
Brief description of past year’s accomplishments and more detail on expected Year 6 accomplishments

All preparation tasks have been accomplished: the specimen has been assembled, the specimen has been extensively instrumented, and random time history for earthquake simulator has been developed.

Other similar work being conducted within and outside PEER and how this project differs

Task 408 delivered the random time history based on analysis of 30 earthquake records.

Plans for Year 7 if this project is expected to be continued

The project is scheduled to be completed by July 2003.

Describe any instances where you are aware that your results have been used in industry

Based on the test results the utilities will continue to use and install standard design of the 500 kV disconnect switch or will consume switches with seismically reinforced design.

Expected milestones

Test starts in April 2003 and should be accomplished with a month. The report preparation and data reduction will be conducted after the test.


Assessment of seismic vulnerability of 500 kV disconnect switch with standard and seismically reinforced designs; qualification test of the switch to comply to the requirement of the IEEE-693 (1997)