Testing and contribution to the certification of power plant and transmission components

After the Northridge (1994) earthquakes, during which power transmission installations were destroyed at the Sylmar (nuclear) power plant, the Los Angeles - California power company (LADWP) decided the upgrading of its earthquake resistance. Following an international contest, the research-design, construction and certification project was undertaken by ABB, a company based in Sweden with several branches in various countries. Next, a group of ABB engineers toured the laboratories with dynamic seismic testing facilities around the world, a tour which resulted in the selection of the Laboratory for Earthquake Engineering (LEE) of the NTUA for future collaboration. The particular collaboration started in 1998; meanwhile, through the same firm, ABB, seismic tests have also been carried out for the power companies of Chile and El Salvador. The very high seismicity of all three areas is well known and so are the very high earthquake resistant standards that must be met by the respective power transmission and distribution installations. Each test was carried out in the presence of the responsible research engineers of ABB and the respective representatives of the owners (Los Angeles, Chile, El Salvador) as well as of specialist auditing engineers from insurance companies selected by the owners. It is clear that each concerned party expected perfect execution of the testing according to state-of-the-art technology, international standards and any additional requirements which might arise during the execution of the tests. It follows from the continuation of the above collaboration that the quality of the work is absolutely satisfactory and that the LEE of the NTUA is successfully competing with similar laboratories of other countries. At this point it is worth mentioning that the LEE has been asked to repeat tests which were originally executed in well known respective foreign laboratories but failed to meet the required standards. The testing procedure followed is consistent with and almost identical to standard IEEE 693-1997 "Recommended Practices for Seismic Design of Substations", IEEE Power Energy Society (1998). Particularly: initially, static tests are performed aiming at the calibration of strain gauges which monitor moment or displacement. Next, a static deflection test, from the resting position of the specimen, and a recording of its free vibration is carried out for the calculation of its natural period of vibration, damping as well as stiffness. Then, the specimen is subjected to independent frequency sweeping excitations (0.5 - 35 Hz) with stable acceleration, usually 0.05 g, in every main direction of its geometry to determine its dynamic properties. Next, it undergoes a triaxial seismic excitation at the desired seismic intensity level and, finally, it is subjected to five beats (composite vibrations) of 10 cycles each at its resonance frequency.

ΑΒΒ, DC Pole Bushing Type GGFL 1300 -1200 - 3150, LADWP /Los Angeles, December 2003.
Polymer-Bushing Type SETFta 900 - 230 - 3000 Spez (HSP) mounted on flexible steel turret for converter transformer, Los Angeles, November 2003.	ΑΒΒ HVDC, Coverter Transformer Bushing Type GGF 1550 -1290 - 3000, LADWP /Los Angeles, April 2003.
ABB Current Transformer IMB 145, January 2003.	ABB SF6 Circuit Breaker HPL 550 TB4 with operating mechanism BLG 1002 A . , November 2001.
ABB SF 6 Circuit Breaker HPL 550 B 3 with operating mechanism BLG 1002 A and dampers, November 2001.	ABB 3-Phase Circuit Breaker LTB 145/ D 1 with current transformer IMB 145, July 2001.
ABB 3-Phase Circuit Breaker LTB 145/ D 1, July 2001.	ABB Current Transformer IMB 245 with dampers for Chile, December 2000.
ABB Current Transformer IMB 245 for Chile, September 2000.	Circuit Breaker HPL 550 with dampers, El Salvador, April 1999.
ABB Optical Current Tranducer of high voltage DC for Sylmar station PIU / LADWP,California, October 1998.	ABB Transformer Bushing for Sylmar station PIU / LADWP , Los Angeles, May 1998.
ALSTOM Current Transformer CTH 765 kV, June 2003.	Siemens, Circuit Breaker Type 3AQ 2 I - 420 kV , September 1993.
Assesment of vulnerability of breakers and circut breaker - ΔΕΗ, 1996