Tips & News - April 2013

seismic capabilities

Hubbell Power Systems is committed to providing enduring products – even in the most demanding environments. We provide multiple product lines suitable for high seismic conditions.

PCORE ® Bushings PCORE adheres to the rigorous testing standards and strives to provide the most comprehensive selection of 15kV through 500kV porcelain bushings available to address the electric industry’s seismic needs. PCORE offers a wide range of products, including 15kV-69kV PRC ® (Paper-Resin-Capacitor) bushings, 25kV-500kV POC ® (Paper-Oil-Capacitor) bushings and cost-saving products such SET-Terminals, Bushing Repair and the patented Quick-Link bushing. PRC & POC To meet the IEEE 693-2005 testing requirements, PCORE conducted the highest level of the time history shake-table test on a 500kV-1675kV BIL POC Series II Bushing. The bushing successfully passed the test and exceeded the 2g requirements by 25%making PCORE the first porcelain bushing manufacturer in the world to offer such a strong, seismically-approved design. The IEEE standard allows qualifying equipment by group where PCORE 115kV to 500kV Series II bushings are structurally similar and therefore are also certified to the highest seismic performance level. PCORE 15kV to 138kV bushings are qualified by the static pull tests as defined by the IEEE 693-2005 standard. SET-Terminals The new and improved SET-Terminal is used for faster, safer & more cost effective dielectric testing. The SET-Terminal has a rated static cantilever strength of up to 2500 ft-lbs, more than 300% higher than existing models and can absorb high shock loading in excess of 500g’s with side blades in the open position.

AVR 245kV Switch The USCO ® AVR 230kV 3000Amp Vertical Break Switch meets the IEEE 693 standards for high seismic qualifications. During testing, this switch operated flawlessly even after two rounds of open blade testing – which appears to be a fi rst for group operated switches. Its robust construction, coupled with simple design concepts, provide ease of operation in even the most stressful environments. The AVR group operated air break switch carries a 10 year warranty - the longest in the industry - and is an appropriate, cost-eff ective choice for substations that reside in a seismic-prone region.

performance Qualification Levels

Seismic Qualification Levels

IEEE 693 Qualification Level

Ground Acceleration gs

Response Acceleration gs

IEEE 693 Qualification Level

Ground Acceleration gs

Response Acceleration gs

Qualification Tests for PCORE ® Bushings Time History Shake-Table Test

Low

0.1

0.2

High

0.5

1.6

In 2012, PCORE conducted the highest level of the time history shake-table test on a 500kV POC Series II bushing. During the test, the bushing was shaken at an acceleration of 2.5g (25% higher than the required value of 2g) and the top of the bushing experienced an acceleration of more than 8g. The bushing passed the test which was witnessed and certified by a California-licensed professional engineer. In 2001, PCORE conducted the highest level of the time history shake-table test on a 345kV POC Series II bushing. During the test, the bushing was shaken at an acceleration of 2g and the top of the bushing experienced an acceleration of more than 6g. The bushing passed the test which was witnessed and certified by a California-licensed professional engineer. As IEEE 693 allows “qualifying equipment by group” in 4.7 and PCORE 115 kV to 500 kV POC Series II bushings are structurally similar, all PCORE 115 kV to 500 kV POC Series II bushings are certified to the highest seismic performance level. Static Pull Test PCORE 15kV to 138kV bushings passed the static pull tests. During the test, the applied force is much higher than the required value (which is double bushing weight). This test is also much more stringent than the requirement for the inherently acceptable calculation for 15kV and 25kV bushings. RESULTS All PCORE 15 kV to 138 kV bushings are qualified by the static pull tests. PCORE 115 kV to 500 kV POC Series-II bushings are qualified to the highest performance level by the time history shake-table test.

Moderate

0.25

0.8

Performance

1.0

3.2

MVN Arrester Key parameters affecting the seismic capability of arresters are the grade of porcelain used, the thickness of the housing walls and the overall mass and center of gravity of the arrester. The MVN arrester supersedes the original VN arrester with 40% stronger casting, a redesigned base and reduced overall height, making it the arrester of choice for high seismic regions. To be qualified to the high seismic performance level, IEEE 693-2005 requires that an arrester be tested to the 1.0g ZPA level, survives the shake-table test with no structural damage, and that it remains functional, as demonstrated by successfully passing routine produc tion tests after the shake-table test. These tests consist of measurement of reference voltage, partial discharge and watts loss, and performance of seal-leak tests. RESULTS MVN porcelain ANSI arresters as well as MH3 and MH4 porcelain IEC arresters up to three stacked units are qualified to High Seismic Performance.

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