1200 kV breaker for R phase designed for 2400 kV lightning impulse withstand, 1800 kV switching impulse withstand, 5000 A normal current and 50 kA breaking current.
In the case of the new Bina facility, the investment was shared by the publically owned grid operator as well as a consortium that now numbers some 35 indigenous suppliers of electrical equipment and components. While PowerGrid provided the test bed for the field trials, all equipment was internally developed and financed by these individual suppliers. The goal behind this partnership was to promote rapid development of domestic expertise in UHV, especially in light of the fact that there are still no international standards to rely on.
One of the interesting features in building the test circuits at Bina was that construction techniques and equipment used for tower erection and stringing had to replicate, as much as possible, what would reasonably be available to crews in the field – even across the more remote areas of the country. The test station’ s circa one kilometer single circuit and double circuit lines will also provide Indian engineers with valuable information on operational and safety requirements at such a UHV level.
Among the more notable features of the technology now in place at Bina is that it was apparently developed from system studies at 1200 kV and not based on simply extrapolating parameters from existing 400 kV / 765 kV networks. Moreover, the decision to go with an operating voltage of 1150 kV versus the 1000 kV level selected by engineers in China was to obtain higher power transfer capabilities while keeping basically the same switching and lightning impulse insulation levels using high performance, multi-column surge arresters. The somewhat reduced insulation level margin would then be offset by gains in optimizing cost and sizing of associated equipment, the latter especially important given limitations in transport infrastructure.
In order to best allow comparative assessment of performance, much of the equipment such as the 1200 kV single-phase transformers, capacitive voltage transformers and polymeric surge arresters involve a different supplier for each phase. This applies as well to the 1200 kV circuit breakers, one of which utilizes two-column composite housed bushings while the other is designed with huge onepiece composite housings.
Second phase charging of the test station is currently scheduled for August of next year. �
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