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| Re: PHOTOS: SHOO FLY TWO (1276422) | |||
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Re: PHOTOS: SHOO FLY TWO |
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Posted by Bill West on Thu Feb 20 13:08:33 2014, in response to Re: PHOTOS: SHOO FLY TWO, posted by Jersey Mike on Thu Feb 20 09:30:14 2014. PRR breakers -yes, saving the substantial cost of high voltage circuit breakers by switching lines from the low side of the transformer was a smart idea that PRR lead in adopting. There would be lots of line faults that could be cleared from the high or low side but only a few transformer faults that would need clearing from the high side. So omitting the high side breaker and momentarily taking the whole line out for those cases would be sufficient. This is the same as the way that main circuit breakers on EMUs were replaced by pantograph grounding switches and opening of the cat circuit breaker back at the substation. Our western utilities did the same thing with smaller substations on 60 & 138kv transmission routes complete with a spring operated grounding switch to signal the need to trip back to the source substation.I think you know that originally the only 132kv breakers on the PRR were at Zoo, Perryville and Thorndale. I find them a novelty because they are 2 pole instead of the 3 that every other transmission breaker in the country is. And also because they have survived for 80 years, one doesn't see many higher voltage bulk oil circuit breakers any more. Nowadays Amtrak has included 132kv breakers at Jericho Park and indoors at Richmond SFC. Bill |
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