NStar major failure with no plan
posted at 3/18/2012 6:54 PM EDTWhile we can beatup on the response due to weather with good reason. Why cannot NStar design a system to respond to point failure. These are much more predictable than the weather. The zone of the effect was known before the original transformer was installed. Thus the area of impact was predictable. This was not an accident but delibrate negligence. A failure to treat failure seriously. I expect some serious legal settlements due to negligence when providing a public utility.
NStar distribution problems
posted at 3/19/2012 9:15 AM EDT
NStar responded reasonably well to the Scotia St. substation fire and was able to replace a major transformer promptly. Its key problem was not in responding to the incident but in preventing it.
There have been no useful news reports so far on the Scotia St. incident, with the Herald only slightly more informative than the Globe. It took Globe reporters two days just to describe the boundaries, when a stroll around the area the evening it began would have done the job quite well. The Herald but not the Globe reported that the failed transformer was a three-phase 115/14 kV installed in 1973.
The Scotia St. substation is a major interconnect in the Boston Edison system, with two 115 kV lines (329-512 and 385-513) to Brighton and to Carver St. The lines serving Scotia St. have emergency ratings of 260 MVA to Brighton and 285 MVA to Carver St. Contrary to impressions left by reporters, those lines are fairly new. They were replaced at a cost of over $5 million during the 1,000 MVA, 345 kV transmission project connecting Stoughton to South Boston, completed in 2007, carrying some of the power from Exelon's 688 MW combined-cycle, natural gas-fired generators at the former Edgar Station site in Weymouth.
[ Press release, NSTAR energizes major underground transmission line, NStar, May 3, 2007, at http://www.nstar.com/ss3/nstar_news/press_releases/2007/345kv.asp and ISO New England reports, at http://www.iso-ne.com/committees/comm_wkgrps/relblty_comm/relblty/mtrls/2003/apr82003/A5-3_mys184aps.doc and http://www.iso-ne.com/committees/comm_wkgrps/relblty_comm/relblty/mtrls/2004/aug312004/A9-1_NSTAR 345 Project Schedule 12C Application Addendum.doc ]
The early 1970s transformers typically used askarels, but none of the stupid reporters so far mentions the status of the transformer that failed or appears aware of the potential hazard. Some such units have been refitted with Midel, MODF and other fluids, but remnants of PCBs may contaminate replacement fluids. Most likely, the Back Bay of Boston was drenched in polychlorinated biphenyls.
Smaller transformers of that vintage in our neighborhood, mostly feeder stepdowns to 4.16 kV distribution, failed frequently until a major upgrade to 13.8 kV distribution a few years ago. As with the Scotia St. failure, many outages started at transformer connectors. We found that NStar had no readily retrievable records of failures extending over several years and had been routinely overloading its transformers as distribution loads gradually grew over the years.