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There's also a possibility that these are voltage regulators - automatic transformer-like devices that can either add or subtract an adjustable amount of voltage from the incoming HV mains in order to provide a more regulated source of voltage to downstream loads. Yep! In the event of a phase to ground fault these are designed to open and then automatically reclose after a short time. This allows an arcing fault to clear. If it's a more permanent fault, the recloser will try two more times and then will lock out. Older systems required manual resetting - newer systems (such as the one you saw) can be remotely reset by the dispatcher via an RF link. : You are correct! These are quite common - they're called Power Factor Correction (PFC) capacitors. They are usually rectangular boxes with two or more Frankenstein-like insulators. Many customer loads tend to be inductive in nature - these typically include fluorescent lighting, induction motors, microwave ovens, low voltage transformers, etc. The inductive reactance of these loads tend to cause the current and voltage to get out of phase, which can then lead to excessive heating and voltage drops along the power company's distribution lines. By adding lumped capacitance across the lines, the power company can "correct" for the load's inductive reactance, thereby improving the efficiency of their power distribution system. In some cases the inductive load may not be constant, so the power company may need to switch in the capacitor bank as required. In this case, you'll see can-like instrument/control transformers and high voltage switches in additin to the rectangular PFC capacitors. PFC capacitors also contain bleeder resistors that safely discharge these (over a period of about 5 minutes) so that company personnel can safely work on the system. For more information, see: : My pleasure - best regards, Bert
: Thanks Bert, and happy Independence Day!
:
: I could send you some pictures if you want, but it does sound like these
: are inductors. They are in the same type of cylindrical housing as
: transformers, so a coil of wire would likely be a good fit.
:
: There's other hardware on the poles that have me puzzled, too. One was a
: set of feeds, again in series with all three phases, that went into a
: fairly large rectangular box (total of six terminals). Plenty of other
: wires came and went into that box, down the pole to two cabinets mounted
: three feet from the ground. In addition, a small yagi antenna was bolted
: to the pole about half way up, its feed also going down to one of the two
: cabinets.
:
: The mystery of what all that was about was solved by a sign on the pole
: identifying it as "TIE RECLOSER #XXX." OK, that was an easy one!
: A few poles down from that there's another bunch of poletop hardware, with
: another six terminal rectangular box. This one has a warning sign to the
: linemen to "Service capacitors in accordance with directive
: XXX," and "AVOID INJURIES. Wait five minutes after disconnecting
: capacitors before servicing." OK, I guess this is a capacitor box of
: some type. Maybe they use the capacitors to balance their inductors!
http://en.wikipedia.org/wiki/Power_factor
: Thanks so much for the help, Bert.
:
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