In alt.engineering.electrical David Lesher wrote:
| Bruce in Bangkok writes:
|
|
|All distribution transformers, sometimes called "pole pigs", that I
|have seen had some sort of voltage adjusting system, usually referred
|to as taps. Usually they are an actual bolted "tap" and you open the
|transformer and set the output voltage by making the proper tap
|connection when the transformer is installed and frankly it is usually
|ignored thereafter.
|
| The pole pigs here [7200v in/120-240 out] are fixed tap, I'm told. Saves
| money. I think they are fused at 10A in. Older ones may have settable taps.
|
|The other "cans" you often see on poles are capacitors used to adjust
|the power factor on some secondaries.
|
| Capacitors are in various places but we also have three 7200V line
| regulators a block away, one on each primary phase. They are
| auto-transformers, with allegedly auto-controlled tap changers, much as
| the other poster described. [But his description is more complex than
| I recall from the class covering same. The essential aspect was you
| CAN short two taps together while switching; the inductance limits the
| current change while you do..]
|
| I say "allegedly" as twice now, the regulators have stuck and my UPS
| woke me up at 2:30AM with notices it was disconnecting from the now-128v+
| line. I solved the issue that night by putting a Variac in the line
| ahead of it, and cranking it down.
|
| It took multiple calls and finally PSC [oversight agency] complaints
| to get PEPCO to fix the damn thing.
|
| I envy EU houses. If we had regular 240V/30A+ outlets, I'd be able to
| buy a snowblower with real guts. The 120v@15A ones are wimpy.

So put one in.

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