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Trevor Wilson[_3_] Trevor Wilson[_3_] is offline
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Default What 60 HZ Feels Like - Even Some On-Topic Stuff

On 30/03/2019 5:32 am, Peter Wieck wrote:
As an aside, I toured the Veolia Steam Plant in Philadelphia, yesterday. This plant has been in continuous operation since it opened in 1909, and is quite a remarkable place. I got to be up-close-and-personal with the equipment, including the steam and gas turbines, the boilers, pumps, controls, switchgear, powerhouse and uplink.

Standing under the main step-up transformer (2,300 VAC to 23,000 VAC) is a truly visceral experience. Once one feels that level of "HUM", one will never mistake 60 for 120 ever again.

Relevance:

60 HZ hum suggests a bad or failing rectifier.
120 HZ hum suggests bad or failing filter caps.
50 & 100 for our Euro and Asian friends.

Amazing amount of mechanical-feedback devices in use in these plants - it seems that VFDs and great many "modern" grid-tie devices are simply not sufficiently rugged or reliable at this scale.

Peter Wieck
Melrose Park, PA


**Interesting. Back in 1971-ish, when I was in training, I was posted to
a SW radio transmission facility. A big sucker. Anyway, since it was a
partly gummint operation, they had multiple backups for mains power.
There were two, large Diesel generator units (maybe 2.5Metres high, as I
recall). Cooling water was routed through the fountain in the front of
the facility for some reason. If the fountain was operating, then you
knew that the Diesels were running. Each week, the Diesels would be
fired up for 30 minutes or so for testing. There was a big meter mounted
between the Diesels. Apparently, the needle had to be centred, when the
Diesels had reached an in-phase operation. Then they could be switched
in. I asked what would happen if they were switched when not in phase.
Apparently all the trainees asked that question. No one knew for sure
and they didn't want to find out. Probably a lot of structurual damage
would occur. At another facility, there was a huge battery room,
consisting of many (100+) Pyrex„¢ lead acid batteries, enabling the
facility to operate for several days without power. We were given a
warning that, if the 2 Tonne fire door closed and we were trapped
inside, that we should climb on top of the Diesel generator, so we could
hopefully escape suffocation, when the room filled with CO2. Fun days.

And, to bring this back on-topic the organisation was the main
communication hub from Australia to the rest of the world (Satellite,
submarine cable, SW radio, etc). As such they employed a 2.5kV power
supply to power the vacuum tube repeaters between here an New Zealand.
Even better, there was a system on the first floor that comprised about
a dozen or so racks full of vacuum tubes. The system was known as TASI
(Time Alignment Speech Interpolation). It was a mind-bendingly
complicated system, that detected silent spots in voice comms and
inserted another section of voice comms into the silent bits. It
effectively doubled the bandwidth of the cable. ALL with valves. Even
the CROs used to service the gear were tube Tektronix units (yet the
rest of the facility used all SS CROs). Fascinating stuff. The computer
on the top floor (it occupied the whole floor) had a 2 Metre long drum
drive. Hundreds of heads, very fast access time. Lots of cool stuff. My
cell phone probably has ten times the power.

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