Discussion:
What 60 HZ Feels Like - Even Some On-Topic Stuff
(too old to reply)
Peter Wieck
2019-03-29 18:32:21 UTC
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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
Big Bad Bob
2019-03-29 23:46:34 UTC
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Post by Peter Wieck
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.
mechanical load/speed regulators are very reliable, mechanically simple,
and do a really good job. why "improve" something that works so well?

They typically adjust the frequency setpoint on all of the generators,
which would be overseen by the ISO, and then allow the load/freq slope
to balance load between them all. i would expect that certain kinds of
generators would have a more aggressive slope than others. Nuke plants
need to keep a constant power output, but others (like hydroelectric)
can bounce all over the place as needed to manage grid power levels.

I expect that wind/solar will also try to run at 100% all of the time as
well, to keep costs down.
Trevor Wilson
2021-03-17 05:13:44 UTC
Permalink
Post by Peter Wieck
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.
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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Trevor Wilson
2021-03-17 06:11:42 UTC
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Post by Trevor Wilson
a dozen or so racks full of vacuum tubes. The system was known as TASI
(Time Alignment Speech Interpolation).
**That would be Time ASSIGNMENT.
--
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Terry Schwartz
2021-03-24 03:01:29 UTC
Permalink
Post by Trevor Wilson
Post by Trevor Wilson
a dozen or so racks full of vacuum tubes. The system was known as TASI
(Time Alignment Speech Interpolation).
**That would be Time ASSIGNMENT.
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
And your cell phone probably has 10000x the power.
Trevor Wilson
2021-03-24 05:11:42 UTC
Permalink
Post by Terry Schwartz
Post by Trevor Wilson
Post by Trevor Wilson
a dozen or so racks full of vacuum tubes. The system was known as TASI
(Time Alignment Speech Interpolation).
**That would be Time ASSIGNMENT.
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
And your cell phone probably has 10000x the power.
**And then some. Still, the old TASI was mighty impressive back then.
Big Bad Bob
2021-04-02 16:16:05 UTC
Permalink
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.
Well it's kinda like this...

When I was in the Navy I was qualified to run the nuclear reactor on a
sub. This included being qualified to run the electric plant as well
(turbine generators, motor/generator sets, and a diesel generator mostly
for emergencies). The phase meter you refer to is used to parallel two
3-phase generators. The Navy used a manual control system that was
relatively foolproof, somewhat universally throughout the fleet.
Submarines were pretty much the same that way.

If you plot the sine wave patterns for the generator output vs power
already on the bus (let's say with an o-scope), in order to minimize the
inevitable current spike you get when shutting the generator's breaker,
the output and the line have to be in phase and at the same AC voltage.
Ideally it's a zero volt difference, but in practice the best way to do
it is as follows:

a) speed regulator on the engine has a "load curve" so that increasing
its setting may keep the same frequency, but takes up more load from the
other generators and utility power.

b) The incoming generator is moving slightly faster. As the phase
needle spins clockwise, you time shutting the breaker [which has a delay
- you get used to how long that is] so that it physically shuts the
moment the needle is at the top [in phase].

c) once the breaker shuts you immediately put load on the generator by
increasing its speed regulator setting. You don't want a turbine
"windmilling" nor an engine being driven by incoming power for any
length of time. [some generators might have reverse-power trips on
their breakers to prevent this]

d) when you 'secure' the generator, you decrease the speed regulator
setting until all the load is off, then pop open the breaker just as it
hits zero.

Hopefully that explains how those phase meters work and why they are there.

Now, for the question "what could happen if you do it wrong"... well, in
the worst case scenario (180 degrees out of phase)

a) melt the contacts on the breaker, hopefuly not causing a phase-phase
short in the process
b) start a major electrical fire (buswork or generator itself)
c) physically torque the generator and damage the shaft and/or windings
d) snap the crankshaft on the diesel generator
e) torque the engine/generator so hard they either separate from one
another, or jump off of their mounts and damage things while rolling
around the room


Yes. You do NOT want to parallel them out of phase. EVAR. It is worse
than suddenly putting a shorting bar across all 3 phases simultaneously.
--
(aka 'Bombastic Bob' in case you wondered)

'Feeling with my fingers, and thinking with my brain' - me

'your story is so touching, but it sounds just like a lie'
"Straighten up and fly right"
Lord Valve
2021-04-03 11:30:33 UTC
Permalink
Post by Big Bad Bob
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.
Well it's kinda like this...
When I was in the Navy I was qualified to run the nuclear reactor on a
sub. This included being qualified to run the electric plant as well
(turbine generators, motor/generator sets, and a diesel generator mostly
for emergencies). The phase meter you refer to is used to parallel two
3-phase generators. The Navy used a manual control system that was
relatively foolproof, somewhat universally throughout the fleet.
Submarines were pretty much the same that way.
If you plot the sine wave patterns for the generator output vs power
already on the bus (let's say with an o-scope), in order to minimize the
inevitable current spike you get when shutting the generator's breaker,
the output and the line have to be in phase and at the same AC voltage.
Ideally it's a zero volt difference, but in practice the best way to do
a) speed regulator on the engine has a "load curve" so that increasing
its setting may keep the same frequency, but takes up more load from the
other generators and utility power.
b) The incoming generator is moving slightly faster. As the phase
needle spins clockwise, you time shutting the breaker [which has a delay
- you get used to how long that is] so that it physically shuts the
moment the needle is at the top [in phase].
c) once the breaker shuts you immediately put load on the generator by
increasing its speed regulator setting. You don't want a turbine
"windmilling" nor an engine being driven by incoming power for any
length of time. [some generators might have reverse-power trips on
their breakers to prevent this]
d) when you 'secure' the generator, you decrease the speed regulator
setting until all the load is off, then pop open the breaker just as it
hits zero.
Hopefully that explains how those phase meters work and why they are there.
Now, for the question "what could happen if you do it wrong"... well, in
the worst case scenario (180 degrees out of phase)
a) melt the contacts on the breaker, hopefuly not causing a phase-phase
short in the process
b) start a major electrical fire (buswork or generator itself)
c) physically torque the generator and damage the shaft and/or windings
d) snap the crankshaft on the diesel generator
e) torque the engine/generator so hard they either separate from one
another, or jump off of their mounts and damage things while rolling
around the room
Yes. You do NOT want to parallel them out of phase. EVAR. It is worse
than suddenly putting a shorting bar across all 3 phases simultaneously.
--
(aka 'Bombastic Bob' in case you wondered)
'Feeling with my fingers, and thinking with my brain' - me
'your story is so touching, but it sounds just like a lie'
"Straighten up and fly right"
SO - you was a squid, huh? Me too - avionics technician. My class
was the last one that was taught entirely on tubes - after us, the
training manuals and films and whatnot were all updated and the
boots all had to learn about them three-legged fuses along with
the tubes. That was in 1968. Those old training rigs were really
a hoot - every single component in the unit was mounted on a
small turret board with a thumb-wheel hold-down fastener on
each end. The instructors had a big box of BAD components
which were outfitted the same way; before class, they'd go through
and randomly install bad parts in the trainer chasses - that way,
when you powered 'em up, they all had different stuff wrong with
'em, to which you applied your recently-acquired troubleshooting
skills in order to find the fault. Sometimes, you found it. ;-) I wonder
what happened to all those old training rigs...

Lord Valve / Fat Willie

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