Toshiba TV29C90 problem; Image fades to black...

[Don Kelly]

----------------------------
<phil-news-nospam@ipal.net> wrote in message
news:g0dt3601543@news4.newsguy.com...

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:

| Yes -you are shorting a part of the winding but the switching is a bit
more
| complex than that so that short circuit currents are limited to
reasonable
| values. It is a multistep operation with reactor switching. On-load tap
| changers are expensive and are generally limited to applications where
this
| is absolutely needed (I have seen one where the tap changer was nearly
as
| large as the transformer).

What about multiple parallel transformers, or at least multiple parallel
windings on the same core (on whichever side the tapping is to be done),
where the taps are stepped incrementally on each winding? Instead of a
shorted winding segment, you'd have windings of differing voltage in
parallel as each of the windings change their taps one at a time.

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| Phil Howard KA9WGN (email for humans: first name in lower case at
ipal.net) |
------------

So you have a differential voltage producing a circulating current through
both windings leading to losses and heating due to circulating currents. In
addition, there would be shifts in the load sharing between the two
secondaries- with the possibility of overloading one of them. Also, you
still haven't solved the problem of switching the current from one tap to
another Note also to shift 2% you would have to make two 2% shifts, one on
each winding so that you are essentially doubling the work and tap changing
equipment while introducing other problems as Daestrom has indicated.
-

--

Don Kelly dhky@shawcross.ca
remove the X to answer

 

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:

| If I read you correctly, you want to use a second secondary (lower power
| rating) which is tapped and put in series with the main secondary. Now once
| you do this, you have in effect a single secondary with taps just as in a
| conventional tapped secondary. Sure the "tapped section" is lower power-
| because it is a lower voltage but it still has to handle the same current.
| Nothing is gained.
| The problem in tap changing is not "power" but the current being switched.

No, that is not what I tried to explain. I'll try again:

The main transformer would have 2 secondaries. These 2 secondaries are NOT
wired in series with each other. The smaller of these secondaries will have
taps. The tapped smaller secondary feeds another smaller transformer. The
larger secondary of the main transformer, and the only secondary of the smaller
auxiliary transformer, would be wired in series. So the taps are only dealing
with the current of the lower power "tapping section". The smaller secondary
of the main transformer, and the primary of the auxiliary transformer, can be
wired for whatever voltage/current works out best.


| In either case the voltage driving short circuit current on tap changing is
| that between taps
| Delta V =A(delta n) Delta Z =B(delta n)^2. where delta n is the change in
| turns between taps. The short circuit current on such a change will be
| proportional to 1/(delta n).
|
| If you want fine control, then you could go to sliding carbon brush as in a
| variac. The first idea of a separate transformer feeding a variac will not
| solve the "too low" voltage problem of the variac because you are still
| dealing with an autotransformer.

In that first scheme, adjusting the variac to the lowest voltage would be
reducing the voltage contributed by the boost transformer. There is still
the original supply voltage going around the variac, "plus" (actually minus)
the buck voltage (to select the range I want). Since the variac is an
autotransformer itself, it merely feeds the primary of the boost transformer.
Note that in this case the "boost" transformer is wired as an isolation
transformer. I should have mentioned that. If needed, I guess I could draw
some ASCII diagrams or try to get something made graphically (all the tools
I have to do that suck, except for Visio which needs Windows to run and I
don't have a spare machine to do that at the moment).

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
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| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

In alt.engineering.electrical daestrom <daestrom@no_spam_heretwcny.rr.com> wrote:
|
| <phil-news-nospam@ipal.net> wrote in message
| news:g0dt3601543@news4.newsguy.com...
|> In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:
|>
|> | Yes -you are shorting a part of the winding but the switching is a bit
|> more
|> | complex than that so that short circuit currents are limited to
|> reasonable
|> | values. It is a multistep operation with reactor switching. On-load tap
|> | changers are expensive and are generally limited to applications where
|> this
|> | is absolutely needed (I have seen one where the tap changer was nearly
|> as
|> | large as the transformer).
|>
|> What about multiple parallel transformers, or at least multiple parallel
|> windings on the same core (on whichever side the tapping is to be done),
|> where the taps are stepped incrementally on each winding? Instead of a
|> shorted winding segment, you'd have windings of differing voltage in
|> parallel as each of the windings change their taps one at a time.
|>
|
| So when one is set for say 118V and the other is set for 120V, you have a
| 118V source connected in parallel with a 120V source and the only impedance
| is the transformer windings??
|
| OUCH!!! I think the magic smoke will be spewing in no time

I was afraid of that.

That also means if you are going to parallel 2 transformers, they better have
exactly the same winding ratio.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
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| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

In alt.engineering.electrical Michael Moroney <moroney@world.std.spaamtrap.com> wrote:

| Phil, did you see daestrom's excellent explanation how they use an
| inductor to prevent a dead short but in a way such that the inductor is
| virtually not there during normal operation (counterflowing currents)?

I believe I missed that.


| If these tap changers are rather expensive, I'm wondering what those
| pole pig "voltage regulators" I mentioned are. I thought they were just
| tapped autotransformers.

Sounds like they may be more of a voltage selector.

One set of transformers I saw once had a voltage selector which also revealed
the voltage to me. Even those these huge things were well guarded behind a
chainlink fence with barbed wire on top, I could clearly read the instructions
on the voltage taps. It listed 5 or 6 different voltages in the 4160 volt
range (I believe that was a middle one). The secondaries were a thick bundle
of insulated wires not on insulator standoffs, so obviously LV, possibly 480V
or 208V. These were 3 single tank transformers in roughly the design style
of a pole pig (round tank) with a control panel on them with the tap control
and some gauge I guessed may be temperature (but I could not see it clear
enough at the distance I was at to be sure). The instructions did indicate
that the transformer must be de-energized (not just unloaded) when making the
change. So I'm guessing they were just to compensate for variations in the
delivered voltage. These transformers were about 1 meter wide and 2.5 meters
high, each (3 of them). I did not see any reference to a kVA rating. They
were also very old looking (pre-WWII). They were humming.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
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| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:

| Just a bitch that we have dealt with before:
|
| Phil- please realize that 207.846096....... is meaningless except that it is
| "about 208". 208V is correct to 3 significant figures which is actually
| better than one can assume to be true in practice. If the voltage line to
| neutral is actually 120.V (note the decimal) then we have 3 significant
| digits implying something between 119.5 Vand 120.5.V
| Then all you can truly claim is 208.V
| If it is 120.0V then there is reason to assume 208.0 V but no more decimals
| than that.
| If you have a meter which gives you 120.000000V with less than 1 part in 120
| million error then you can claim 207.846097V for line to line voltage Do
| you have such a meter?
|
| Engineering and physics students who ignore the principle of "significant
| digits" lose marks for this "decimal inflation".
|
| Sure- you can let the calculator carry the extra digits (as it will do
| internally) but accepting these as gospel truth to the limit of the
| calculator or computer display is simply not on as you can't get better
| accuracy from a calculation than the accuracy of the original data (actually
| you will lose a bit). All that you get rid of is round off errors in
| calculations.
|
| Since, as you say, precise voltage is not really practical, then
| multi-decimal point numbers are meaningless. If we say 120V +/-10% then we
| are talking about 108-132V which for line to line becomes 187-229V (average
| 208V) and any extra decimal points don't mean anything.

You didn't notice the I put on the number?

We've been over this. I know the practice of significant digits, and how
the voltages are designated (two different reasons you can get 208). I do
follow the practice of carrying exactly the result of calculations into
other calculations. I also use over significance in comparison of numbers.

But I also know that rounding is a form of noise. So I avoid it until the
time I end up with the final result. So if I multiply 120 by the square
root of three I do get a number like 207.84609690826527522329356 which is
either carried as-is into the next calculation, or rounded if it is the
final answer. If some other strange calculation happens to give me the
value 207.84609690826527522329356 then I know it is effectively equivalent
to 120 times the square root of three in some way. But if what I get is
208.455732193971783228 then I know it has nothing to do with 120 times the
square root of three, even though it, too, would end up as 208 if rounded
to 3 significant digits.

When it comes to _measured_ amounts, as opposed to synthetic ones, then the
significance rules dictate how to round the results. With synthetic numbers
(e.g. numbers I can just pick), I can also pick the rounding rules for the
final results. But if I don't know that the calculations are done (e.g. I
am not merely giving a designation for a voltage system), where someone else
may take those numbers and do more calculations and round the results, then
I do use more significance. But that is no different to me than just carrying
that number from one calculation stage to another.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

In alt.engineering.electrical Thomas Tornblom <thomas@hax.se> wrote:
| phil-news-nospam@ipal.net writes:
|
|> In alt.engineering.electrical Thomas Tornblom <thomas@hax.se> wrote:
|> | phil-news-nospam@ipal.net writes:
|> |
|> |> In alt.engineering.electrical Thomas Tornblom <thomas@hax.se> wrote:
|> |>
|> |> | Residential power in Norway is normally 230V three phase btw, instead
|> |> | of 400V three phase. Their 230V outlets are two phase and ground
|> |> | instead of one phase, neutral and ground. Their three phase outlets
|> |> | therefore are blue instead of red and have four prongs instead of five.
|> |>
|> |> Is this the system where the voltage is 133 volts relative to ground and 230
|> |> volts between phases (and formerly 127 volts relative to ground and 220 volts
|> |> between phases)?
|> |
|> | Yes.
|> |
|> |>
|> |> If they still use that system, then I'm interested in buying a UPS designed
|> |> for that. But it is my understanding it is phased out in cities and hard to
|> |> find anymore in rural locations.
|> |
|> | It seems they are moving to 400V as well, but I know many Norwegians
|> | are paying a hefty premium on their three phase equipment, like
|> | heatpumps.
|> |
|> | My heatpump use an internally star configured 3x400V compressor, and
|> | it would have been easy to wire it for 3x230V if they had brought out
|> | all the leads.
|>
|> If all 6 leads of the 3 windings are brought out separate, then it can be wired
|> in star for 400/230 volt systems, and in delta for 230/133 volt systems. But
|> for Europe in general there would be little reason to do that. There is also
|> no reason to do that in North America, as we don't have any 360/208 volt systems
|> at all.
|
| It would allow the Norwegians to buy less expensive heatpumps from Sweden
|
| It seems like a very simple and cheap thing to do.

My guess is that in the cities, they have already changed over to a 400/230
system, or at least a 380/220 system that hasn't been voltage adjusted, yet.
What I've heard is the 220/127 system was a leftover in some rural areas of
Norway, and also in Spain. Apparently Suadi Arabia has this system so they
can make use of both European and American single phase appliances. Mexico
also has 220/127 but primarily uses the 127 volt connection (and it's 60 Hz).
The really strange thing is Brazil has 220 volts all around the country,
with 60 Hz in some parts and 50 Hz in others, and used to use the American
120 volt 2-blade outlet/plug with 220 volts (you can be in for a surprise
with that).

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

[JANA]

The boards in these sets are fairly expensive. They are serviced mainly
at the board level only. After replacing any boards the performance of
the set must be checked, and any necessary calibrations performed.

When considering the time and labour, most of the time these TV sets may
not be cost effective to service. I have done estimates on TV sets and
found that the parts alone come to more than the value of the set. The
manufactures charge a lot for the boards and parts, and the transport.
Then there is the labour.

The prices of the newer TV sets are dropping, and at the same time they
are giving more options and better performance at the lower price. I
would not have any idea of how far down the prices can go.

One suggestion that I always follow is to stay with name brand TV sets
only. This way there is authorized support. This way, during the
warranty period it is easy to have service.


--

JANA
_____


"jg2005" <jamiesong2005@yahoo.com.au> wrote in message
news:b8a93bfd-b534-4799-96c8-c1d026dc8a54@s33g2000pri.googlegroups.com...
Hello

First time post to this group. I'm trying to help my Daughter. She has
a Panasonic HD Plasma TV
( 50" purchased in 2005) that has stopped working. It was on,
operating normally and there was a brief noise and the screen went off
& didn't come back on.

Called an authorised Panasonic repairer (we are in Melbourne,
Australia) who is giving a quote. He first said a "board" had blown &
quoted A$650.00 for the repair. Now he has called back & said
replacing that didn't fix it, that another board had also gone & is
now quoting a total of A$1380.00 to fix it & said there still could be
more.

Wondering if anyone would know how many boards these things have and
whether this sounds like a rip-off. A new full HD 50" Panasonic is
around A$2200.00 on special. I'm told the earlier models such as my
Daughter's were built to a higher standard - I know it cost around
$4,500.00 - where they much better?

I know this is a vague question but would appreciate any comments.
Thanks.

 

[Beemer]

"Ablang" <ron916@gmail.com> wrote in message
news:8c97d444-2fbf-496f-8dde-6145e8f4c087@w1g2000prd.googlegroups.com...

The only reason Sharp isn't listed here is because they fail
so radically by computer failure, catching on fire, etc. etc.
that no-one has the piece of crap things fixed due to the cost
of getting "hopefully" one more year out of a dead dog.

They ALWAYS fail shortly after warranty.


-----Original Message-----

Look what they say about it.

http://www.consumerreports.org/cro/appliances/kitchen-appliances/microwave-ovens/reports/repairs-reliability/brand-repair-history/index.htm

The graph shows the percentage of the following brands of over-the-
range (OTR) microwave ovens bought between 2003 through 2007 that have
ever been repaired or had a serious problem. Differences of less than
3 points are not meaningful. KitchenAid has been the most-repair prone
brand. While we lacked enough data for all years to include Sharp in
the chart, we have sufficient data to conclude that it has been a
repair-prone brand. Models within a brand may vary, and changes in
design or manufacture may affect reliability. Still, choosing a brand
with a good repair history can improve your odds of getting a reliable
model.

My Sharp Carousel Convection Microwave is over 30 years old and still used

everyday. Only problem was a cracked front glass which I replaced.

regards,

Beemer

 

[Beemer]

"Ablang" <ron916@gmail.com> wrote in message
news:8c97d444-2fbf-496f-8dde-6145e8f4c087@w1g2000prd.googlegroups.com...

The only reason Sharp isn't listed here is because they fail
so radically by computer failure, catching on fire, etc. etc.
that no-one has the piece of crap things fixed due to the cost
of getting "hopefully" one more year out of a dead dog.

They ALWAYS fail shortly after warranty.


-----Original Message-----

Look what they say about it.

http://www.consumerreports.org/cro/appliances/kitchen-appliances/microwave-ovens/reports/repairs-reliability/brand-repair-history/index.htm

The graph shows the percentage of the following brands of over-the-
range (OTR) microwave ovens bought between 2003 through 2007 that have
ever been repaired or had a serious problem. Differences of less than
3 points are not meaningful. KitchenAid has been the most-repair prone
brand. While we lacked enough data for all years to include Sharp in
the chart, we have sufficient data to conclude that it has been a
repair-prone brand. Models within a brand may vary, and changes in
design or manufacture may affect reliability. Still, choosing a brand
with a good repair history can improve your odds of getting a reliable
model.

My Sharp Carousel Convection Microwave is over 30 years old and still used

everyday. Only problem was a cracked front glass which I replaced.

regards,

Beemer

 

[Tzortzakakis Dimitrios]

? "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> ?????? ??? ??????
news:482b50d2$0$31739$4c368faf@roadrunner.com...

"Tzortzakakis Dimitrios" <noone@nospam.void> wrote in message
news:g0f3n6$bpg$1@mouse.otenet.gr...

? "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> ?????? ??? ??????
news:4829fd51$0$30162$4c368faf@roadrunner.com...

snip
Nice thing about the newer solid-state control systems (AC-Generator/
DC-Traction) is the ability to control wheel-slip. In the old days it
took a skilled engineer (the train-driving kind) to get maximum power
without slipping a lot (and wasting a lot of sand). Now modern units
have speed sensors on each individual wheel set and control the power
flow to individual traction motors. As soon as a wheel set starts to
slip it can redirect power flow to other traction motors to prevent the
slipping set from 'polishing the rail'. This prolongs life of the
wheels and rail and actually improves the maximum tractive effort a
locomotive can deliver. And when hauling 100+ cars of coal in a unit
train up grade, tractive effort is what keeps you moving.

I have no idea about train driving, but in Germany I got a local train
from a small city to Mannheim, and the Lokfuehrer (train driver) was
driving it like a race car... He accelerated fully to 130 km/h, and when
he was close to the next stop, he braked fully, too. It had one E-Lok,
and two cars. Also, the ICE starts like a race car. It's longer than 500
m, 12 cars, and I think it accelerates to 100 km/h in 10 seconds.

There is little doubt that electric trains are faster than other types as
far as acceleration and overall speed.
Yes, because as the germans say-"Sie nehmen Strom direct aus der

Leitung"-They draw power directly from the wire. So it's a higher impulse
current than any on board diesel can provide;_)

snip
Some diesel-electric unitl have six axles and six traction motors. The
trade-off is between how much power you can get to the traction motors
and how much weight you can keep on the wheels to keep them from
slipping. Sand is okay for starting and some special situations, but you
can't carry enough to use it for an entire run. But of course too much
weight and you need more axles to protect the rail from damage
(depending on the size of the rail being used).

But isn't a locomotive by itself heavy enough? Like 120 tons and above,
with fuel and all?
(Check at www.wartsila.com some large diesels). In our new power station,
they have installed two 50 MW, 70,000 HP two-stroke diesels. To see how
2-stroke diesels work, look in www.howstuffworks.com..

I'm quite aware of how a 2-stroke works, as the large EMD's (654 series,
up to V-20 cylinder) that have been around for years are exactly that.
Also how the turbo-charger works, the four different lube-oil pumps
(scavenging, piston-cooling, main, and soak-back). Not to mention the
fuel injectors, overspeed trip, high-crankcase pressure shutdown, and
air-start systems to name a few of the various components. And
Westinghouse air brakes with several variations, and the MU (multi-unit)
interface used to connect several locomotives together and allow them all
to be 'driven' from one cab.
'
Of course you are, but I thought there might be other members of the group,

that don't. I didn't know until I read the article. The large, 15,000 HP, 11
MW diesels we have here at our local power station, have a final steam
stage, for better efficiency. The URL of our local college, where I got my
degree, is www.teiher.gr , but I'm not sure if they got an english version.

But the trouble with overall weight is the combination of weight, power
and rail capacity. When you get to larger units, the rail used on a lot
of roads can't handle more than about 50,000 lbm per wheel set. That
means you're limited to about 100 tons for a unit with just 2 axles per
truck (4 total). Go up to a 120 ton and you need 3 axles per truck. But
a 100 ton, 4-axle unit has 12,500 lbm per axle, while a 120 ton, 6-axle
unit has only 10,000 lbm per axle. If the wheel friction coefficients are
the same, the 4-axle unit can develop 25% more tractive effort when
starting before slipping wheels.

Of course if the 120 ton, 6-axle unit has more overall horsepower, then
even though it develops less tractive effort at low speeds, it can achieve
a higher speed when loaded to it's rated tractive effort. Below a certain
speed, the maximum you can pull is dictated by wheel slip. Then you're
limited by tractive motor cooling up to a second point. Beyond that, the
overall horsepower becomes the limit. Once you're 'horsepower limited',
you can go faster, but only if you can reduce the amount of tractive
effort needed (i.e. you want to go faster, you have to pull fewer cars or
not climb as steep a grade). This 'hp limited speed' is in the range of
just 15 to 20 mph for a lot of 4-axle units, somewhat faster for 6-axle
units.

With typical freight trains in the US, they look at the steepest grade on
the road and figure out enough locomotive units and maximum cars to just
be horsepower limited on that grade. So while the train may go faster on
less steep sections or level grade, it'll be at notch 8 (full throttle)
and struggling to make about 15 mph up the steepest part of the route.
And stalled if one of the locomotive units dies.

So more hp means you may be able to pull it faster, but you can't always
pull as much.

Kind of 'weird' until you work out a few problems, but that's how it
works.

In Germany, they have special locomotives for freight trains, and special

for passenger ones. The former desingned for larger traction power, the
latter for higher speed. I have more experience with ships, since there are
no railroads in Crete, but there's a lot of sea, and islands in Greece
I'll never forget my trip to Rhodes, where my batallion was situated, by
rail from Korinthos (the infamous boot camp) and with ship to Rhodes. She
was full of soldiers and commuters
NB.:There are railroads in continental Greece.


--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.
>

 

[Tzortzakakis Dimitrios]

? "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> ?????? ??? ??????
news:482b50d2$0$31739$4c368faf@roadrunner.com...

"Tzortzakakis Dimitrios" <noone@nospam.void> wrote in message
news:g0f3n6$bpg$1@mouse.otenet.gr...

? "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> ?????? ??? ??????
news:4829fd51$0$30162$4c368faf@roadrunner.com...

snip
Nice thing about the newer solid-state control systems (AC-Generator/
DC-Traction) is the ability to control wheel-slip. In the old days it
took a skilled engineer (the train-driving kind) to get maximum power
without slipping a lot (and wasting a lot of sand). Now modern units
have speed sensors on each individual wheel set and control the power
flow to individual traction motors. As soon as a wheel set starts to
slip it can redirect power flow to other traction motors to prevent the
slipping set from 'polishing the rail'. This prolongs life of the
wheels and rail and actually improves the maximum tractive effort a
locomotive can deliver. And when hauling 100+ cars of coal in a unit
train up grade, tractive effort is what keeps you moving.

I have no idea about train driving, but in Germany I got a local train
from a small city to Mannheim, and the Lokfuehrer (train driver) was
driving it like a race car... He accelerated fully to 130 km/h, and when
he was close to the next stop, he braked fully, too. It had one E-Lok,
and two cars. Also, the ICE starts like a race car. It's longer than 500
m, 12 cars, and I think it accelerates to 100 km/h in 10 seconds.

There is little doubt that electric trains are faster than other types as
far as acceleration and overall speed.
Yes, because as the germans say-"Sie nehmen Strom direct aus der

Leitung"-They draw power directly from the wire. So it's a higher impulse
current than any on board diesel can provide;_)

snip
Some diesel-electric unitl have six axles and six traction motors. The
trade-off is between how much power you can get to the traction motors
and how much weight you can keep on the wheels to keep them from
slipping. Sand is okay for starting and some special situations, but you
can't carry enough to use it for an entire run. But of course too much
weight and you need more axles to protect the rail from damage
(depending on the size of the rail being used).

But isn't a locomotive by itself heavy enough? Like 120 tons and above,
with fuel and all?
(Check at www.wartsila.com some large diesels). In our new power station,
they have installed two 50 MW, 70,000 HP two-stroke diesels. To see how
2-stroke diesels work, look in www.howstuffworks.com..

I'm quite aware of how a 2-stroke works, as the large EMD's (654 series,
up to V-20 cylinder) that have been around for years are exactly that.
Also how the turbo-charger works, the four different lube-oil pumps
(scavenging, piston-cooling, main, and soak-back). Not to mention the
fuel injectors, overspeed trip, high-crankcase pressure shutdown, and
air-start systems to name a few of the various components. And
Westinghouse air brakes with several variations, and the MU (multi-unit)
interface used to connect several locomotives together and allow them all
to be 'driven' from one cab.
'
Of course you are, but I thought there might be other members of the group,

that don't. I didn't know until I read the article. The large, 15,000 HP, 11
MW diesels we have here at our local power station, have a final steam
stage, for better efficiency. The URL of our local college, where I got my
degree, is www.teiher.gr , but I'm not sure if they got an english version.

But the trouble with overall weight is the combination of weight, power
and rail capacity. When you get to larger units, the rail used on a lot
of roads can't handle more than about 50,000 lbm per wheel set. That
means you're limited to about 100 tons for a unit with just 2 axles per
truck (4 total). Go up to a 120 ton and you need 3 axles per truck. But
a 100 ton, 4-axle unit has 12,500 lbm per axle, while a 120 ton, 6-axle
unit has only 10,000 lbm per axle. If the wheel friction coefficients are
the same, the 4-axle unit can develop 25% more tractive effort when
starting before slipping wheels.

Of course if the 120 ton, 6-axle unit has more overall horsepower, then
even though it develops less tractive effort at low speeds, it can achieve
a higher speed when loaded to it's rated tractive effort. Below a certain
speed, the maximum you can pull is dictated by wheel slip. Then you're
limited by tractive motor cooling up to a second point. Beyond that, the
overall horsepower becomes the limit. Once you're 'horsepower limited',
you can go faster, but only if you can reduce the amount of tractive
effort needed (i.e. you want to go faster, you have to pull fewer cars or
not climb as steep a grade). This 'hp limited speed' is in the range of
just 15 to 20 mph for a lot of 4-axle units, somewhat faster for 6-axle
units.

With typical freight trains in the US, they look at the steepest grade on
the road and figure out enough locomotive units and maximum cars to just
be horsepower limited on that grade. So while the train may go faster on
less steep sections or level grade, it'll be at notch 8 (full throttle)
and struggling to make about 15 mph up the steepest part of the route.
And stalled if one of the locomotive units dies.

So more hp means you may be able to pull it faster, but you can't always
pull as much.

Kind of 'weird' until you work out a few problems, but that's how it
works.

In Germany, they have special locomotives for freight trains, and special

for passenger ones. The former desingned for larger traction power, the
latter for higher speed. I have more experience with ships, since there are
no railroads in Crete, but there's a lot of sea, and islands in Greece
I'll never forget my trip to Rhodes, where my batallion was situated, by
rail from Korinthos (the infamous boot camp) and with ship to Rhodes. She
was full of soldiers and commuters
NB.:There are railroads in continental Greece.


--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.
>

 

[Tzortzakakis Dimitrios]

? "Bruce in Bangkok" <decypher_signature@signature.line> ?????? ??? ??????
news:3irn24ho3pgc52s3ju8pe985un7g6o305a@4ax.com...

On 15 May 2008 05:20:27 GMT, phil-news-nospam@ipal.net wrote:

In alt.engineering.electrical Michael Moroney
moroney@world.std.spaamtrap.com> wrote:

| Phil, did you see daestrom's excellent explanation how they use an
| inductor to prevent a dead short but in a way such that the inductor is
| virtually not there during normal operation (counterflowing currents)?

I believe I missed that.


| If these tap changers are rather expensive, I'm wondering what those
| pole pig "voltage regulators" I mentioned are. I thought they were just
| tapped autotransformers.

Sounds like they may be more of a voltage selector.

One set of transformers I saw once had a voltage selector which also
revealed
the voltage to me. Even those these huge things were well guarded behind
a
chainlink fence with barbed wire on top, I could clearly read the
instructions
on the voltage taps. It listed 5 or 6 different voltages in the 4160 volt
range (I believe that was a middle one). The secondaries were a thick
bundle
of insulated wires not on insulator standoffs, so obviously LV, possibly
480V
or 208V. These were 3 single tank transformers in roughly the design
style
of a pole pig (round tank) with a control panel on them with the tap
control
and some gauge I guessed may be temperature (but I could not see it clear
enough at the distance I was at to be sure). The instructions did
indicate
that the transformer must be de-energized (not just unloaded) when making
the
change. So I'm guessing they were just to compensate for variations in
the
delivered voltage. These transformers were about 1 meter wide and 2.5
meters
high, each (3 of them). I did not see any reference to a kVA rating.
They
were also very old looking (pre-WWII). They were humming.


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 other "cans" you often see on poles are capacitors used to adjust
the power factor on some secondaries.

Or disconnect switches, plain or with high-voltage fuses.
Bruce-in-Bangkok

--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.

 

[Tzortzakakis Dimitrios]

? "Bruce in Bangkok" <decypher_signature@signature.line> ?????? ??? ??????
news:3irn24ho3pgc52s3ju8pe985un7g6o305a@4ax.com...

On 15 May 2008 05:20:27 GMT, phil-news-nospam@ipal.net wrote:

In alt.engineering.electrical Michael Moroney
moroney@world.std.spaamtrap.com> wrote:

| Phil, did you see daestrom's excellent explanation how they use an
| inductor to prevent a dead short but in a way such that the inductor is
| virtually not there during normal operation (counterflowing currents)?

I believe I missed that.


| If these tap changers are rather expensive, I'm wondering what those
| pole pig "voltage regulators" I mentioned are. I thought they were just
| tapped autotransformers.

Sounds like they may be more of a voltage selector.

One set of transformers I saw once had a voltage selector which also
revealed
the voltage to me. Even those these huge things were well guarded behind
a
chainlink fence with barbed wire on top, I could clearly read the
instructions
on the voltage taps. It listed 5 or 6 different voltages in the 4160 volt
range (I believe that was a middle one). The secondaries were a thick
bundle
of insulated wires not on insulator standoffs, so obviously LV, possibly
480V
or 208V. These were 3 single tank transformers in roughly the design
style
of a pole pig (round tank) with a control panel on them with the tap
control
and some gauge I guessed may be temperature (but I could not see it clear
enough at the distance I was at to be sure). The instructions did
indicate
that the transformer must be de-energized (not just unloaded) when making
the
change. So I'm guessing they were just to compensate for variations in
the
delivered voltage. These transformers were about 1 meter wide and 2.5
meters
high, each (3 of them). I did not see any reference to a kVA rating.
They
were also very old looking (pre-WWII). They were humming.


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 other "cans" you often see on poles are capacitors used to adjust
the power factor on some secondaries.

Or disconnect switches, plain or with high-voltage fuses.
Bruce-in-Bangkok

--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.

 

[Tzortzakakis Dimitrios]

Ď <phil-news-nospam@ipal.net> Ýăńářĺ óôď ěŢíőěá
news:g0f71q111lk@news3.newsguy.com...

In alt.engineering.electrical Tzortzakakis Dimitrios <noone@nospam.void
wrote:

| Professional washing machines. One of my very first days 'in the field'
was
| to connect some of them. They have a large heating element, you can
connect
| it single phase, or 3 phase, it just heats up faster (of course) when
you
| connect it 3 phase. (they have a single phase motor, so it works also in
| pure 230 V).

If it has 3 elements rated for 230 volts, with 3 separate connections that
would be to three separate phase for a three phase feed, and all connected
to the one phase for a single phase feed, then it should heat up at the
same
speed, while drawing three times the current (not accounting for the
motor).

I don't know why it should heat up faster in three phase, or why you would
say "of course" about it. I would think it would heat up faster if you
took
it over to London and hooked it up to a 240 volt supply.

Maybe you connected with single phase just one element? The rest two

remained unconnected? (3 230 volts elements, connected wye). I'm sure it
heated up faster, in 3 phase connection.





--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.

 

[Tzortzakakis Dimitrios]

Ď <phil-news-nospam@ipal.net> Ýăńářĺ óôď ěŢíőěá
news:g0f71q111lk@news3.newsguy.com...

In alt.engineering.electrical Tzortzakakis Dimitrios <noone@nospam.void
wrote:

| Professional washing machines. One of my very first days 'in the field'
was
| to connect some of them. They have a large heating element, you can
connect
| it single phase, or 3 phase, it just heats up faster (of course) when
you
| connect it 3 phase. (they have a single phase motor, so it works also in
| pure 230 V).

If it has 3 elements rated for 230 volts, with 3 separate connections that
would be to three separate phase for a three phase feed, and all connected
to the one phase for a single phase feed, then it should heat up at the
same
speed, while drawing three times the current (not accounting for the
motor).

I don't know why it should heat up faster in three phase, or why you would
say "of course" about it. I would think it would heat up faster if you
took
it over to London and hooked it up to a 240 volt supply.

Maybe you connected with single phase just one element? The rest two

remained unconnected? (3 230 volts elements, connected wye). I'm sure it
heated up faster, in 3 phase connection.





--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.

 

[Michael Moroney]

phil-news-nospam@ipal.net writes:

In alt.engineering.electrical Michael Moroney <moroney@world.std.spaamtrap.com> wrote:

| If these tap changers are rather expensive, I'm wondering what those
| pole pig "voltage regulators" I mentioned are. I thought they were just
| tapped autotransformers.

Sounds like they may be more of a voltage selector.

Probably.

One set of transformers I saw once had a voltage selector which also revealed
the voltage to me. Even those these huge things were well guarded behind a
chainlink fence with barbed wire on top, I could clearly read the instructions
on the voltage taps. It listed 5 or 6 different voltages in the 4160 volt
range (I believe that was a middle one). The secondaries were a thick bundle
of insulated wires not on insulator standoffs, so obviously LV, possibly 480V
or 208V. These were 3 single tank transformers in roughly the design style
of a pole pig (round tank) with a control panel on them with the tap control
and some gauge I guessed may be temperature (but I could not see it clear
enough at the distance I was at to be sure). The instructions did indicate
that the transformer must be de-energized (not just unloaded) when making the
change. So I'm guessing they were just to compensate for variations in the
delivered voltage. These transformers were about 1 meter wide and 2.5 meters
high, each (3 of them). I did not see any reference to a kVA rating. They
were also very old looking (pre-WWII). They were humming.

Interesting. Around here I see control boxes on the pole-mounted ones.
Maybe they have something to read. (I know some read SIEMENS in large
letters on some of them, apparently the manufacturer)

Long ago, during one of the past "oil crises" (1973 or 1978 or so) they
proposed cutting back the voltage delievered to one's home by 5-10% from
the normal voltage, a "brownout", "to save energy". I once wondered how
they may have done that, assuming any automated regulating equipment was
hardwired to provide 13.8kV or whatever, and that setting couldn't easily
be changed. Also, any automated regulators downstream would try to
compensate for the lower supply and raise their output voltage, so all
regulators would have to be adjusted. But if was done manually, for
equipment not tied to a particular voltage, they could do it on a
substation-by-substation basis, and ones "downstream" could have been
left alone.

 

[Michael Moroney]

phil-news-nospam@ipal.net writes:

In alt.engineering.electrical Michael Moroney <moroney@world.std.spaamtrap.com> wrote:

| If these tap changers are rather expensive, I'm wondering what those
| pole pig "voltage regulators" I mentioned are. I thought they were just
| tapped autotransformers.

Sounds like they may be more of a voltage selector.

Probably.

One set of transformers I saw once had a voltage selector which also revealed
the voltage to me. Even those these huge things were well guarded behind a
chainlink fence with barbed wire on top, I could clearly read the instructions
on the voltage taps. It listed 5 or 6 different voltages in the 4160 volt
range (I believe that was a middle one). The secondaries were a thick bundle
of insulated wires not on insulator standoffs, so obviously LV, possibly 480V
or 208V. These were 3 single tank transformers in roughly the design style
of a pole pig (round tank) with a control panel on them with the tap control
and some gauge I guessed may be temperature (but I could not see it clear
enough at the distance I was at to be sure). The instructions did indicate
that the transformer must be de-energized (not just unloaded) when making the
change. So I'm guessing they were just to compensate for variations in the
delivered voltage. These transformers were about 1 meter wide and 2.5 meters
high, each (3 of them). I did not see any reference to a kVA rating. They
were also very old looking (pre-WWII). They were humming.

Interesting. Around here I see control boxes on the pole-mounted ones.
Maybe they have something to read. (I know some read SIEMENS in large
letters on some of them, apparently the manufacturer)

Long ago, during one of the past "oil crises" (1973 or 1978 or so) they
proposed cutting back the voltage delievered to one's home by 5-10% from
the normal voltage, a "brownout", "to save energy". I once wondered how
they may have done that, assuming any automated regulating equipment was
hardwired to provide 13.8kV or whatever, and that setting couldn't easily
be changed. Also, any automated regulators downstream would try to
compensate for the lower supply and raise their output voltage, so all
regulators would have to be adjusted. But if was done manually, for
equipment not tied to a particular voltage, they could do it on a
substation-by-substation basis, and ones "downstream" could have been
left alone.

 

[Tzortzakakis Dimitrios]

Ď <phil-news-nospam@ipal.net> Ýăńářĺ óôď ěŢíőěá
news:g0gi9j51s3j@news5.newsguy.com...

In alt.engineering.electrical Thomas Tornblom <thomas@hax.se> wrote:
| phil-news-nospam@ipal.net writes:
|
|> In alt.engineering.electrical Thomas Tornblom <thomas@hax.se> wrote:
|> | phil-news-nospam@ipal.net writes:
|> |
|> |> In alt.engineering.electrical Thomas Tornblom <thomas@hax.se> wrote:
|> |
|> |> | Residential power in Norway is normally 230V three phase btw,
instead
|> |> | of 400V three phase. Their 230V outlets are two phase and ground
|> |> | instead of one phase, neutral and ground. Their three phase
outlets
|> |> | therefore are blue instead of red and have four prongs instead of
five.
|> |
|> |> Is this the system where the voltage is 133 volts relative to ground
and 230
|> |> volts between phases (and formerly 127 volts relative to ground and
220 volts
|> |> between phases)?
|> |
|> | Yes.
|> |
|> |
|> |> If they still use that system, then I'm interested in buying a UPS
designed
|> |> for that. But it is my understanding it is phased out in cities and
hard to
|> |> find anymore in rural locations.
|> |
|> | It seems they are moving to 400V as well, but I know many Norwegians
|> | are paying a hefty premium on their three phase equipment, like
|> | heatpumps.
|> |
|> | My heatpump use an internally star configured 3x400V compressor, and
|> | it would have been easy to wire it for 3x230V if they had brought out
|> | all the leads.
|
|> If all 6 leads of the 3 windings are brought out separate, then it can
be wired
|> in star for 400/230 volt systems, and in delta for 230/133 volt
systems. But
|> for Europe in general there would be little reason to do that. There
is also
|> no reason to do that in North America, as we don't have any 360/208
volt systems
|> at all.
|
| It would allow the Norwegians to buy less expensive heatpumps from
Sweden
|
| It seems like a very simple and cheap thing to do.

My guess is that in the cities, they have already changed over to a
400/230
system, or at least a 380/220 system that hasn't been voltage adjusted,
yet.
What I've heard is the 220/127 system was a leftover in some rural areas
of
Norway, and also in Spain. Apparently Suadi Arabia has this system so
they
can make use of both European and American single phase appliances.
Mexico
also has 220/127 but primarily uses the 127 volt connection (and it's 60
Hz).
The really strange thing is Brazil has 220 volts all around the country,
with 60 Hz in some parts and 50 Hz in others, and used to use the American
120 volt 2-blade outlet/plug with 220 volts (you can be in for a surprise
with that).

--
There should be no problem with the frequency, the local US base (In

Gournes-decomissioned after the end of the Cold War) used a regular 15 kV,
50 Hz feed, from the cretan grid, which was stepped down to 4150 volts and
then to 120/240. All with US switchgear and tranformers! (NB for US guys.#10
wire gauge->10 mm2 main feed of residence, #12 ->6 mm2 stove,#14->4 mm2
water heaters, #16->2.5 mm2 washing machines, dryers, #18->1.5 mm2
lighting.-approximately). I think that the personnel of the base used
standard US fluorescent light fixtures and other equipment, sone of it was
left as some of the buildings "inherited" by the greek state, were converted
by us to 230/400 volts, with regular Schuko receptacles.


--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.

 

[Tzortzakakis Dimitrios]

Ď <phil-news-nospam@ipal.net> Ýăńářĺ óôď ěŢíőěá
news:g0gi9j51s3j@news5.newsguy.com...

In alt.engineering.electrical Thomas Tornblom <thomas@hax.se> wrote:
| phil-news-nospam@ipal.net writes:
|
|> In alt.engineering.electrical Thomas Tornblom <thomas@hax.se> wrote:
|> | phil-news-nospam@ipal.net writes:
|> |
|> |> In alt.engineering.electrical Thomas Tornblom <thomas@hax.se> wrote:
|> |
|> |> | Residential power in Norway is normally 230V three phase btw,
instead
|> |> | of 400V three phase. Their 230V outlets are two phase and ground
|> |> | instead of one phase, neutral and ground. Their three phase
outlets
|> |> | therefore are blue instead of red and have four prongs instead of
five.
|> |
|> |> Is this the system where the voltage is 133 volts relative to ground
and 230
|> |> volts between phases (and formerly 127 volts relative to ground and
220 volts
|> |> between phases)?
|> |
|> | Yes.
|> |
|> |
|> |> If they still use that system, then I'm interested in buying a UPS
designed
|> |> for that. But it is my understanding it is phased out in cities and
hard to
|> |> find anymore in rural locations.
|> |
|> | It seems they are moving to 400V as well, but I know many Norwegians
|> | are paying a hefty premium on their three phase equipment, like
|> | heatpumps.
|> |
|> | My heatpump use an internally star configured 3x400V compressor, and
|> | it would have been easy to wire it for 3x230V if they had brought out
|> | all the leads.
|
|> If all 6 leads of the 3 windings are brought out separate, then it can
be wired
|> in star for 400/230 volt systems, and in delta for 230/133 volt
systems. But
|> for Europe in general there would be little reason to do that. There
is also
|> no reason to do that in North America, as we don't have any 360/208
volt systems
|> at all.
|
| It would allow the Norwegians to buy less expensive heatpumps from
Sweden
|
| It seems like a very simple and cheap thing to do.

My guess is that in the cities, they have already changed over to a
400/230
system, or at least a 380/220 system that hasn't been voltage adjusted,
yet.
What I've heard is the 220/127 system was a leftover in some rural areas
of
Norway, and also in Spain. Apparently Suadi Arabia has this system so
they
can make use of both European and American single phase appliances.
Mexico
also has 220/127 but primarily uses the 127 volt connection (and it's 60
Hz).
The really strange thing is Brazil has 220 volts all around the country,
with 60 Hz in some parts and 50 Hz in others, and used to use the American
120 volt 2-blade outlet/plug with 220 volts (you can be in for a surprise
with that).

--
There should be no problem with the frequency, the local US base (In

Gournes-decomissioned after the end of the Cold War) used a regular 15 kV,
50 Hz feed, from the cretan grid, which was stepped down to 4150 volts and
then to 120/240. All with US switchgear and tranformers! (NB for US guys.#10
wire gauge->10 mm2 main feed of residence, #12 ->6 mm2 stove,#14->4 mm2
water heaters, #16->2.5 mm2 washing machines, dryers, #18->1.5 mm2
lighting.-approximately). I think that the personnel of the base used
standard US fluorescent light fixtures and other equipment, sone of it was
left as some of the buildings "inherited" by the greek state, were converted
by us to 230/400 volts, with regular Schuko receptacles.


--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.

 

[Michael Moroney]

Bruce in Bangkok <decypher_signature@signature.line> 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.

What I was talking about appear to be used to adjust for supplied voltage
(they're often used right after a stepdown transformer bank) or long
runs, which may produce somewhat variable voltages that need adjustment
at times.

The other "cans" you often see on poles are capacitors used to adjust
the power factor on some secondaries.

Around here, capacitors for power factor compensation are rectangular
boxes with two bushings on top, on poles, in banks of 3, 6 or sometimes 9.

Like the ones Phil mentioned, the cans I talked about hum.