Speaking of electricity.............

[toggleswitch]

Network losses in Latin America & Brazil may be not only infrastructure losses, but the poor frequently "tap-in" to the grid to suck free electricity out. Due to the number and percentage of poor, officals may be forced to turn a blind-eye for the sake of social stability.

 

[nasadowsk]

There are such things as big loads on single phase, though. All of Amtrak's NEC south of NYC is single phase 25hz, and NJT's 60hz segments are single phase. The Red Bank Substation (Coast-2) pulls in from one phase of the 230,000 volt line, and goes to two single phase 10MVA transformers. BTW, the available fault current on the 230kv side exceeds 15,000 amps (!). And there's a big friendly high speed grounding switch on the system. And yeah, they've fired it a few times...

4160 is common for larger water pumps in treatment plants - 2000HP motors, and yes, VFDs provided. Neat stuff

 

[wannapinkset]

Suds, thats who told me that. Dont need to wake him.

Yep, five years of college he had and not at the ABC academy, m'k? I said UNION, card carrying JIW.

 

[sudsmaster]

"The thing is, the higher the volts the lower the watts, the lower the bill."

That is just plain flat-out WRONG, and nayone who makes such a statement doesn't know basic electronics.

Simple as that, and I don't need a union card to know that.

 

[tolivac]

the place where I work all of the high power shortwave transmitters run off 4160V 3 ph.Quite a jump from commercial broadcast ones that run off 208 or 480V 3 ph.I am afraid the "higherthe volts-lower the watts-the lower the bill" just doesn't apply to the site I am working at right now.electric bills here are unbeleivable!We measure power in "Megawatt" hrs here.also the 4160V building feeders are stepped down to 208-120,230V3ph and 480-277V 3Ph.4160V is a coomon power feed for larger Govt buildings.

 

[panthera]

I am shocked, shocked I tell you

Ok, the snarkiness level on this thread is rising. So why am I surprised.
Cripes, dahlinks!
The question is interesting, if you want to get all het up, just go read the last thread on this topic - there's enough venom there to poison an army.
Yeah, watts are not the same as amps or volts alone.
You can think of watts as 'work'. They are the product you get when you multiply amps and voltage. It works like this:
120V x 5amps = 600Watts.
240V x 2.5 amps = 600 watts.
As somebody said, the size of the wire is determined by the current load (which we call 'amps') not the voltage. Since you can lower the current by increasing the voltage, high voltage wires are relatively thinner than low voltage wires.
I keep waiting for somebody to explain Ohm's law...then have someone else jump in and point out that 'law' is not politically correct anymore and, anyway, it only applies to resistance loads not inductive or capcitive...
Oh, and, please, my volts * amps = watts only applies to direct current. I can do the formulas for AC and other non-sinosoidal but they fall into the same category as the dihydrogenoxide...
So back to the applications of all this stuff. I notice that some 24" combo washer/dryers in the US are 240V. Does anyone know if the washer motor is also running 240V or just 120?

 

[sudsmaster]

Panthera,

Actually volts*amps=watts applies to AC circuits as well, as long as they are purely resistive loads (like incandescent lighting). Once inductance and capacitance is introduced, however, the alternating current introduces fun stuff like power factor. This is why some AC types of equipment is rated as "volt-amps", probably because that is a more realistic indication of the wire gauge needed in the line circuit to supply the device. In such cases the amp load on the line wiring is virtually always greater than the wattage consumed would otherwise indicate.

For this reason, also, most power companies charge a surcharge on the watts measured by the meter, to account for power factors of less than unity. For most residential accounts, the power factor is assumed to be a certain value, and rates adjusted accordingly. For some if not most commercial/industrial accounts, the utility will measure the actual cumulative power factor of the facility and surcharge accordingly. This gives commercial customers the incentive to fine-tune their equipment to bring the power factor as close to unity as possible.

 

[panthera]

right you are

Rich, and I thought I had said that. Truly, Ohm's law is more an approximation in resistive AC circuits, but close enough for government work in any case.
I worked through what I wrote several times to make sure I did not write anything which could be interpreted wrongly, so forgive me for being cautious.
For the sake of completeness, take a look at the link below for the formulas to calculate actual and apparent power in AC circuits (scroll down).
I have tried so very hard to stay away from the induction/capacitance, serial vs. parallel aspects and, especially Kirchhof's little ditty where everything adds up to zero...
I still think we should waste less time arguing the fine details (surprised nobody has gotten all het up about which "direction" electrons flow) and focus more on the practical aspects of single-phase, split-phase (if that phrase is good enough for the NEC, it is good enough for me) and poly-phase power.

http://www.ibiblio.org/kuphaldt/electricCircuits/Ref/REF_1.html#xtocid1249819

 

[sudsmaster]

Absolutely, Panthera.

The practical impact of single vs. split vs. poly is that few if any of us are lucky enough to have polyphase power in our homes, at least in the USA. I say lucky because I'm looking to buy some machining equipment for my shop at home, and all the older, robust stuff worth looking at runs on three-phase power. A rotary phase converter will be needed to power it, but I dislike having to waste energy doing that conversion, plus the added complexity a phase converter can introduce.

Tree phase is wonderful for running motors, since it provides everything the motor needs to both start and run. Single and split phase both require added windings, capacitors, and a entrifugal switch to start the motor turning, as Tolivac already explained quite well.

 

[panthera]

Rich

My understand of the newer three phase generators is that they are considerably more efficient than the older systems which, having no logic, were relatively wasteful.
I had to relearn trig. when I was studying the basics of electrical engineering - I can't teach the vocabulary for the Natural Sciences and Engineering unless I actually have passed the exams in the various courses. Every so often I manage just a glimpse of the beauty of these systems...

 

[MrX]

European power's mostly distributed as 3-phase

Interestingly, in europe power's generally distributed in one of two ways:

4 Wires run around the neighbourhood from a large transformer. 3 phases and 1 neutral.

Each residential unit takes 1 of the phases + the neutral. They spread the load over the 3 phases, with each house taking a different phase.

The odd large home, or home with a workshop etc will take full 3-phase power.
This is the usual way power's distributed in Ireland and the UK etc.

or b) Most houses take full 3 phase power spreading the load across all the phases.
This tends to be more common in Germany etc