280V motor on 230V circuit

Is the unit for "Are you getting any lately?", still furlongs per fortnight?

I certainly remember the poundal.

The various old english measures: chain, rod, quarter, peck, etc, were, of course, very useful to teach children arithmetic since they all came with different bases.

and of course you can measure viscosity in Acres per year - if you want to.

In message , charles writes

You forgot the poles and perches, the bushels, and of course, the LSD.

In alt.engineering.electrical Anthony Matonak wrote: | charles wrote: |> krw wrote: |>> bz+ snipped-for-privacy@ch100-5.chem.lsu.edu says... |>>> It is necessary to distinguish between mass and force but they are both |>>> measured in pounds in the english system. |> |>> The "English" system uses the "stone" as the measurement of mass. |>> The pound ('lb') is the unit of *FORCE*. |> |> The 'Stone' is a unit of mass, not "The unit of mass" |> |> All the engineering I ever learned in the British (Imperial) system used |> pounds. | | I always thought the British pound was a unit of currency. :)

That's why I never wanted to carry around the British currency. It can be quite a chore to carry 50 pounds in your pocket :-)

Well, if it's true that "A pint's a pound the world around" then you don't need to carry it all in your pocket. :-D

that saying must be some years old.

A pint's now about three pounds ;-(

Also a US pint (16 fl.oz) is smaller than an Imperial pint (20 fl.oz), so that would make beer more expensive in the US ;-)

Just wait until you run into BTU's....

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.

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.

Don't generalize too much. Multi-tap transformers are the normal for rural co-ops. I have a couple sitting in my shop right now. It's cheaper to change taps on the transformer than it is to deal with the various voltages that happen around a large geographic area.

You can have as many of those outlets as you want. In fact, I did just that in my restaurant. Every place there was an outlet I installed a double ganged box and included one 20 amp 120 volt outlet and one 30 amp 240 volt outlet. I'm doing the same thing here in my cabin as I slowly rewire it.

UK appliances are available on the net. A 4kW tea kettle beats the hell out of a puny 1700 watt 120 volt version. Same with a commercial 240 volt toaster, coffee maker, etc. All I have to do is change the plug, getting rid of that UK abomination. Some of the e-stores sell appliances sans plug, aimed at the european market. The customer installs whatever plug is used in his country.

For a snow blower, why not make your own? Find one with a blown engine or buy a new one and sell the engine. Install a suitable electric motor and away you go. You can figure about 2/3s the HP of the gas engine is necessary for a normal high torque farm-duty motor.

If I were going to do that, I'd probably go a step further and use a 480 volt motor along with a 2:1 autotransformer at the house. That way the cord can be much lighter, something to think about when you're slaving away out in the white stuff.

Depending on what I could find and at what cost, I might even go with a 3 phase motor and VFD. The VFD will take single phase 240 as input and generate

480 three phase output and at whatever frequency you desire. Considering the cold operating environment, you could spin a smaller lighter motor faster and get more power than with a straight 60 hz motor. You could even have a "throttle" (a potentiometer) on the snowblower. Small VFDs (10 hp and less) are fairly easy to find used. For that matter, they're not all that expensive new.

John

-- John De Armond See my website for my current email address

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.

The issue is not the outlets available in my house [but I sometimes wish for 3 phase..].

Rather, it's the ready market of consumer appliances that would take advantage of them. That would require many houses to have them.

Get UK/commercial appliances, they're out there.

Yes like my Amana commercial RadarRange which is 4KW in 2.2KW out and has 3 HV magnetrons along with 3 each of the other necessary items (cap, diode, etc.). It even has a current transformer that tells the control board via current draw when the magnetrons are warmed up so that the timer doesn't start counting down until it is actually cooking. It has a standard NEMA

6-20 plug on it now and will pop a bag of popcorn in roughly 75 seconds without scorching it. I can tell you it sure beats the hell out of regular microwave ovens for most things. The only thing I still use the regular one for are items that involve liquids as the Amana tends to make them either boil over or boils out all of the water before the food is cooked.

Does this oven somehow injection-lock the magnetrons? Can you describe the (RF) plumbing?

Michael

| Yes like my Amana commercial RadarRange which is 4KW in 2.2KW out and has 3 | HV magnetrons along with 3 each of the other necessary items (cap, diode, | etc.). It even has a current transformer that tells the control board via | current draw when the magnetrons are warmed up so that the timer doesn't | start counting down until it is actually cooking. It has a standard NEMA | 6-20 plug on it now and will pop a bag of popcorn in roughly 75 seconds | without scorching it. I can tell you it sure beats the hell out of regular | microwave ovens for most things. The only thing I still use the regular one | for are items that involve liquids as the Amana tends to make them either | boil over or boils out all of the water before the food is cooked.

Will it operate on single phase power, like I have in my home?

A Lucas snowblower? It would leak oil, not work when damp, and plow down the wrong side of the driveway...

And want 50Hz...

Still thinking of the British Rail trains that wouldn't work because (to quote their PIO) "It was the wrong kind of snow"?

They'd be drooling over 60 Hz.

Can't comment on the microwave oven, though I suspect that it works the same as my gadget. A couple of years ago I built an EWF (electronic warfare) device to solve a particularly obnoxious boom-boom stereo problem. This guy would drive by my restaurant every evening on the way home from work. His stereo was loud enough to rattle things off my dining room shelves. Talking to him didn't work soooo...

My gadget used 4 1kw microwave oven magnetrons placed in a suitable waveguide one wavelength apart, the magnetron antennae simply protruding into the waveguide. With suitable use of tuning stubs, they phase-locked and the power added nicely. A quite large rectangular horn terminated the waveguide and matched it to the ether. I didn't bother with pulsed operation, as the first CW test was successful :-) Simon and Garfunkel's "The Sound of Silence" song came to mind.

I had the thing positioned in my dining room, aimed through the plate glass window at the area behind the stop sign. When he pulled up to the stop sign, the stereo a-thumping away, I touched the plate supply push button. Instant silence. Permanent silence. It killed his engine too, but it restarted.

John

-- John De Armond See my website for my current email address