Phase converters

I hope that this NG might have the knowledge on phase converters...I have
an old 3ph jointer that I am running off a converter...runs fine...never a
problem...which leads me to consider a 3 ph space heater...I am unsure if
the converter would work as well with heating...since the watts are
higher...would I have to have a high amp breaker run the converter? A bad
idea?
Also there is a Reed Prentis lathe 18 swing
available locally...can I convert this beast to woodworking?
thanks
Reply to
ted scott
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Knowing that USA V & A are slightly different in phases etc., I hesitate to make any sweeping statements, but a basic resistive heater would have a unity power factory which 'should' help your converter with other, lower power factor loads like motors.
Why convert it, can't you use it as it is and just get the necessary attachments made up for wood? We had a local patternmaker in our factory estate shut down at the beginning of this year, and a huge 'proper' woodturning lathe with floor standing toolrest, bed toolrest, loads of nice attachments etc was almost given away for about $170 because there was no interest in it.
That was a specialist wood lathe that must have cost a small fortune when new.
I don't think we kept the pictures for the ebay adverts but it was a superb machine.
Peter
Reply to
Peter A Forbes
ted asks, plaintively,
"...since the watts are higher...would I have to have a high amp breaker run the converter? A bad idea ..."
Yeah, ted, a "bad" idea, esp. since you didn't provide enough information to allow anyone to formulate a reasonable answer. Also you seem to be suffering under the idea that a solution to electrical problems might be to just connect things to a larger breaker. Be aware, breakers don't "run" anything - they only provide a limiting source of current for whatever is connected to them. An overlarge breaker will only degrade the safety factor. Suggest you seek the services of a qualified electrician.
Bob Swinney
Reply to
Robert Swinney
Assuming the heater has 3 separate elements wired in delta or wye configuration, you could rewire them in parallel and run off a single phase supply. If the motor is 3 phase, just run that from the phase converter. Martin
Reply to
Martin Whybrow
... which leads me to consider a 3 ph space heater ... I am unsure if the converter would work as well with heating ...
Resistive loads, such as heaters and kilns, should be run off of single-phase, or true three-phase, not converted three-phase.
No point in providing a third wire at a phase angle which the load doesn't care about, anyway.
Rewire for single-phase, balancing the resistance elements are best as possible, across the two lines.
Reply to
Peter H.
Phase converters do not ADD power to any appliance. Meaning that unless you were given the worlds best space heater for free on 3 phase, you are better off getting a single phase heater. Otherwise, you actually LOSE power in the converter.
Reply to
Scott Moore
"Lose" in this context is a bit misleading. Power is never lost, only mis-placed, so to speak. The conversion efficiency is less than perfect in the rotary converter, so some of the power will appear as heating in the device overall.
However since the final application is indeed space heating this means that a three phase heater run off a rotary converter will produce exactly as much heat as a similar rated one run off of single phase power - if the converter shares space with the heater itself, that is.
I don't think I personally would go that way though.
Jim
Reply to
jim rozen
You're assuming the phase converter is as efficient as coupling that heat to the air as the heater is. ;-)
Reply to
Scott Moore
It is. I absolutely can assure you that the thermal power out of a rotary converter is equal to it's electrical losses, over a one hour period.
If it weren't, the thing would be molten inside three hours.
Jim
Reply to
jim rozen
Not really, the efficiency in transferring the heat to air only affects how hot the phase converter will be.
Dan
Reply to
Dan Caster
Jim sez:
"> It is. I absolutely can assure you that the thermal power out
Is there some valid technical reason you pegged your answer to a rigid time basis? Or are you merely trolling for Gary, whom we've not heard from in some time?
Bob Swinney
Reply to
Robert Swinney
On 22 Nov 2004 05:53:00 -0800, jim rozen vaguely proposed a theory ......and in reply I say!:
remove ns from my header address to reply via email
sound....?
Reply to
Old Nick
Pure experimental experience. I know that the temperature of my crawl space equibrates after about one hour, when I'm running my converter.
I also know that the converter's loss is about 200 watts, and there's about 40 pounds of copper and iron in the motor. If I were going to make a furnace to melt 40 pounds of material like that, using only a 200 watt heater, it would take a while. In this case I defined 'a while' as three hours. SWAG and all.
Of course that would require one to insulate the motor really well and remove the cooling fan.
The only experience I've ever had with somthing like that was when somebody (not me!) tried to warm up a dewar by putting a 60 watt trouble light into the neck. They came back after three hours and the fiberglass neck of the dewar was nearly on fire. I think the trouble light didn't fare too well at all.
Honestly I enjoy Gary's responses. I would *never* put an off-the-cuff SWAG here just to troll for him. Honest!!
Reply to
jim rozen
Jim sez: " > Honestly I enjoy Gary's responses. I would *never* put an
Aw, Jim! Go ahead and troll a bit for Gary. I sort of enjoyed some of his stuff also. He was good as long as you kept him off electrical subjects, esp. *phase relationships*. You could quote a text book verbatim, and he'd still argue!
Bob Swinney
Reply to
Robert Swinney
Well I think he's in pretty good company on that around here!!
Jim
Reply to
jim rozen

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