The E-Chargers - Can they be used in a small bench?

[1960flh]

John, when you say you have 40amp circuit is it US or UK 240 volt service? As there are easy solutions to reduce your current draw.

Example the Surplus Center motors draw 7 amps at a full load (unrestricted) at 120V 60hz, two of these motors wired in series will require 240V but only draw 3.5 amps load (unrestricted). These motors are universal and will have little or no effect by the difference in service frequency US 60hz or UK 50hz. I think there are several thread on this topic on the forum for further research.

JMT

Rick

[jsa]

[1960flh]

[color=#000000]JSA;

Ohms law I= E/R (current = Voltage/Resistence)

Thus if you use two 120v motors in series across the 240v circuit the current draw across two motors is halved for a total of 7amp draw for two motors vs 7amps for one on a 120v circuit. For rough numbers lets say the motor looks like 17+- ohms, at 120v ac that would be 7amps draw, two of these in series would look like 34 ohms and at 240 volts that would still be 7 amps. Now we are talking AC so this just for rough numbers.

You said

[Tony]

For anyone that has a serious shortage of electrical power, how about driving a big air blower with a petrol engine ?

The few horsepower required should be no trouble at all for almost any old engine that runs. With a bit of thought it cold be made to run fairly quiet.

[jsa]

[quote="1960flh"][/quote]
[color=#000000]Rick,

[quote]You said

[jsa]

[Tony]

But seriously though, a small four cylinder car engine hooked up to a battery, radiator, and fuel tank could drive either a large industrial pressure blower, or an automotive supercharger, and require no mains power at all.

For people renting, or living way out in the middle of nowhere, it may be the easiest or lowest cost option.

[jsa]

[color=#000000]This is a reply to Rick, whose post has vanished. Bruce it seems the forum has a bug in it.


Rick,

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I got your point


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I hope you understand why I was pointing out the ability to use equally efficient 120v motors in series to reduce the overall current draw.



Ok, we are on the same wavelength with motors / volts / amps / power / air quantity.

Quote
please don

[1960flh]

John,

I see this is an important issue to you and I am not trying to argue your point to me its about understanding learning and growing. If you research on Duty Cycle on Welding type equipment you will find Duty Cycle has NOTHING to do with current draw at the feed circuit. Your example of a 15 amp feed 80 amp welder works as follows. Watts law Power in the Primary = Power in the Secondary, 15amps X 250 volts = 3750watts, a standard welder will utilize a secondary open circuit voltage of around 50 volts un loaded thus 3750/50=75 minimum amp potential on open circuit. Because during the arc stage secondary voltage may drop as low as 20 to 25 volts welding current potential could be as high as 150 - 185 amps without affecting the feed. It is the operating temperature of both the transformer/triac (depending on conventional or solid state) and the thermal capacity of the rectifiers used that limit duty cycle. Duty cycle came about when welding companies decided to wind some transformers out of aluminum. Here is what Miller has to say about Duty Cycle.




So in your concept solution something has to act as the over current heat absorber during the duty cycle and I am not sure what that is supposed to be, That is why I have replied as I have. I apologize if I have offended you as it is not my intention.

Rick

[jsa]

[Tony]

Unfortunately for what we are doing, the maximum available mains supply current is what ultimately spoils our type of fun.

At least I am in Melbourne Australia, and blessed with three phase 240v. I don't know if we have anyone here from Japan, but I believe they have only 100v 60Hz over there.

It then comes down to the harsh reality of more mains amps or greater flow bench blower efficiency. Fifty percent is fairly readily achievable, that is mains watts converted to air watts.

So work out your efficiency, and then decide what is realistic.

[jsa]

[Tony]

[86rocco]

Don't rub it in boys. Last Monday it was -29C where is was and right now, it's -10 C and snowing like a mofo here.

[bruce]

Lets all go play with Tony's flowbench!! Serious Roadtrip!!