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240V 20A extensiopn cords......

nadogail

Well-known member
Joined
Jan 23, 2009
Messages
32,069
Location
Coronado, CA
Regarding the relative efficiencies of different types of phase inverters, I am not in a position to comment with any real degree of competence.

For that reason I offer a full money back guarantee on any advice I offer. My advice is worth exactly what you pay for it. Send a self addressed stamped envelope and your full refund will be enclosed.

Rotary phase converters can be made at home from boneyard parts. I once sent someone $5 for the following information.

Basically you need to get a three phase motor that is rated at 150% of the horsepower of the three phase motor you intend to run. A little larger would not be bad.

You hook up 2 of the 240 supply leads to your Three Phase Converter, using an appropriate disconnect. For purpose of illustration we will call them the A and B leads.

That leaves you a third converter input, we will call the C lead, that will be connected to either the A or B input through a momentary contact and an appropriately sized series connected starting capacitor . The capacitor should an AC Capacitor and rated for full AC line voltage and be about 12 mfd per converter horsepower.

Converter output will be connected to the A, B, and C terminals of the phase converter, and run through a three phase disconnect to your intended load.

To start the converter, close the supply contacts and close the momentary contact. The converter should start to rotate. After about 3/4 of a second open the momentary contact and the converter will come up to speed.

After the three phase converter comes up to speed, close the output switch to your 3 phase load.

I realize that this is a third world solution and the three phase motor may not develope full facet rated horsepower, but most machining operations do not require full motor output. but if you have more time and desire than money we can learn from those less fortunate.
 
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bczygan

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Joined
Nov 4, 2009
Messages
22,002
Location
DETROIT! Arsenal of Scrappers
Well, I received the standard 240V 20A plug I had ordered off Ebay, so decided to hook up the cord I picked up yesterday. Couldn't get the diameter of cord through the plastic bushing on the plug, so left the bushing off for now. This is temporary anyway.

Decided to hook up to the compressor. Not easy. Had to remove a shroud, a copper line, a fixed air hose and the two gauges. Then rotate and swivel the pressure regulator to get some small access to the connections, or at least two of them, on the bottom. The existing cord is missing a bushing where it goes through the hole in the enclosure, so need to do something there. So I'm in the middle of it all. Think I'll put a new fixed hose on it and change the oil. Going to use some synthetic. It could also use filters cause they're missing. Will also flush the tank and put a shut off valve on that. Plus the hub on one plastic wheel is damaged, so time for HF. I've also seen people fabricate little racks for accessories and to wind hose and cord onto, besides using the handle.

Bill
 

sberry

Banned
Joined
Jun 18, 2005
Messages
35,747
Location
Brethren, Michigan
1 foot or 100 the heat is the same per foot. But back to Bill. The breaker may be larger than it needs to be to protect against thermal if the load is calculated as to not overheat the wire but needs to be small enough to still provide short circuit. This is the same way as appliances that use a 16 cord with 15 amp end allowed on a 20 amp circuit.
 

theoldwizard1

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Joined
Feb 22, 2011
Messages
43,351
Location
SE MI
1 foot or 100 the heat is the same per foot. But back to Bill. The breaker may be larger than it needs to be to protect against thermal if the load is calculated as to not overheat the wire but needs to be small enough to still provide short circuit. This is the same way as appliances that use a 16 cord with 15 amp end allowed on a 20 amp circuit.

6-50 is the standards welder plug, regardless of the size of the welder. I will bet most of the "hobby" shops/garages have them wired to 20A-30A breaker with wire to match.

I never thought this (oversized plug) was a real "safe" practice, especially when the cord is sized for a much smaller load. This means that if the welder is taken to a shop that has a real 50A circuit (breaker and wiring) and the welder is used well beyond its duty cycle range or there is some kind of internal problem, the cord is now your fuse ! :shocking:
 
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