http://cgi.ebay.com/5000-w-Watts-Vo...063088519QQihZ020QQcategoryZ294QQcmdZViewItem
Could i use one of these to change american 240volts to 120volts? It would act as an isolation transformer. American has +120 & -120. Europe just has 240.
The only thing i am worried about is how much power it will use at idle. It will only use a few watts if there is nothing connected to the other side right?
What else should i add, varesistors, fiter caps, ect.
Could i use one of these to change american 240volts to 120volts? It would act as an isolation transformer. American has +120 & -120. Europe just has 240.
The only thing i am worried about is how much power it will use at idle. It will only use a few watts if there is nothing connected to the other side right?
What else should i add, varesistors, fiter caps, ect.
ak_47_boy said:
Hi,
I think in US, the AC voltage is 117VAC, But if you open the main switch box, probably you can get 2 phase of 117V. thus, you can get 234VAC out with 2 live, therefore, you should put 2 current leakage cct breaker at each rail for your safety. or better to get an electrician to connect it for you. It's dangerous if you are not familiar with the AC switch box.
If you use transformer for step up/dn convert ion, there are two types of transformers, one is auto, another is isolated. auto is the one carries live, isolated is not carries live, this type is more safe due to no linkage to supply line live.
The standby current of auto is far less than isolated one. The power loss will depends on the quality of the transformer, what we call Eddie current.
Varesistor is a component that varies it's resistance by change of voltage. and filter cap is to used to smooth out ripples, Capacitor used to across the AC line is to correct the angle phase of the AC power. What we called Vector correction. this type of cap usually is oil can cap, non polarized.
Make sure what you needed? step up or down? and precaution of high Voltage!!!
Good luck
Sounds good.
So if i need exactly 117VAC i need a autotransformer? For that step down tranny on ebay do i connect one phase to hot on the transformer and the other phase to neutral on the transformer and neutral to ground?
If the transformer is 98% efficient then 2% is lost in eddy currents, 2% of 5000W is 100W idle? Does a 2% loss sound about right for this transformer? I guess i should get a smaller transformer like 2000W is cut down on power loss.
Oh and do i need a scope to find the correct capacitor across the lines? Moter run cap?
So if i need exactly 117VAC i need a autotransformer? For that step down tranny on ebay do i connect one phase to hot on the transformer and the other phase to neutral on the transformer and neutral to ground?
If the transformer is 98% efficient then 2% is lost in eddy currents, 2% of 5000W is 100W idle? Does a 2% loss sound about right for this transformer? I guess i should get a smaller transformer like 2000W is cut down on power loss.
Oh and do i need a scope to find the correct capacitor across the lines? Moter run cap?
ak_47_boy said:
Hey. Guy:
From the location stated, You are in Canada, Right? The AC source is already 117Vac, why you want 220 dn to 110v ???
Unless you want an isolation from live! If so, then you must get an isolated tranny. I don't know the one you wanted from Ebay, is an isolated one. you must check before you buy it. But remember, you want the one is 110v to 110v isolated.
For connection, one side connected to AC power line, secondary float the two wires up. Thus you can achieve an isolated power source.
PS: autotransformer is lived, be cautioned. Usually transformer on idle consumes only a few watts, a hundred is too much, good for junk yard!
Good Luck, and Happy holidays.
Perhaps he wants equally load both legs of the split-phase 120/240VAC mains and achieve isolation at the same time. 
Steve
Steve
N-Channel said:Perhaps he wants equally load both legs of the split-phase 120/240VAC mains and achieve isolation at the same time.
Steve
Exactly, i think.
The 240/120 trannys are just so cheap on ebay. A 30amp 120/120 isolation transformer would cost alot. I don't think the quality of the transformer matters much in this case as long as leakage is not massive. What would happen if i did this? Explosion of boiling copper?
An externally hosted image should be here but it was not working when we last tested it.
drop the nutral, then you shoulb be good to go.
When using 120 -120(180 phase) the difference between them two is 240, if you put the nutral in there you get 120 - 0 - 120.
For what you want to do, you don't need the nutral, and the way you have it hooked up makes the isolation part usless.
When using 120 -120(180 phase) the difference between them two is 240, if you put the nutral in there you get 120 - 0 - 120.
For what you want to do, you don't need the nutral, and the way you have it hooked up makes the isolation part usless.
Ok, thanks. Could i hook neutral to ground?
edit: how many uF should the oil can cap that goes across the secondarys be? Would puting then across the primary and across the secondary be good?
edit: where does the filter cap go? Like the oil can?
edit: how many uF should the oil can cap that goes across the secondarys be? Would puting then across the primary and across the secondary be good?
edit: where does the filter cap go? Like the oil can?
I am going to follow this:
http://www.geocities.com/jonrisch/surge.htm
I would like to add in the oil can caps if it would help. Maby just across the primary of the transformer? How do i wire a oil can on? How big should it be?
http://www.geocities.com/jonrisch/surge.htm
I would like to add in the oil can caps if it would help. Maby just across the primary of the transformer? How do i wire a oil can on? How big should it be?
I have all the parts on there way exept for some motor run or oil caps. What size and where do they go?
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