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workshop addition

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dsaint

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i just finished my exams at uni and now i am going to devote myself to electronics. and my first project i think i'll start working on is an isolated supply system by maily using two scavanged torrodial transformers from 420v to 45 couple 1:2 2:1 to isolate the suply and then feed an elcb and two mcb to isolate to power rails for my workshop what do you think? and i want to ask a simple question but which i cant find a way two work around this is if you can build a diy variac?

regards
 
From my experience it has always been cheaper to buy a 5 or 10 amp variac fom a surplus place and enclose it in a box with fuses and outlets. Finished units from somebody like Staco Energy are often over $300, a surplus variac can often be had for $75 or less.

For an isolation transformer it is fairly cheap to buy what is known as a control class transformer, wired to provide 240 / 480 to 120 / 240 , and use the split windings to hook it up as a 120 to 120 isolation transformer. These transformers come with 4 terminals on each side with split windings, so the output volage/VA rating of the transformer can be chosen.
 
great

yeah i know about the variac thing because i read it ofter in elect mag but here in malta unfortunately we do not have an electronics surplus store and that poses a bit of a problem to the hobbyst and student I will tr and get one by mail order if nothing comes across on the net and about the transformer i'll try you suggestion even tough i have both torrodials at hand but i cud spare them for a better usage
regards
 
If you isolate your supply, an elcb will no longer work as it requires a current to flow to earth in order to trip.

Mike.
 
Pommie said:
If you isolate your supply, an elcb will no longer work as it requires a current to flow to earth in order to trip.

That's the whole point!.

The reason for an elcb is to disconnect the supply in the case of one particular error condition - which is usually from live, through your body, down to ground, and through the ground back to neutral.

Isolating the supply removes the conventions of live and neutral, and prevents you getting a shock to ground from either wire - so there's no need for an elcb, it's already far safer!.
 
Nigel,

That was my point, he said he was going to isolate the supply and fit an elcb. I was pointing out that the elcb was pointless. Rereading my post, I can see that it can be read the other way round.

Mike.
 
Pommie said:
That was my point, he said he was going to isolate the supply and fit an elcb. I was pointing out that the elcb was pointless. Rereading my post, I can see that it can be read the other way round.

Sorry Mike, I hadn't noticed his original elcb mention.
 
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