Balanced Power Supply
#1 Balanced Power Supply
I have gotten hold of a 3kva toroid with 120-0-120 secondaries and fancy giving a balanced supply a go. This was sold to a chap on another forum by a hi fi company, he was told it was a prototype, and the proper version was silly money, about three grand I think.
Anyway, he was sold it with no protection at all, no fuses, no MCB, no RCBO or anything at all - for which they should be lined up against the wall and shot IMHO - he's not of a technical bent, so didn't know any better.
I'd like to do this properly, so to that end have bought a suitable enclosure. I'm also going to buy a 16A MCB for the primary, and a double pole 16A RCBO for the balanced secondaries. He mentioned it can trip the supply on switch on, so I have bought an SL 32 surge limiter rated at 1R 30A, and I'll mount a double socket on the box too, to plug everything in to.
I'll wire the two secondaries through the RCBO, and run the CT to the mains earth.
The question is, have I missed anything? I assume the RCBO will work just the same as in a conventional circuit, and all will be hunky dory and safe?
Anyway, he was sold it with no protection at all, no fuses, no MCB, no RCBO or anything at all - for which they should be lined up against the wall and shot IMHO - he's not of a technical bent, so didn't know any better.
I'd like to do this properly, so to that end have bought a suitable enclosure. I'm also going to buy a 16A MCB for the primary, and a double pole 16A RCBO for the balanced secondaries. He mentioned it can trip the supply on switch on, so I have bought an SL 32 surge limiter rated at 1R 30A, and I'll mount a double socket on the box too, to plug everything in to.
I'll wire the two secondaries through the RCBO, and run the CT to the mains earth.
The question is, have I missed anything? I assume the RCBO will work just the same as in a conventional circuit, and all will be hunky dory and safe?
#2
A diagram might help us, Ali. I think the thing to bear in mind, as you know, is you now have two lives with respect to earth. Don't you guys do this sort of thing in the power industry? I mean its not conceptually a million miles from protecting a 3 phase set up, in safety terms is it?
Surge protection is a good idea, definitely might be a fuse blower as that big iron core charges up.
Andrew
Surge protection is a good idea, definitely might be a fuse blower as that big iron core charges up.
Andrew
Analogue, the lost world that lies between 0 and 1.
#3
I have a DC blocker board somewhere about you can have to throw in the primary as well if you like Ali.
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#4
Remember that MCBs etc are sold at various surge ratings to prevent switch-on trips. Most domestic ones are "C" rated. Motor start ones (what you need) are "D" rated. You may have to get them from your local electrical factors (the sheds normally only stock domestic "C" rated circuit breakers)...
hth
hth
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#5
Aye, I looked at that, but looking at the 3kva balanced trannie on the Airlink website, they use "C" rated breakers.nickds1 wrote:Remember that MCBs etc are sold at various surge ratings to prevent switch-on trips. Most domestic ones are "C" rated. Motor start ones (what you need) are "D" rated. You may have to get them from your local electrical factors (the sheds normally only stock domestic "C" rated circuit breakers)...
hth
#6
That would be great thanks Nick, I was going to get one of those IEC sockets with built in blocker.Nick wrote:I have a DC blocker board somewhere about you can have to throw in the primary as well if you like Ali.
#7
It's the balanced bit throwing me a little, not sure if the RCBO will work correctly.Andrew wrote:A diagram might help us, Ali. I think the thing to bear in mind, as you know, is you now have two lives with respect to earth. Don't you guys do this sort of thing in the power industry? I mean its not conceptually a million miles from protecting a 3 phase set up, in safety terms is it?
Surge protection is a good idea, definitely might be a fuse blower as that big iron core charges up.
Andrew
Here's the sort of thing I'm thinking about-
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#8
I made the mistake of Googling!
But yes seems has to be a 2-pole cut-out. Some think a 240V device is OK others think must be for 110V specifically.
But yes seems has to be a 2-pole cut-out. Some think a 240V device is OK others think must be for 110V specifically.
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#11
Those RCBO are just two coils (solenoids?) one pulls and one push at a switch, I think, so they look for current not voltage so it doens't matter what the relative potential is, .i.e single ended or balanced does it?Ali Tait wrote:It's the balanced bit throwing me a little, not sure if the RCBO will work correctly.Andrew wrote:A diagram might help us, Ali. I think the thing to bear in mind, as you know, is you now have two lives with respect to earth. Don't you guys do this sort of thing in the power industry? I mean its not conceptually a million miles from protecting a 3 phase set up, in safety terms is it?
Surge protection is a good idea, definitely might be a fuse blower as that big iron core charges up.
Andrew
Here's the sort of thing I'm thinking about-
Do I have that right?
Analogue, the lost world that lies between 0 and 1.
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#12
I think so too, L & N currents must be equal, and none to earth.
Most of the Google searched arguments were about whether the RCBO disconnects both L & N, but I think they normally do don't they?
I mean on ours if you connect N to E it trips out (guess how I know ), so it must disconnect N as well as L.
Most of the Google searched arguments were about whether the RCBO disconnects both L & N, but I think they normally do don't they?
I mean on ours if you connect N to E it trips out (guess how I know ), so it must disconnect N as well as L.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
#13
Andrew, yes I believe so, but wasn't sure, hence the post. I think as long as they will see a difference in each leg if there is a fault on one, and trip, I'll be happy.
Mike, from what I've read, both legs need to trip as you could have a fault one one leg, and the fault current could circulate via the other leg, hence the need for both to trip.
Mike, from what I've read, both legs need to trip as you could have a fault one one leg, and the fault current could circulate via the other leg, hence the need for both to trip.