- Thread Starter
- #141
what exactly is that?
there are 2x 15A fuses ... each one per one toroidal transformer.
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Circuit breaker - which to choose
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radix
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Regarding the fuses, doesn't the back panel say "T12.5A @ 220-230V"? It seems like 15A is the wrong fuse. I believe it's supposed to be a slow-blow fuse too. You might want to check with a MF tech to see if you have the correct fuses. I'm going by a photo of the PSU I found on the internet, so maybe I have the wrong PSU.
There are several ways to get a grounded outlet. One way is to have a 2-conductor (insulated) wire plus a ground, which is usually bare copper. Neutral is tied to an earth ground at the point of entry, usually by an 8' copper rod pounded into the ground. Another way is to have only a 2-conductor (insulated) wire and tie the ground of the outlet to neutral, then somewhere -- usually at the point of entry -- neutral is tied to ground. There are several other ways.
Having a 2-conductor with separate ground means the ground normally has no current on it, because nothing is shorting to ground. Without current, there is no voltage drop. So the metal chassis, say of a giant amplifier, will be close to 0V relative to ground.
If you have only a 2-conductor outlet with ground tied to neutral at the outlet, then there is current on the ground. This means there will be a voltage on the ground, and thus on the metal chassis. usually, the neutral resistance is low and current modest, so the voltage is small. But if you have a toroidal (or 3) pulling giant inrush current, there will be a brief period where that voltage on the ground (and thus the chassis) is not so small.
Electrical distribution networks (the utility) and house wiring have many ways to do things and sometimes the methods are mixed over time. Please consult a local electrician about any changes.
radix
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I missed this post when I posted the last response. Having a 2-conductor with separate ground wire to the outlet is, I think, the safest way of doing it. I believe that's called PE+N, but the abbreviations are confusing. If he says it's 2 conductor + ground, each separate, that's it.
My understanding is the PSU is 1200W (say 6A @ 230V). It has 2x 12.5A fuses (@ 230V). So that sounds like a single 25A circuit would be OK. You might still need the slower circuit breaker. Assuming its a dedicated run just for the amp and there's no other outlets on that breaker. If you will have other things sharing the branch, I'd go for the 2x25A and use a split outlet or other option. That amp is a beast of a PSU.
I assume that you love this amp and will not replace it. otherwise, a current model amp likely would not have the same inrush issue and probably would not need the outlet re-wired. (of course, depends on the amp). I don't know how much the rewire costs versus a new amp where you are.
- Thread Starter
- #144
sorry my fault... yes 12.5A
- Thread Starter
- #145
he said ... that there is TN-C and then he will be able to make separate PEN, ie 3 cables to wall socket (each will be separate) ie i assume separate ground.
- Thread Starter
- #146
was 4k amp or something like that ...
i believe rewire will be 500e hopefully dont have another 4k for a new amp.- Thread Starter
- #147
oh, i assumed 16A CB with slower curve ie cat C will be fine... so do i have to go for 25A for that amp?
Thanks!
radix
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I don't know how much the PSU will draw on start up. You could ask MF.
The CB has to be sized for the wiring. The electrician can tell you what sizes CB could be put in depending on the wire size. The PSU is labeled 1200W (6A), but it likely has a much higher startup current.
Speedskater
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The primary task of the Protective Earth/Safety ground conductor is to trip a circuit breaker in the case of a Ground Fault (Short circuit).
True there is continuity to Planet Earth, but it has little to do with day-to-day AC power quality.
True there is continuity to Planet Earth, but it has little to do with day-to-day AC power quality.
radix
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There was a fair bit of talk about GFCI in this thread. I just came across this story of the development of a GFCI chip in the 1970s. It also has some anecdotes about testing ground faults on grad students to figure out the right response times!
NOTE: This is a plain "http://..." link and your browser might not like it.
GFI
www.idea2ic.com
NOTE: This is a plain "http://..." link and your browser might not like it.
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radix
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It's a plain http:// link, not https://, so your browser is complaining. I added a note to my post about that.
Very nice link! I used.>>>
GFI
www.idea2ic.com
Ima read this thoroughly...
radix
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I've been sucked into other posts on that site. Lots of cool stuff.
Fascinating at the least! I read the first 2/3 and then skimmed and scanned and was amazed. An amazing read!
"The present schematic for the LM1851 is shown above.
The design philosophy was to connect the coil which
is really a 1:1000 turn transformer directly across
the two inputs to an Op Amp. This would make the 1000
turns of the secondary see a virtual ground. As a result,
the ground fault sensing coil would be in current mode
such that a 5mA imbalance in line current would deliver
5uA of current into the summing node of the Op Amp.
The faults signal was now handled as a current to
be processed to match the UL timing spec."
Just woW!
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