63A 3 phase socket
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battery charger is in a container so needs to be easily disconnectable, hence plug.
Yes, i was thinking about earthing which is why i mentioned MCB type and earthing type earlier.. I will work out R1 + R2 for the cable in a minute
john..
john..
Ok...
So the cable is a 10mm 4 core, Obviously the armour will be used as CPC..
R1 + R2 for the cable is 0.2488
Ze for the supply is..
TNS 0.8
TNCS 0.35
This will give a Zs of..
TNS 1.0488
TNCS 0.5988
And that mind you, is BEFORE you allow for the increase in R1 + R2 under fault conditions due to cable heating...
Might be a few snags here.. [apart from, not sure about if it is TNCS, taking it 45 metres outside the equipotential zone of the building though..]
So the cable is a 10mm 4 core, Obviously the armour will be used as CPC..
R1 + R2 for the cable is 0.2488
Ze for the supply is..
TNS 0.8
TNCS 0.35
This will give a Zs of..
TNS 1.0488
TNCS 0.5988
And that mind you, is BEFORE you allow for the increase in R1 + R2 under fault conditions due to cable heating...
Might be a few snags here.. [apart from, not sure about if it is TNCS, taking it 45 metres outside the equipotential zone of the building though..]
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Well like i said, there are a few snags here.
Zs is going to be 1.0488 for TNS and 0.5988 for TNCS and, having allowed for cable heating under fault conditions, for a 63A "B" curve you want a max Zs of 0.583 and for a "C" curve, 0.292..
There is no doubt about it, a 63A WILL take you over the required Zs so an RCD will have to be used to achieve disconnection times required in the event of an earth fault. What about L/L or L/N faults though?? Disconnection times for these could well be longer than 5 seconds..
Ok, so there is no requirement as to disconnection times whatsoever [APART from in the event of an earth fault] but the amount of heat a cable can withstand in the event of a fault, is, as far as i know, based on 5 second disconnection times.
If you go over this, then you are on your own!! The values for "K" in the adiabatic equation are all based on 5 seconds so far as i know, but does this just apply to a CPC?? Not sure, i am only a welder you see, and it is a long time since i fiddled about with any electrics..
john..
This is still discussing a 63A socket outlet correct?
The client wants a 63A socket, design the circuit with a 63A lb and have done with it.
Also, do we know it's going to be supplied from an mcb? If it's a BS88 db the Zs issue will likely disappear.
The client wants a 63A socket, design the circuit with a 63A lb and have done with it.
Also, do we know it's going to be supplied from an mcb? If it's a BS88 db the Zs issue will likely disappear.
Zs measured at 0.17.
No idea, wasn't asked to look at that, but container is not a permanent feature, so guess would count as being more or less the same as using an extension lead from your house into garden.
Without knowing the site and layout of the installation I can't really comment but is the container earthed/bonded to the main installation?
Absolutely no idea - it's classifed equipment and I wasn't shown the batteries / chargers. Batteries get charged about 2 or 3 times a year. Most of the stuff is shipped world wide, and arrives / leaves in shiping containers. For safety reasons the batteries are charged during the day external to the building. I know what you are getting at @Sidney but they have their own electrical engineering staff.
live testing at the socket, mind you my test gear is due calibrating. and swa is terminated to steel trunking that most of the cabling for the industrial unit is run in, so live test is probably benefitting from parallel earth paths
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That reading would be impossible as R1 + R2 for the cable is higher than that.. Not sure what is happening there./. I expect one of the others will know though..
john..
The R2 value will be incredibly low due to the mass of metalwork the armour is attached to. Disconnect the armour at the load and redo the test will give an actual R1+R2 value. This is what he should be doing anyway.
I've had this many times, where R1+R2 gives higher figure than the Zs value - confused the hell out of me the first time it happened. Might have forgotten to zero my leads mind you, but my test gear is usually withing 0.5 Ohms even then.
I've always been of the opinion that the live test is more important as this is what the cct will see in operation - but that's my opinion! R1+R2 is more interesting to me when there are multiple joins along cct eg 10 sockets, where there is far higher chance of a dodgy connection and high resistance at some point along it's length.
Hi Rob i was thinking if it could be due to the armour being earthed at both ends, but i understood it was terminated to a plastic socket and the charger was a free standing thing..
Anyway, you are not going to get Zs that low unless the DNO transformer is next door to you.. [or you have like a 200A supply.]
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