Electrical design problem calculation

[psjaivansh]

A single-phase radial circuit is to be installed to supply a number of socket outlets. The source of supply is 230 V, 50 Hz with a declared value of external earth fault loop impedance, Ze, of 0.8 Ω. The cable selected is PVC-insulated and incorporates the circuit protective conductor. The conductor impedances with a conductor temperature of 20 C are as follows:
Phase conductor resistance = 7.41 mΩ/m
Circuit protective conductor resistance = 12.10 mΩ/m
The temperature coefficient of resistance of the conductor material is 0.004 per C, at 20 C.
The circuit protective device will be a Type C MCB, data for which are provided in Table A1, and a 20 A rating is specified .

how to calculate maximum circuit length for this circuit? State any assumptions made

[TD="colspan: 7"] Table A1:Maximum earth fault loop impedances in Ohms for Type C MCBs for disconnection times of both 0.4 s with U o 230 V and 5 s.
[/TD]

[TD="width: 14%"] Rating (amps)
[/TD]
[TD="width: 14%"]10
[/TD]
[TD="width: 14%"]16
[/TD]
[TD="width: 14%"]20
[/TD]
[TD="width: 14%"]25
[/TD]
[TD="width: 14%"]32
[/TD]
[TD="width: 14%"]45
[/TD]

[TD="width: 14%"] Zs (ohms)
[/TD]
[TD="width: 14%"]2.40
[/TD]
[TD="width: 14%"] 1.50
[/TD]
[TD="width: 14%"] 1.20
[/TD]
[TD="width: 14%"] 0.96
[/TD]
[TD="width: 14%"] 0.75
[/TD]
[TD="width: 14%"] 0.53
[/TD]

Assume that the installed circuit has the maximum length calculated in (i) above. If, in the future, the circuit needs to be extended, suggest two ways that this might be done, and the circuit length that could be achieved.

 

[telectrix]

before anyone else says it, have a go and post your answer/s. then we can see that you've made a try, and put you right if necessary.

 

[ian.settle1]

We are not here to do your homework, work it out and tell us what you think the answer is and we will teel if you are correct or not

 

[Silly Sausage]

He's just copied and pasted an exam question.
Hasn't even bothered to ask for the answer...brilliant!

 

[Sharpend]

What exam is this for?
What thoughts do you have on how to solve it?

 

[telectrix]

hint: it will be longer than one of E54's earth rods.

 

[trev]

Fairly straight forward calculation that you have all the relevant information to enable you to perform mate. What part of it are you struggling with?

 

[ian.settle1]

Fairly straight forward calculation that you have all the relevant information to enable you to perform mate. What part of it are you struggling with?

The whole question by the looks of things

 

[drew35]

"Assume that the installed circuit has the maximum length calculated in (i) above. If, in the future, the circuit needs to be extended, suggest two ways that this might be done, and the circuit length that could be achieved. "


Read more: http://www.electriciansforums.net/e...design-problem-calculation.html#ixzz2OkbfYBEN

The answer is - two ways to extend a circuit. The right way and the wrong way.

Length achieved- What ever you'll pay me for...

 

[telectrix]

Length achieved- What ever you'll pay me for...



said that to the wife. no wonder i'm skint.

​

 

[Loges1504]

I have a concern with volt drop and Zs.

Could someone confirm that this is correct as i am not getting this output and i am not happy with it.

 

[telectrix]

7 year old thread resurrecrion, is rthat a record?