Why would "a bit of bondage" be locked?
- Thread starter david911cockburn
- Start date
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H
holmslaw
..
As I implied before, maybe you don't understand this concept of 'using power'. Generation of heat is what happens when current flows through a resistance. If the conductor had a zero temperature coefficient of resistance, then that would not result in any change of current - which is simply determined by Ohm's law.
Kind Regards, John.
I think I'll be out of this in less than half an hour - there is a limit to how much perverse 'fun'a man can take!
Kind Regards, John.
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John,
An increase in heat must be caused by an increase in power, therefore the resistance must be less.
Otherwise you are telling me that to make something hotter takes less energy, which obviously makes no sense.
An increase in heat must be caused by an increase in power, therefore the resistance must be less.
Otherwise you are telling me that to make something hotter takes less energy, which obviously makes no sense.
V= IR
P = (I x I)R
Do the maths!
P = (I x I)R
Do the maths!
What we're talking about is temperature, not 'heat' - and this is where you are wrong....
In the absence of heat losses (and that's what 'adiabatic' is all about - if you've ever heard the word) or any other complicating factors, temperature will carry on increasing indefinitely as a result of a constant current flowing - the is NO need for 'power' (or current) to increase for the temperature to rise.
The remainder of your argument therefore becomes incorrect.
Kind Regards, John
John,
The discussion is about allowing enough current to flow in order to automatically disconnect the supply within a given time, which is just about ohms law!
V = IR
P = (I x I)R
The discussion is about allowing enough current to flow in order to automatically disconnect the supply within a given time, which is just about ohms law!
V = IR
P = (I x I)R
I know what the discussion is about, but what is your point? Repeatedly making incorrect statements about basic principles obviously does not help your argument at all - nor even make it clear what your argument even is!
Kind Regards, John.
This is not a discussion. It's a series of statements from you in which you re-state Ohm's law ad nauseum and state simply how overcurrent protection works, interspersed with inchoherent prose full of words but bereft of meaning or direction.
And I still don't understand what point you are trying to make.
And I still don't understand what point you are trying to make.
P
Paul_C
No it doesn't. The current which flows during the fault is determined by the overall resistance of the circuit, not by the resistance of just the earth conductor. It's the reduction of that overall resistance of the circuit due to the fault which results in the increase in current.
John/echoes,
With the exception of Table 41C, Chapter 41 gives us lists of maximum loop impedance values. If those loop impedance values are met we know that enough current will be allowed to flow in order to automatically disconnect the supply within a specified time(s).
Table 41C gives us R2 values that that are less than the usual R2 values that you would expect to find as a part of the loop impedance values within the other Tables within Chapter 41.
Therefore in achieving the R2 values given in Table 41C, as they have a lower than expected resistance the current can be dissipated more quickly than would usually be the case, the cpc will not get as hot as it normally would and this will reduce the time it takes for automatic disconnection of supply to take place.
Therefore the R2 values (for fuses, MCB's where mistakenly added to this table in the 1960's) will guarantee a 0.4sec. disconnection time, whilst allowing you to increase the size of the fuse wire/cartridge for overload current purposes to as much as the nominal size on the front of the fuse carrier.
With the exception of Table 41C, Chapter 41 gives us lists of maximum loop impedance values. If those loop impedance values are met we know that enough current will be allowed to flow in order to automatically disconnect the supply within a specified time(s).
Table 41C gives us R2 values that that are less than the usual R2 values that you would expect to find as a part of the loop impedance values within the other Tables within Chapter 41.
Therefore in achieving the R2 values given in Table 41C, as they have a lower than expected resistance the current can be dissipated more quickly than would usually be the case, the cpc will not get as hot as it normally would and this will reduce the time it takes for automatic disconnection of supply to take place.
Therefore the R2 values (for fuses, MCB's where mistakenly added to this table in the 1960's) will guarantee a 0.4sec. disconnection time, whilst allowing you to increase the size of the fuse wire/cartridge for overload current purposes to as much as the nominal size on the front of the fuse carrier.
I'm afraid. I'm afraid, Dave. Dave, my mind is going. I can feel it. I can feel it. My mind is going. There is no question about it. I can feel it. I can feel it. I can feel it. I'm a... fraid. Good afternoon, gentlemen.
Paul,
The resistance of all of the other copper cables in the circuit is decreasing whilst the copper cpc is increasing???
John/echoes,
Heat costs money!
The resistance of all of the other copper cables in the circuit is decreasing whilst the copper cpc is increasing???
John/echoes,
Heat costs money!
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