Calculating Electric Potential Difference for Machinery Operation

AI Thread Summary
The discussion revolves around calculating the potential difference (PD) across cables connected to a generator outputting 240V, intended to operate machinery at 25A with a total cable resistance of 5.0Ω. The calculated PD is 115V, which raises the question of whether the machinery can operate effectively. Participants highlight that the machinery is assumed to draw 25A, but the specifics of its operation and load characteristics, such as being resistive or inductive, are not detailed in the problem. Understanding the nature of the machinery's load is crucial for determining its operational capacity at the specified current. The conversation emphasizes the importance of context in interpreting electrical problems.
andy.tsang
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Homework Statement


A generator has an output of 240V. It is intended to operate machinery some distance away. If the machinery has to operate on 25A and the cables carrying the current have a total resistance of 5.0Ω. find the PD across the ends of the cables. Will the machinery operate?


Homework Equations





The Attempt at a Solution


240 - PD = 5*25
PD= 240-125=115V

not sure if my answer is correct?

Thanks in advance!
 
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andy.tsang said:

Homework Statement


A generator has an output of 240V. It is intended to operate machinery some distance away. If the machinery has to operate on 25A and the cables carrying the current have a total resistance of 5.0Ω. find the PD across the ends of the cables. Will the machinery operate?


Homework Equations





The Attempt at a Solution


240 - PD = 5*25
PD= 240-125=115V

not sure if my answer is correct?

Thanks in advance!

Your result is correct.
 
Hi,
I'd like to know what is inside the machine that make sure the machine operate at 25A?
I mean how can we assure that the machine will operate at 25A.
 
anhnha said:
Hi,
I'd like to know what is inside the machine that make sure the machine operate at 25A?
I mean how can we assure that the machine will operate at 25A.

The question doesn't give enough information to specify precisely the makeup of the machinery. You have to "take it as given" that the machine draws 25A.

If you were to interpret the question to mean that the machinery is supposed to draw 25A at 240V, you might surmise that it is a resistive load of 240V/25A = 9.6Ω. But "machinery" often implies that there's a motor involved, which would imply that at least part of the load is inductive in nature (motors have windings to produce magnetic fields). If the load is purely inductive you could determine its impedance (reactance) if it is assumed to draw an apparent current of 25A at 240V.

How you interpret the given information depends upon the context of the coursework: course level and material covered in the course.
 
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Thanks, I wanted to understand the meaning of these given information in reality.
 
Thanks Gneill and Anhnha.
 
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