Calculating Electric Potential Difference for Machinery Operation

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Homework Help Overview

The discussion revolves around calculating the potential difference (PD) across the ends of cables connected to a generator with an output of 240V, intended to operate machinery that requires 25A. The total resistance of the cables is given as 5.0Ω, and participants are exploring whether the machinery will operate under these conditions.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants attempt to calculate the PD using the formula related to voltage, current, and resistance. Questions arise regarding the machinery's operation at 25A and the assumptions made about the load type, whether resistive or inductive.

Discussion Status

The discussion includes attempts to clarify the relationship between the generator's output, the current draw of the machinery, and the resistance of the cables. Some participants express uncertainty about the correctness of their calculations, while others provide insights into the nature of the machinery and its operational characteristics.

Contextual Notes

There is a noted lack of specific information regarding the machinery's internal workings and how it maintains a current of 25A. Participants highlight the need to interpret the problem within the context of their coursework, which may influence their understanding of the load type.

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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