Find Constant of Proportionality for Current Transducer

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Discussion Overview

The discussion revolves around determining the constant of proportionality (K) for a current transducer based on its datasheet. Participants explore how to derive the relationship between output voltage and current, focusing on the equations provided in the datasheet and the implications of nominal current.

Discussion Character

  • Homework-related
  • Technical explanation
  • Exploratory

Main Points Raised

  • Participants seek to understand the equation Vout = K*I and how to identify the constant K from the datasheet.
  • There is confusion regarding the meaning of nominal rms current (Ipn) and how it relates to the actual current being measured (Ip).
  • One participant suggests that Ipn is a baseline current that can be set by wiring the current path differently, with options for 5, 10, or 20 Amps.
  • Another participant expresses the need to simplify the equation for use in LabVIEW, indicating they can only use Vout and Ip as variables.
  • There is mention of Vref being 2.5V, which is part of the equation for Vout.
  • Participants discuss the possibility of measuring actual current and voltage versus relying solely on the datasheet for information.

Areas of Agreement / Disagreement

Participants generally agree on the need to clarify the role of Ipn and Vref in the equation, but there remains uncertainty about how to apply these concepts practically and whether the datasheet provides sufficient information.

Contextual Notes

The discussion highlights the limitations of the datasheet, with participants noting that it may not provide clear guidance on how to set up the current transducer for accurate measurements.

Who May Find This Useful

This discussion may be useful for students working on electronics projects involving current transducers, particularly those needing to interpret datasheets and apply theoretical concepts in practical applications.

boreilly
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Homework Statement



The output voltage of a current transducer is proportional to the the current it is detecting/reading. i need to know the constant of proportionality. apparently I should be able to find this on just on a datasheet.

Homework Equations




Vout= K*I. what is K?

The Attempt at a Solution



on the datasheet i do have the equation:
Vout= Vref +/- 0.625*(Ip/Ipn)
Ip is the current being measured(fine)
Ipn is the nominal rms current(which means?)
and it has Vref too.

how do i get it in the form of an equation that i can put in labview. I can only have two variables, the Vout, and the current being measured.
I would have understood nominal current to be the current that a component can take, but it may not be the actual current drawn by the load. but here the Ipn is +/-20 A while the
Ip has a range of +/-60 A. so do i just have the Ip/Ipn part as Ip/20 for the entire range?
 
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boreilly said:

Homework Statement



The output voltage of a current transducer is proportional to the the current it is detecting/reading. i need to know the constant of proportionality. apparently I should be able to find this on just on a datasheet.

Homework Equations




Vout= K*I. what is K?

The Attempt at a Solution



on the datasheet i do have the equation:
Vout= Vref +/- 0.625*(Ip/Ipn)
Ip is the current being measured(fine)
Ipn is the nominal rms current(which means?)
and it has Vref too.

how do i get it in the form of an equation that i can put in labview. I can only have two variables, the Vout, and the current being measured.
I would have understood nominal current to be the current that a component can take, but it may not be the actual current drawn by the load. but here the Ipn is +/-20 A while the
Ip has a range of +/-60 A. so do i just have the Ip/Ipn part as Ip/20 for the entire range?

Can you post a link to the datasheet?
 
boreilly said:
dammit can't believe i forgot that

http://datasheet.octopart.com/HXS-20-NP-LEM-datasheet-120813.pdf

i know i could measure the actual current and voltage on the circuit but apparently I should be able just see if on the datasheet which would be easier

Okay, that helps. Definitely not a great datasheet, but I think I see what is going on now.

The Ipn number is a constant, either 5 or 10 or 20 Amps as a baseline for the measurement. you set Ipn by wiring the high-current path differently -- see the wiring diagrams near the end of the datasheet. Once you've wired the current path for 5 or 10 or 20 Amps, that is the reference current that you use in that equation. And Vref is just 2.5V.
 
Ok. I can work with that. Some other students in a previous year built the circuit so i just need to establish what they set as the base current. thanks.
 

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