# Find Constant of Proportionality for Current Transducer

• boreilly
In summary, the output voltage of a current transducer is proportional to the current it is detecting, with the constant of proportionality represented by K. This value can be found on the datasheet and can be calculated using the equation Vout= Vref +/- 0.625*(Ip/Ipn), where Ip is the measured current and Ipn is the nominal RMS current. Vref is a constant value of 2.5V. The Ipn number is a reference value that can be set by wiring the high-current path for 5, 10, or 20 Amps, as shown in the wiring diagrams on the datasheet.
boreilly

## 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?

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.

## 1. What is a current transducer and why is it important to find its constant of proportionality?

A current transducer is a device used to measure the electrical current flowing through a circuit. The constant of proportionality is a value that relates the input current to the output voltage of the transducer. This value is important because it allows us to accurately calculate and monitor the current in a circuit, which is crucial for the proper functioning of electrical systems.

## 2. How is the constant of proportionality determined for a current transducer?

The constant of proportionality for a current transducer is typically determined through calibration. This involves applying known currents to the transducer and measuring the corresponding output voltages. By plotting these values on a graph, the slope of the line can be calculated, which represents the constant of proportionality.

## 3. What factors can affect the accuracy of the constant of proportionality for a current transducer?

Several factors can affect the accuracy of the constant of proportionality for a current transducer. These include temperature, linearity of the transducer's response, and external magnetic fields. It is important to carefully calibrate and test the transducer to account for these factors and ensure accurate measurements.

## 4. Can the constant of proportionality change over time for a current transducer?

In some cases, the constant of proportionality for a current transducer can change over time due to factors such as wear and tear or changes in the circuit it is measuring. Therefore, it is important to regularly calibrate and recalibrate the transducer to maintain accuracy and account for any changes.

## 5. How does the constant of proportionality differ for different types of current transducers?

The constant of proportionality can vary between different types of current transducers depending on their design and technology. For example, a Hall effect transducer will have a different constant of proportionality than a shunt resistor transducer. It is important to understand the specific type of transducer being used and its corresponding constant of proportionality for accurate measurements.

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