Understanding current measurement on an irregular waveform

In summary, the conversation discusses using a Keithley 2400 source meter to generate a 120Hz AC signal for resistance measurements on semiconductor materials. The Keithley 2000-20 multimeter is used to validate the input current, with a 1.01 ohm resistor and a sweep from 1A to -1A. The meter measures .94A during the sweep and 1.01A when sending 1A without sweeping. The difference in magnitude and the impact of using an AC current are questioned, as well as the presence of dwells at 0A and a 7% error. There is also a request to set the source to a 2App square wave with a -1A offset.
  • #1
tempneff
85
3
I hoped to use a Keithley 2400 source meter to generate a ~120Hz AC signal by outputting a 2-point sweep from 1A to -1A on an infinite trigger. The waveform image is attached below.

The end goal is a resistance measurement for bulk semiconductor materials, we prefer AC measurement to avoid thermoelectric drifts. To validate my input current I am measuring AC amperage through a verified 1.01 ohm resistor with a Keithley 2000-20 multimeter.

The meter measures .94A AC during the sweep. If I send 1A without sweeping and read DC current, it measures 1.01A; as expected.

I'd like to better understand the difference in magnitude. How is the measurement impacted by an "AC" current. Is there something problematic math-wise by not sending a sine wave.

current_waveform.PNG
 

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  • #2
Why are there dwells at 0A when switching polarity? Is that maybe where the 7% error is coming from?
 
  • #3
Could be. I think it is inherent to the timing of the source meter. I have the delay set to zero, but we know that isn't possible.
 
  • #4
Is there a way to set the source to be 2App square wave with a -1A offset, instead of it being the two point sweep? I'm not familiar with that generator...
 

FAQ: Understanding current measurement on an irregular waveform

1. What is current measurement on an irregular waveform?

Current measurement on an irregular waveform refers to the process of measuring the flow of electric current over time on a waveform that does not follow a regular pattern or shape. This type of measurement is commonly used in electrical engineering and other fields to analyze and understand the behavior of complex electrical systems.

2. How is current measured on an irregular waveform?

Current can be measured on an irregular waveform using specialized equipment such as an oscilloscope or a current probe. These tools allow for precise measurement of the amplitude, frequency, and other characteristics of the current on the waveform. The measurements can then be analyzed and interpreted to gain insights into the behavior of the system.

3. What are the challenges of measuring current on an irregular waveform?

Measuring current on an irregular waveform can pose several challenges. One of the main challenges is accurately capturing the varying amplitudes and frequencies of the current. Additionally, noise and interference can also affect the measurements and make it difficult to obtain accurate data. Another challenge is interpreting the data and understanding the complex behavior of the waveform.

4. Why is it important to understand current measurement on an irregular waveform?

Understanding current measurement on an irregular waveform is crucial for several reasons. First, it allows for the analysis and troubleshooting of complex electrical systems. By measuring and interpreting the current on the waveform, engineers and scientists can identify any issues or abnormalities and make necessary adjustments. Additionally, understanding current measurement can also aid in the design and optimization of these systems.

5. What are some applications of current measurement on an irregular waveform?

The measurement of current on an irregular waveform has many practical applications. It is commonly used in the fields of electrical engineering, electronics, and telecommunications to analyze and design complex circuits and systems. It is also used in medical devices, aerospace equipment, and renewable energy systems, among others. In summary, current measurement on an irregular waveform is an essential tool for understanding and optimizing various electrical systems and technologies.

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