Are current sensors rated for inrush or continuous current?

Automation and Control Sensors Transducers
1

I’m looking to use a non-intrusive current sensor to measure current going to a Brushed DC motor. The motor is rated for 349Amps continuous. Looking at the hall effect sensors (for example, similar to the type of the LEM LF 1005-S), are the current ratings rated for the inrush or continuous current? If the inrush current exceeds the rating, will the sensor unit fail? Or will it simply read at the maximum rating while the momentary inrush occurs?

2

danbmoreau

Thank you for contacting DigiKey , this part is rated for a maximum of 1500A measuring range per data sheet and manufacturer web site at a supply voltage of 24VDC , I do not believe a higher inrush current will harm this but I am not finding any info on the data sheet or manufacturer web site to show this . It may just show the 1500 A until the inrush goes away .

https://www.lem.com/sites/default/files/products_datasheets/lf%201005-s%20e.pdf

Thanks Craig

3

Hi danbmoreau ,

Exceeding the max current/voltage ratings may damage or degrade a current sensor and/or its accuracy over time. If pushed over the max rating, saturation may occur, which will lead to inaccurate, sometimes lower readings than what is actually present on the wire which may cause a false sense of ‘safer’ lower voltages or currents. This particular sensor does offer below per p.1 of datasheet:

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  • PN being primary nominal current RMS
4

Hello @danbmoreau,

There are additional consideration involving hysteresis to consider. Please see this article:

If you anticipate high peak current, you may want to investigate sensor degaussing. A resistive step-start may also be warranted to reduce the starting current.

Please let us know if you have additional questions.

Alos, kindly include a picture of your device as it sounds like an interesting project.

Best wishes,

APDahlen