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AC current sensor compatibility CR800 + AM 16/32


Benjamin.vial Dec 28, 2020 04:18 AM

Hi,

I'm looking for a AC current sensor just like the CS11, but significally smaller, to monitor 2.5mm² wires.

Campbell sell only the CS11 from a CR8459 current transformer, but I see on the constructor website (crmagnetics) there is a CR8401 model, smaller. So multiple questions :

1 - Is this compatible on a CR800 ? I'm not sure what specifications are to be worried of.

2 - How many sensor of this type can be plugged on a CR800 (if we consider there is no other sensor)?

3 - Can we increase the number of this type of sensor with a AM 16/32 plugged on the CR800 ?

Thanks,

bye


JDavis Dec 28, 2020 01:14 PM

The input range on a CR800 is -5VDC to +5VDC. As long as the sensor output is within that range, you can read it on a CR800. If you are looking at raw current transducers, you have to add a resistor to change the output from a tiny current to a voltage. Looking in the CS11 manual, you will see a diagram showing how Campbell Scientific adds a resistor.

Each transducer needs 1 SE channel. There are six such channels on a CR800. 

A multiplexer could be used. Be aware that it takes time to do channel switching, so will limit how fast you can sample the full set of sensors.


Benjamin.vial Dec 30, 2020 06:35 AM

Hi,

thanks for your answer.

About the +-5Vdc input voltage range I've looking on the specifications (from CRMagnetics) of the CR8459 and can't tell if that can be used. It works of course, as CSI send it on their website, but can't see on the doc where to understand it.

As I cant see where to know what is the minimum current seen (but I see the max). On CRMagnetic's doc it seem that the CS11 is a "revenue grade current transducer", because the CS11 can measure 200A maximum. But the 8401 don't exists on the grade... So I think to buy the CR8401 for general purpose to see <10A AC current, and some CR8420 to see <50A for power supply monitoring applications.

And about the multiplexer I think make a scan period about 10 minutes so no worry about the response delay.

Other question, with CR8401 instead of the CR8459, can I use the ACPower function in CRBasic editor ? I've looking for the resistance information in the CS11 documentation but can find it too ...

Sorry, it seem I don't really understand how to choose the sensor in this case !

(here is the link to the crmagnetics doc for the CR84XX series : https://www.crmagnetics.com/Assets/ProductPDFs/CR8400%20Series%20Specification%20Page.pdf)


JDavis Dec 30, 2020 10:22 AM

I usually recommend selecting sensors from Magnelab. It is clear what output signal the sensor has when ordering.

https://www.magnelab.com/product-category/ac-current-sensors/

0.333VAC output signals work well with the ACPower instruction.

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