Hi All,

For my project here I need to measure DC current going to a number of motors, max. would be about 10A each. The measured values will be sampled by a NI Labview setup. Can anyone recommend a fairly inexpensive hall
effect or other type of sensor that I could use to measure the current going through the power wires?

Thank you to any responders,
FW

 

What is the maximum voltage on the DC power lines?

 

The pump I'm using takes 24V.

 

How about a resistor? Can't beat it for price.

John

 

The are quite nice current sensors out there suitable for NI cans. You can use these google words "current sensor dc".

 

You can use a 0.005 ohm resistor and a current shunt monitor like the INA214 family from TI. This family has a common-mode voltage of 26V.

The INA214 family are differential amplifiers. You can read about a power supply current measurement and common-mode voltage, as well as errors, in this article:

The Differential Amplifier Common-Mode Error – Part 2 - Power Supply Output Current Measurement with a Differential Amplifier

Since the INA family has integrated matched resistors you don't need to be concerned about the common-mode errors.

 

I second jpanhalt's suggestion of a shunt resistor. The only catch is that you need a differential input unless one side of the resistor is tied to ground. Use about a 1/2" long chunk of 16 gauge Nichrome wire and you can make your own 0.01 Ω resistor that drops 100 mV at 10 A (it will be dissipating 1 W at 10 A, so it's gonna be warm).

 

Use about a 1/2" long chunk of 16 gauge Nichrome wire and you can make your own 0.01 Ω resistor that drops 100 mV at 10 A (it will be dissipating 1 W at 10 A, so it's gonna be warm).

The alternative is to buy one from Digikey ($0.5 ... $2).

 

Thanks guys, excellent responses. I think I'll try using a simple shunt resistor.

Thanks again,
FW