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Current sensing <150 amps

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dkn

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Hello, I am seeking some information on current sensing up to 150 amps.

My task is to add a simple energy measuring device to a machine, the machine runs on 3phases of cause, but since my solution should be cheap and the result don't need to be super precise, I am thinking it would be okay to only use one current sensor and multiply it. The voltage will also be set at a constant value.

My question is if its easiest to connect a hall-effect sensor module to a pic or a wire coil type?

Since the installation should be easy and robust I was thinking something like this
Honeywell | Process Control | Sensors and Transducers | Current Transducers | Honeywell Current Transducers |CSNS300M

or

Honeywell | Process Control | Sensors and Transducers | Current Transducers | Current Transformers and Hall Effect |CSLA2DG

Could any of this work with just 10bit adc or should I do something else?

Thanks you for your time.

Regards
Dennis
 

3 phases refers to AC power supply, I guess. In this case, the measured quantities have to be processed by an averaging rectifier or true RMS circuit, unless you want to process the AC waveform in real time. In my opinion, current transformers or coreless di/dt sensors (rogowski coil) are preferable for AC current measurement.
 
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    dkn

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    Rey25

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it is far cheaper to go with a dedicated chip.
 

millwood ->
what of dedicated chip do you suggest?

But is it possible for me to use any of the items I posted a link to?

//dkn
 

there are tons of utility metering, smart (mcu-based) or hardware solutions, from many chip vendors. TI for example is a big player in smart metering, as is ADI.
 

For current sensing use MAX4081
For AC power metering use ADE7754 / 8
For 150A, you have to use a CT of usually 200/5 ration. These are fairly commonly available since they are used with almost every large electricity metering panel. Then on the secondary you can either use a shunt wire or another small CT.
 
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There have been various detailed suggestions, I don't know what you're missing.
 

I can't see how the MAX4081 is supposed to work with a CT really ? They just show a shunt resistor in the datasheet, and it makes to sense to me why that would be needed with a CT.
 

I read the MAX4081 suggestion to mean a DC measurement in contrast to a current transformer for AC. Apparently, some contributors didn't hear clearly that you have been talking about AC measurement. Of course, a shunt measurement can be applied for AC, too, but it's not reasonable in most cases, I think.
 

A very cheap method to make a CT is to use a small transformer and remove its secondary low voltage winding. Then use a single turn of think wire to serve as high current primary. The high voltage winding can now be used as current secondary with a suitable resistance as its burden (load, shunt).
 

Dennis,

Try using the Magnelab SCT-0750-150. This current transducer provides 0.333 Volt AC output at 150 Amps. If you are a student, the samples will be free of charge.

Rey
 

Can you please give me some more info on using hall effect flux sensors

thnks
 

All DC current transducers, that don't connect with a shunt to the current path are using hall effect sensors in some way. Either with an open magnetic path like the Allegro sensors or a magnetic core like the Honeywell and LEM current transducers. The latter divide into more simple direct measuring (or "open loop") devices and high preformance compensating current transducers. You'll find a lot of literature about their operation e.g. from LEM:
 

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