Read motor current with flex I/O

Hello all,

I have some motors and I wish to read their current. Is there a device or module that can measure these and convert them to a standard 0-10V or 4-20mA signal. I plan get my measurements into a flex rack eventually...any suggestions??

link to motor:

https://www.boschrexroth.com/en/us/...BE-00BFBBAD8475C541_ICS_97&sapCat=EL&o=portal


Thanks in advance!!

First...you will need a CT rated for the motor current.
You can get a CT that has 4-20mA out or you will have to buy a signal conditioner to change the standard 0-5Amps from CT to 4-20mA or 0-10V.

^ Like he said...

Oh..oh... Is that motor DC volts? That changes a few things...
Here is link for DC Current transducers..
https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/current_-a-_voltage_sensors_(ac_-a-_dc)/current_transducers/dc_current_transducers#

It is odd that a lot of new posts do not get moved to "New Posts". Why???

NetNathan said:

First...you will need a CT rated for the motor current.
You can get a CT that has 4-20mA out or you will have to buy a signal conditioner to change the standard 0-5Amps from CT to 4-20mA or 0-10V.

Click to expand...

Thanks! I will give this a try. I am very sure it is an AC motor as it is a synchronous motor. Do you know how I might be able to measure the torque as well??

It looks like that is a servo motor. Is it a an AC servo? Not a whole lot of information. If it is connected to a servo drive, does the drive have an analog output for current?

Measuring the current in an ordinary 3-phase across-the-line motor is often done with an overload relay that has those features, or with current transformers along with a transducer that outputs 4-20 mA or 0-10 V.

But the Bosch Rexroth motor you linked to is a synchronous servo motor, and is almost certainly being controlled by a servo controller. The current in a servo motor (or even most ordinary VFDs) varies far too fast to be measured accurately by a simple current transformer/transducer/analog device.

Look upstream of the motor for an "Indramat" or "IndraDrive" amplifier or servo controller. That's probably how you're going to be able to get feedback on the power output into another automation system, even if that's through an analog output <> analog input interconnection instead of a digital network.

Yes, the motor is being controlled by a Rexroth IndraDrive controller, specifically the CDB01.1C-SE-ENS-NNN-NNN-S1-S-NN-FW. From my research it appears to have 2 analog outputs (voltage and current). Although, I'm not sure what these outputs tell me. I've looked through the manual but I can't seem to find anything else that can help. I am wanting to also measure the torque of the motor but am unsure how to approach this...

Here's a link to the manual if someone wants to take a look: https://www.cmafh.com/WebsiteCatalo...B01 Project Planning Manual R911295012_08.pdf

Any help would be much appreciated!