What type of IEPE accelerometers can I connect to NI 9234?

[0206]

Hello.

I have a compactDAQ with NI 9234 to connect accelerometers. I want to perform some vibration measurements using it together the accelerometer in attachment (101.51-6D-2-M6).

Will the acceleromter work properly with NI 9234? Do I have restrictions about IEPE acceleromters for NI 9234?

Thanks,

Daniel

[Henrik_Volkers]

I would expect no problems, but the datasheet spec only declares 4mA excitation current (no current range found, unusual 😕 ) but your 9234 will provide 2mA (maybe more? ,check it in the detailed spec).

There are not so many IEPE electronics manufacturers, and all IEPE sensors I had worked with also run with 2mA. However ask vibrasens to be sure.

[0206]

Henrik,

Thanks for your answer.

In the first part of the datasheet Vibrasens it is written "It uses the industry standard ©ICP / ©IEPE / ©LIVM 2-wire voltage transmission technique with a 4 mA standard constant current supply." If you see the electrical specifications the power requirements are: constant current +2 to +10 mA and voltage +22 to 28 vdc. I am understanding the 4 mA as a maximum of current.

At this moment by biggest doubt is about the voltage: in the accelerometer datasheet  the required voltage is +22 to +28 vdc. The NI 9234 datasheet specifies 19 V of IEPE compliance voltage (maximum value). Will the accelerometer work properly under these conditions? Should all IEPE the acceleromters have less than 19 V of power requirements in order to work correctly in NI 9234?

Thanks a lot,

Daniel

[Henrik_Volkers]

Yea, you are rigth about the current, didn't take the time to look closer at the sensor spec. 😉

The 9234 will provide 19V @ 2mA  but that is no problem, since the AC input range is (only)  +-5V , so there is enough headroom unless your sensor will provide more than about 5V amplitude.

See Page 22 of the user manual

[0206]

Henrik,

Thanks a lot for your help.

I also have found some more information about this subject in "Why Do Some IEPE Sensors Specify “Excitation Voltage”?" in NI knowledgeBase.

Together with your help now I have a better understanding of this subject.

Regards,

Daniel

[0206]

Hello.

I have the same NI module and accelerometer (101.51-6D-2-M6).

My doubt is about the voltage output of the accelerometer. This voltage is in the range [-8;+8] Vdc while the input range for the module is [-5;+5] Vdc.

Will I cause any damage to the module, due to overvoltage, working with this accelerometer?

Thanks for your help.

[Henrik_Volkers]

The max overload voltage is noted in the spec. / manual 

I don't expect any damage, however check in with the manual.

[Henrik_Volkers]

Your IEPE sensor will (usually) provide a +-9Vmax signal with a 10V (+2V) bias. No problem with for the NI9234, it will 'overrange' but no dammage should occur.