How to shield NI-USB TC01 from EMF/Noise

[Bpatel]

Hello,

I'd like some suggestions on how to properly protect my NI USB TC01 from EM/Noise interference that i'm using for testing purposes with my labview code

Environment: Inside a home-made thermal chamber that will go from -40C (via liquid nitrogen pump controlled by my program) and upto 115C (via heat gun controlled by my program). Nearby this chamber will be a motor that is spinning a shaft inside the chamber(with the product i'm testing mounted)

Problem: Whenever i start up my large motor(20HP, 1750 RPM 480VAC) with my motor controller, my temperature readings from the  NI TC01 USB module go haywire. I'm assuming the electromagnetic field generated from the motor is the cause of this interference in my TC01 readings..whenever the motor is OFF, temp readings are perfectly stable..

Are there any suggestions the community might have on how to shield and protect the NI-TC01 USB from this type of interference?

I'm trying to isolate the module as far away as possible from the motor but i'm not having any luck. 

Should I try to enclose the module in some kind of case? is there something i can do to the input terminals of this device to draw away the noise/interfence?

I have tried a ferrite choke around the USB cable that is connected to the module but that didn't solve it either so it seems like I got the issue pinpointed to the input terminals of this TC01..

I should have read the detailed specs of this module a bit better..there is a disclaimer saying EM interference will affect the measurement accuracy of this device since the input terminals of this device are not protected from such interference/noise..

Any thoughts on this matter would be appreciated!

[johnsold]

You need to determine how the interference is getting into the TC01 before you start thinking abouy how to fix it.

The first thing to look at is ground (or earth) connections. Determine where and how every device in the system is presently grounded. Motor and motor controller. Thermal chamber. Device Under Test. Thermocouple. USB TC01. Computer. Liquid nitrogen pump and plumbing. Heat gun and controller. Adn the twelve other things you have not mentioned wut which are there.

Grounding problems are often the issue as opposed to fields.

Lynn

[Bpatel]

Thanks I'll look into that

I will mention my laptop is completely isolated (via isolation transformer) from the major systems/circuits in play

The tc01 and other DAQs are of course connected to this laptop so I believe I have my main control parts isolated from the motor..

Do I need to look into possibly shielding my thermocouple? It's doesn't have a ground wire since there's no shielding on my thermocouple wire..

What's the best way to ground the ni tc01 and thermo couple ?

[Henrik_Volkers]

I don't know how the TC is looking like...

I assume a mainly  magnetic coupling..  

1. reduce the field in the chamber:  A massiv plate of Iron with a hole  (or even a slit) between motor and chamber can greatly help.. BTDT.. (My 'motor' was a shaker, however :D)

2. the TC cable should be twisted!! , every little loop (even between the two wires) will catch magnetic fields.  The way how you place the wire (avoid movements) in the field affect the EMC.

instead of the USB thing hook up the TC to a scope and look at the output (you can abuse the sound input of your PC ... AT OWN RISK 😆 )  By twisting the wire you can find a position with minimum interference....