Any one have trouble with Spectrum controls 1756sc cards locking up from high frequency noise using the j thermocouple applications??

I am using the spectrum control modules in a compressor station and having them lock up from the high frequency noise generated by the hei ignition system and static electricity from the wind too.

 

Too many 1756sc cards to tell whether it's thermocouple, or 4-20; single ended or differential, isolated or non-isolated. Nor is your required sampling rate provided.

So you get the generics:

Too reduce noise,

a) use twisted pair extension wire or copper. If the thermcouple wire isn't twisted pair, put one end in a vise, the other end in a drill and let the drill twist the wire.

b) Shield the cable or run it in conduit. Ground the shielding.

c) use a transmitter as most have low pass filtering built into them.

d) Is the AI card a high speed input, capable of sampling on short scans like 1mS or 5 mS?

e) I wonder if that level of noise isn't common mode saturating the input. Is the thermocouple grounded? Can you live with ungrounded?

f) wire runs cannot parallel AC lines.

Check out this article on reducing thermocouple noise from an engine test stand.
http://cp.literature.agilent.com/litweb/pdf/5989-7722EN.pdf