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Member
king9sun
Posts: 8
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Please help. NI USB-TC01 has problems with Type S thermocouple

I tested the NI USB-TC01 with a type S thermocouple in a furnace. The furnace temperature was set to increas to 1300 oC. But during the furnace heating up over 1100 oC (shown on the furnace controller), the reading of NI USB-TC01 started to drop down to 800 oC even the real temperature was kept increasing. I used another thermometer to read from the S thermocouple.  The thermometer's reading showed the same temperature as that from the furnace controller.

 

 

Also I noticed the reading of NI USB-TC01 kept dropping from room temperature to 0 oC before the furnace started running.

 

When the NI USB-TC01 connecting with a  type B thermocouple, there is no such problems. Is there any special care needed to Type S thermocouple using NI USB-TC01?

 

Thanks,

 

Xu

Member
Peter-R
Posts: 67
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Re: Please help. NI USB-TC01 has problems with Type S thermocouple

[ Edited ]

Hi Xu, 

 

Have you configured your device to acquire a temperature measurement from an S-Type thermocouple? 

 

How did you use a thermometer to read the S-thermocouple? As thermcouples output a small voltage... 

 

Were you reading from the S-thermocouple channel when the temperature dropped to zero? 

 

Thanks,

 

--
Peter Rifken - Field Engineer & Business Manager
Boston / North New England & Maine
Member
king9sun
Posts: 8
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Re: Please help. NI USB-TC01 has problems with Type S thermocouple

Hi Peter,

 

Have you configured your device to acquire a temperature measurement from an S-Type thermocouple?

 

Yes.

 

How did you use a thermometer to read the S-thermocouple? As thermcouples output a small voltage...

 

as the same as NI USB-TC01, I have a digit thermoeter which can be connected to the S-thermocouple. When the furnace temperature was 1300 oC, the thermometer showed 1300 oC but the TC01 showed 813 oC

 

Were you reading from the S-thermocouple channel when the temperature dropped to zero?

 

Yes. 

 

Thanks,

 

Member
Peter-R
Posts: 67
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Re: Please help. NI USB-TC01 has problems with Type S thermocouple

Thanks, can you confirm that you experience erratic behavior viewing readings in both Measurement & Automation Explorer and LabVIEW? From this point on, we should work in Measurement & Automation Explorer to be safe. 

--
Peter Rifken - Field Engineer & Business Manager
Boston / North New England & Maine
Member
king9sun
Posts: 8
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Re: Please help. NI USB-TC01 has problems with Type S thermocouple

Thank you , peter,

 

 

 

Yes I experience the erratic behavior viewing readings in both the data loging saftware with the USB-TC01 and LabVIEWI. This erratic behavior can be repeated   over 1100 oC. There is no any problem using B-thermocouple with the same setup. 

 

Thank again.

 

Xu

Member
Peter-R
Posts: 67
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Re: Please help. NI USB-TC01 has problems with Type S thermocouple

It looks like the problem is with the S-Thermocouple itself. Does this thermocouple having shielding or other grounding considerations? Do you have another S-type thermocouple you could test on your DAQ device? How about another thermocouple type other than "B" and "S"? 

--
Peter Rifken - Field Engineer & Business Manager
Boston / North New England & Maine
Member
king9sun
Posts: 8
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Re: Please help. NI USB-TC01 has problems with Type S thermocouple

I tested the Ni USB-TC01 with other 2 S-type thermocouple ( only wires) . They had the same behavior. I also tested with K type with no problem.

 

 

Member
Peter-R
Posts: 67
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Re: Please help. NI USB-TC01 has problems with Type S thermocouple

I found your excel spread sheet and can see the behavior you are describing. What is the manufacturer of your thermocouple? 

--
Peter Rifken - Field Engineer & Business Manager
Boston / North New England & Maine
Member
king9sun
Posts: 8
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Re: Please help. NI USB-TC01 has problems with Type S thermocouple

Thank you. Peter.

I don't know the  manufacturer of the thermocouples. Just maybe from Omega.

 

Thanks,

 

 

Member
WillPwr
Posts: 135
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Re: Please help. NI USB-TC01 has problems with Type S thermocouple

Hello, Xu!

 

This is Will, I'm taking over this issue from Peter, who you were speaking with before.

 

In response to your original question, there shouldn't be any special considerations when using S-type thermocouples, other than changing your device configuration (which you mentioned you've already done).

 

Since you're dealing with higher temperatures, it's possible that these or previous tests exceed the maximum temperature range of the S-types that you are using, especially since the B and K types seem to be working fine. Without knowing the manufacturer of the S-types you're using, it's difficult to say since you can't check the allowable range.

 

Is there a particular reason that you need to use S-types, or are you merely concerned with having a functional thermocouple? From looking at Omega's website as an example, it looks like the maximum temperature ranges for their thermocouples are rated as follows: (keep in mind that this range will differ for different manufacturers)

 

K-type: – 200 to 1250°C

S-type:       0 to 1450°C

B-type:       0 to 1700°C

 

Given that you're evaluating temperatures approaching 1200C, I'd recommend using B-types vs. K and S-types, especially since you may end up completely exceeding the maximum range for the K-types.

 

You also mentioned that you tried two other S-type thermocouples with no success. First, could you clarify what you mean by "only wires?" Second, were these new thermocouples, or have they been used in previous high-heat experiments?

 

When I've seen this behavior in the past, it's been due to a malfunctional thermocouple. So, if there is a convenient way to obtain a new S-type thermocouple, I'd recommend that. In addition, you might try updating your USB-TC01 firmware drivers (if you haven't already), as outlined in this document.

 

Please let us know if this helps, and we'll happily assist you if more questions come up.

 

Thanks, Xu!

 

-Will

 

 

 

 

 

 

 

 

 

 

Will Hilzinger | Switch Product Support Engineer | National Instruments