The USB TC-01 is displaying incorrect temperatures when operating near an induction heater.

[Echo_52Hz]

I am trying to measure the sample's temperature for PID control. However, I've noticed that the USB TC-01 consistently provides inaccurate readings when the induction heating is activated. Specifically, the USB TC-01 malfunctions, displaying a temperature of only 22.4°C each time the induction heater's output current reaches 80%. This issue is evident in the attached image. Notably, this malfunction is not stable and may also occur when the heater output current is lower than 80%. Besides, I also observed that the malfunction occurs, or becomes more frequent, when I have both the USB-6001 plugged into the computer and operate the USB TC-01 simultaneously while the induction heater is on.

Additionally, I've observed a significant increase in the thermocouple reading while the induction heater is on, even though the thermocouple itself is not malfunctioning. Images 2 and 3 display incorrect readings (100+ °C), while the correct temperature of 50 °C is shown when the induction heater is switched off.

[santo_13]

Can you share more about the location of the induction heater and the TC?

If the TC is in electrical contact with the induction heater, you need to electrically isolate them as you're injecting a high potential into the USB-TC system if not well grounded.

[Echo_52Hz]

Sorry for the late reply. The location of the induction heater and the TC is shown in the attached figure. The red colour represents the induction heater coil, black represents the sample, and blue represents the thermocouple probe. Note that the sample does not physically touch the heater coil. However, the wire from USB-6001 to the heater makes electrical contact with the heater for output control.

May I ask how I should electrically isolate the TC and USB-6001, as both are connected to the computer using USB? Apologies for the possibly basic question. Thanks for your patience and assistance.

[santo_13]

How is the USB-6001 connected to the heater coil? Some SSR?

What happens when you power the heater coil directly without using 6001 to control it, do you still observe the thermocouple fluctuation issue?

Can you provide a better diagram of all the components involved?

[Echo_52Hz]

Sorry, could you clarify what SSR stands for? Currently, the USB-6001 analogue output is connected to the heater power supply for controlling the heater power output.

Yes, I attempted to power the heater without using the USB-6001, and the USB TC-01 malfunctions, displaying a temperature of only 22.4°C each time the induction heater's output current reaches 80%, as shown in IMG_1 in the question at the beginning.

The diagram with all the components involved is attached in this reply

[santo_13]

SSR - Solid State Relay is typically used to control heating elements using PWM.

Could you share the exact details of all involved hardware? the type of TC, heater power supply, etc.?

[Echo_52Hz]

yes, there is a SSR to carry out the heating process. However, the heater has a built in start/stop button to control the heating process.

Sure, the all hardware are listed below:

- Heater power supply and heat station are UPT-Series Ultra-Heat SM.

- DAC card is USB-6001.

- Type k thermocouple

- Thermocouple module is USB TC-01

- The sample is an aluminium bar