24 VDC to a thermocouple

Hello all,
The electrical contractor in the plant we are starting-up connected by mistake the wire corresponding to the thermocouple to the 24 VDC terminals. This was at the transmitter, where there are 2 terminals for the thermocouple wires and 2 for the wires from the PLC.
Do you think this could have damaged the thermocouples?

Thank you!

Was the 24vdc present? Did it blow a fuse? If not then you are probably ok. Test it.

The thermocouple would look like a short to your 24vdc.

Thermocuoples are higher resistance than pure copper wire, but not much. Like Mickey says, it's nearly a dead short across the power supply. Most power supplies have some sort of shut down protection against dumping huge current into a short circuit.

Even if a long run of thermocouple wire pushed the circuit reistance up high enough to not trip off or output limit the power supply, the thermocouple and its lead wire would act as a heater.

I, too, doubt that the T/C elements were damaged.

Thank you very much for your responses!

OK, I will give the opposite view. Yes the power supply will probably be protected against a dead short but in the time it takes to detect the dead short you can still get current flowing. I have a customer who connected thermocouples direct to a 4-20mA loop, it killed the thermocouples. The power supply here was limited to 250mA and short circuit protected. So I would say that it is very likely that your thermocouples are dead.

I believe that flowing currents through the power supply would change the characteristics of the thermocouple calibration , for me I see it will work after this short but with a different reading , which has to be recalibrated