Temperature Sensor Type
Temperature Sensor Type
(OP)
I have to install a new temperature controller to a new tank that has to be heated with a electric resistance
The temp sensor has 3 cables: 2 white, 1 red
The seller of the tank is not responding
At first I thought that the sensor was a thermocouple but I am not sure because TC usually have only 2 cables
Any help on identifying what type of sensor do I have? Is it a RTD?

The temp sensor has 3 cables: 2 white, 1 red
The seller of the tank is not responding
At first I thought that the sensor was a thermocouple but I am not sure because TC usually have only 2 cables
Any help on identifying what type of sensor do I have? Is it a RTD?






RE: Temperature Sensor Type
RE: Temperature Sensor Type
R white_red=113,5 ohm
R white_white=2,5 ohm
I am guessing is a Pt100
RE: Temperature Sensor Type
xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Temperature Sensor Type
The whites are common, tied together at the RTD. You will need a 3-wire RTD controller. A symbol on the controller usually shows the schematical hookup clearly.
Then choose one of the two standards (US or European) and using an accurate thermometer at two different tank temps see if your guess was right.
Also consider what happens the day the electrical heaters stick ON, as it will happen someday. If the result can be destroyed product, burned animals(humans included), poison emissions, or fire, include an electrically separate second temp monitor/alarm/cutout.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Temperature Sensor Type
xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Temperature Sensor Type
RE: Temperature Sensor Type
Tank will be filled with H2SO4 (20% in water)
Process temp will be 75 ºC
Already bought the controllers with Pt100 / Cu50 / TC sensor input
Thanks to all
RE: Temperature Sensor Type
Boiling Sulfuric sounds really bad.
RE: Temperature Sensor Type
The controllers I have have 2 alarms (relay outputs) configuration which I can use to open a main contactor installed before the process contactors if temp reach a set value
RE: Temperature Sensor Type
I do suggest that if you're using a solid state relay or other semiconductor device to turn the heater on and off, that you have a good old fashioned mechanical contactor upstream of that device which is interlocked to open the heater circuit on a high high alarm. You have the alarm contacts to do that easily. All the semiconductor devices have at least some probability of an on-state failure, and if I remember correctly there is an electrical code requirement for such an interlock on process heaters for this reason. I could be wrong on that, but know that it is widely practiced and a very good idea to do, codes or not.
RE: Temperature Sensor Type
RE: Temperature Sensor Type
No. Good practice and codes universally require a separate 'controller' to drop out the energy supply in heating apps.
Using an alarm on the primary controller carries the enormous risk of common mode failure.
See NetNathan's post on this thread:
Link
http://www.plctalk.net/qanda/showthread.php?t=9733...
RE: Temperature Sensor Type
The number and robustness of layers of protection required to make something adequately safe depend both on the probability of the failure and the severity of the harm caused. The likely outcome of a fail on heater in an FRP tank is the failure if the heater coating leading to a rapid failure of the heater sheath, with the resistance wire going soon after that. That's a view from a distance though, and if the harm is likely to be more severe, the 2nd temp sensor and alarm trip module are warranted. But they are not absolutely required on every single heating application- that is an incorrect statement of fact.
RE: Temperature Sensor Type