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Wiring of Thermocouple module to Thermocouple in field

Created by: Arunabha at: 8/8/2007 3:18 PM (5 Replies)

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8/8/2007 3:18 PM	Rate (0)
Arunabha Member Joined: 5/25/2007 Last visit: 9/5/2007 Posts: 6 Rating: (0)	Please help me?? What is the standard practice of wiring a thermocouple in field and the thermocouple I/O Module inside RIO Panel? Should we use the panel inside wiring ( From I/O Module to terminal ) a compensating cable also?? what about the terminal ? should be a normal terminal or a compensating terminal (if Any!!) please help me with a standard solution Regards Arunabha

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8/8/2007 10:42 PM	Rate (0)
Dorftrottel? Silver Member Joined: 8/10/2006 Last visit: 8/13/2024 Posts: 298 Rating: (29)	It depends on whether you need to be able to have the T/C's plugged in (quick replacement of throw-away modules, movable thermocouples, etc.) For permanent installations, I recommend wiring from the thermocouple head directly to the thermocouple module channel terminials. (No input blocks in between). This minimizes corrosion problems, helps simplify calibration Each terminal block, even the correct type, is a possible source of noise. If you do use terminal blocks, they must be the same type or composition as your thermocouples. Otherwise, each termination becomse a cold-junction point, and creates an offset to the actual temperature. (I have seen errors >40° C)

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8/9/2007 2:26 AM	Rate (0)
GJohn Posts: 112 Rating: (10)	I would also recommend wiring from the thermocouple head directly to the cold junction. (Noterminals in between). You should always use compensating cable between the thermocouple cable and the cold junction. The cold junction can be at your panel with the Analog thermocouple I/O module or it could be a seperate panel in the field with copper conductors wiredto the Analog thermocouple I/O module. Wire another thermocouple or RTD and locate this inside the cold junction panel to compensate for the cold junction temperature. If I have only a few thermocouples I would wire each of them to a 4-20mA converter which also compensates for the cold junction temperature. I would then use an analog current input module. This saves having to wire a sensor to compensate for thecold junctiontemperature.
GJohn Posts: 112 Rating: (10)
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8/9/2007 6:26 AM	Rate (0)
Arunabha Member Joined: 5/25/2007 Last visit: 9/5/2007 Posts: 6 Rating: (0)	Thanks for your views. I shall use direct termination of compensating cables from thermocouple ton I/O module other than using any third material with more cold junctions. eventhough it will give little difficulties for panel engineering when the nos. of thermocouples are 650. Thanks once more.

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8/9/2007 7:53 AM	Rate (0)
Chook Experienced Member Joined: 6/13/2006 Last visit: 9/21/2023 Posts: 201 Rating: (8)	Hello Arunabha, Can you tell me what your part number and model? , Is it siemens production ? Regards chook
	[IMG]http://i17.tinypic.com/66b7jas.jpg[/IMG]
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8/9/2007 8:57 AM	Rate (0)
SonicRanger Posts: 151 Rating: (8)	Hi Arunabha, To make things easier, take a look at the sitrans TW card: http://pia.khe.siemens.com/index_process_instrumentation.products_solutions.products_systems.temperature_measurement.panel_transmitter-2132.htm Regards, SonicRanger.
SonicRanger Posts: 151 Rating: (8)	Last edited by: SonicRanger at: 09.08.2007 08:59
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