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can a PT100 with transmitter be broken because my pt100 measures temperatures that are a bit to high?

Created by: fvanluchene at: 3/1/2011 6:22 PM (10 Replies)

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3/1/2011 6:22 PM	Rate (0)
fvanluchene Posts: 19 Rating: (0)	I got 2 questions first a stupid one can a PT100 with transmitter be broken because my pt100 measures temperatures that are a bit to high I think so how can i clear my problem. maby it's because I wire my PT100 4MDU but I use only 1 channel so maby i must connect CH1 with Mana or do I need to do something else with my CH1? [schnippschnapp] second question is splitted to what is the best way to dim a lamp that works on 230V AC with my PT100 what goes from 0-10V DC.
fvanluchene Posts: 19 Rating: (0)	Last edited by: O_Moderator at: 3/2/2011 10:32 AM
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3/2/2011 3:56 PM	Rate (0)
fvanluchene Posts: 19 Rating: (0)	sorry for the double post but i realy need to find my fault. My PT100 with transmitters says its 30° and my weather station says its only 22° so my PT100 measure 8° to much. so what could be the fault? -could my PT100 has been damaged -only wired 1 CH (CH0) and done nothing with CH1 -something else
fvanluchene Posts: 19 Rating: (0)
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3/2/2011 7:37 PM	Rate (0)
danw Gold Expert Joined: 3/28/2010 Last visit: 12/24/2024 Posts: 1099 Rating: (216)	Transmitters or analog inputs connected in "two wire RTD" mode can exhibit temperature error due to lead wire resistance. Read the resistance of the RTD disconnected from anything else) and compare it to the value from a chart of temperature vs resistance for PT100. How good is the correlation?

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3/2/2011 8:17 PM	Rate (0)
fvanluchene Posts: 19 Rating: (0)	I disconected my Transmitter and measured the temperature of my PT100 and the result was 105ohm in a room of +-15° (i'm now measering the temperature in the room with a weatherstation) so if i look to the information of a PT100-3L i see that: 10°C= 103,85055ohm 20°C= 107,7011ohm --> conclusion the PT100 is good. So what i do next? to find the result
fvanluchene Posts: 19 Rating: (0)
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3/3/2011 2:31 PM	Rate (0)
danw Gold Expert Joined: 3/28/2010 Last visit: 12/24/2024 Posts: 1099 Rating: (216)	What color wires and how many of each on the PT100? What brand and model device are you connecting the PT100 to ? Please provide a link to that device's manual:

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3/3/2011 5:10 PM	Rate (0)
fvanluchene Posts: 19 Rating: (0)	1red wire and two black ones. the type is PT100-3L number is WT7031-1240 and i'm connecting it on 331(6ES7331-7KB02-0AB0) http://support.automation.siemens.com/WW/view/en/8859629
fvanluchene Posts: 19 Rating: (0)
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3/4/2011 8:07 PM	Rate (0)
danw Gold Expert Joined: 3/28/2010 Last visit: 12/24/2024 Posts: 1099 Rating: (216)	The spec sheet for the WT7031-1240 is here: http://www.tematec.de/data/WT7031GB.pdf Do you have a temperature transmitter (field 14 in the part number) as part of that assembly? If so, which one? Or are you connecting the three wires from the RTD sensor directly to the 7KB01 analog input module?

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3/4/2011 9:40 PM	Rate (0)
fvanluchene Posts: 19 Rating: (0)	yes i have one (the transmitter gives the signal to my SM331) and i suposse its the analog one i'm sure it's not a digital one (2,3,4) and i'm sure it's not one with hart protocol (7) . I think (99% sure) that its number 1 analog one non isolated because it are just conductive pins where i put my wires on and then put a screw on it with a screwdriver and sorry you have right that is the right pdf. my pt100 is connected like 1xPT100-3 wire circuit (you can see in pdf)
fvanluchene Posts: 19 Rating: (0)	Last edited by: fvanluchene at: 3/4/2011 9:54 PM
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3/5/2011 1:56 PM	Rate (0)
danw Gold Expert Joined: 3/28/2010 Last visit: 12/24/2024 Posts: 1099 Rating: (216)	The first thing to pursue is, is the wiring correct? To get there, it's very important to understand exactly what components are being used. I still don't. If there's a transmitter involved, then what brand and model is the transmitter and what is its wiring configuration? The drawing labeled "1xPT100-3 wire circuit" in the RTD spec sheet shows wiring connnections for the RTD sensor wired to the internal connection block inside the die cast screw cover head. That spec sheet shows no wiring for a transmitter; those wiring diagrams are for RTD sensors only. If you have a transmitter that converts the RTD into a current signal, then how is the RTD wired to the transmitter ? What brand and model is it? What is its output range or what does the 4-20mA output represent? 4mA = ____°C 20mA = ______ °C

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3/5/2011 5:42 PM	Rate (0)
fvanluchene Posts: 19 Rating: (0)	there is no information of the transmitter given in the book but there is one because i connect the transmitter to L+ and pin 2 of my SM331( 4MDU connection) there stands only in my compact instructions that it's a head transmitter. The transmitter is of the analog kind. 0°=4mA 100°=20mA
fvanluchene Posts: 19 Rating: (0)
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