how use RTD MODULE,SIEMENS

[raha_fi]

Hi
i use em 231 rtd madule for my project.we have 3 pt-100 that these are serial with each other( 300 ohm),but we have only two end connection of these.how i can configure these rtd to EM 231 OF S7-200 SERIES madule thanks alot

 

[JesperMP]

we have 3 pt-100 that these are serial with each other( 300 ohm)

This does not compute. 3 Pt100 in series ? Maybe you have 3 thermistors in series for motor winding protection. If this is the case, then it is not according to Pt100 standard but to "thermistor" standard.
Some motors have 3 Pt100 sensors in the windings for motor protection, but then you need 1 Pt100 relay or analog input module per sensor.

 

[raha_fi]

Hi
with thanks
We have one pump ,that vendors used 3-RTD(PT-100)in it's stator,but as I said we have only first and end of these RTDS so we can not connecte each of these to separate madule.
do you know solution for this?
0---/\/\/\---/\/\/\---/\/\/\---0
We have only two connection of above pictures(0)

 

[JesperMP]

Hi raha_fi.

Are you absolutely sure that the sensors are Pt100 and not thermistors ?
Thermistors are quite common in motors whereas Pt100 are more esoteric.

The Pt100 standard says that at 100 ohms the temperature is 0 degr.C.
So connecting the Pt100 sensors in series is definitely not to the Pt100 standard.

Go to the vendor and ask him for an example on how to connect it.

 

[raha_fi]

Hi
Yes,I'm sure.
Another question.Is it possible to seri one 200 ohms resistance to this configuration in the junction box and then suppose these as RTD-500 .
So configure EM 231 FOR PT-500
Thanks alot for your help.

Raha

 

[JesperMP]

Is it possible to seri one 200 ohms resistance to this configuration in the junction box and then suppose these as RTD-500.

No, the characteristic curve of the 3 times Pt100 + 200 ohm resistor will not be the same as a Pt500.

Ask the vendor how to connect the sensors.
And tell us the result.

 

[Amr Hassan]

Dear Raha

this is from the data sheet of the module u are using
i think if u use type R 600 , it may work
u should find the way how to scale this reading
u must do a try an error for that


good luck

RTD types:

· Pt 100 W, 200 W, 500 W, 1000 W (a = 3850 ppm, 3920 ppm, 3850,55 ppm, 3916 ppm, 3902 ppm)

· Pt 10000 W(a = 3850 ppm)

· Cu 9.035 W(a = 4270 ppm)

· Ni 10 W, 120 W, 1000 W (a = 6720 ppm, 6178 ppm)

· R 150 W, 300 W, 600 W FS

 

[JesperMP]

Amr Hassan

If raha_fi uses the R600 mode, he will get a resistance value and not a temperature value. I dont think it will be useful to him.

 

[Amr Hassan]

he can scale it after that

for example if he is reading 360 ohms this means on the average 120 ohm which means about 50 degree i guess

note that this is probably for monitoring accuracy is not needed very much

 

[JesperMP]

The Pt100 and Pt500 standards do not have a linear relationship between temperature and resistance.
Scaling is possible but not so easy.

I really think that the vendor has to explain how to connect the sensors. It is the only way to avoid misunderstandings.