Rtd

[krome]

i want to add a RTD which i still havent bought i want to add it to a PLC what do i need to do before i get a signal out of it. if i understand correct i cant connect it directly to the I/O seeing that they dont give out an 0-10V or 4-20ma output

 

[George Graziano]

I would get a rtd transmitter if you have an open analog in. Most are 4-20mA, you could convert to voltage with a precision resistor. Unless you have enough rtd's to almost fill an rtd input card, I don't think it would be worth it to go that route.

George

 

[Roy Matson]

No you need a transmitter. The RTD vendor will probably be able to sell you one pre-calibrated, something like a hockey puck or rack mount.
It's generally easier to put the transmitter in the field so you don't have to run 3 wire cable.
Pt 100 is the most common type of RTD but if you give us some more details will be able to help further.


Things to think about
Do you need a display at the RTD
What is the measuring range
Do you have 24 VDC available
Do you have other RTDs on site, how are they done.

 

[krome]

it doesnt need to be display it going into the PLC for trending purpose. 0 120 C would be fine or 0 to 300 F i can have 24vdc available would try to avoid it but it can be done. no other RTD that i know of. do you have any website that could be helpful for purchasing them thanks i truly appreciated it.

oh the RTD are for bearing of a generetor

 

[BTalbot]

This new signal conditioner from Red Lion will do the conversion. You can probably find a less expensive unit, this unit has a lot of features. A place like Omega may have cheaper signal conditioners.

http://www.redlion.net/Products/Groups/ProcessInputs/IAMS/Docs/10024.pdf


Disclaimer:
I work for a Red Lion distributor on the east coast. I am not trying to make a sale just trying to help.

 

[krome]

i was looking at the omega one im just comfused with it set up does any rtd work with it and do you need to add the resistor to it output and how would you conecct it to a plc?

sorrry i know this are dumb question but i want to make sure i understand the set up

 

[krome]

on the omega manual it state it accept platinum 100W sensor type, is the W for ohms???

 

[Mickey]

Can you post a link to the manual or the Model number of this Omega Transmitter.

 

[Boxy]

Look at what the PLC Analog In cards can take. I know that there are some Siemens AI cards that can take an RTD without a transmitter in between. All that is needed is it to be configured to RTD in the Hardware Config.
Do you mind me asking what type of PLC?

 

[krome]

http://www.omega.com/Manuals/manualpdf/M3754A.pdf here the manual that say the W

http://www.omega.com/Manuals/manualpdf/M1253.pdf here the manual that say ohms

it a GE PLC

 

[Mickey]

Both links are for 100 ohm Platinum RTD input with a 4-20ma output transmitter.
See link below for a reasonable answer for what "W" means. Its as good an answer as any.

http://www.control.com/thread/1236680564

 

[jayc12155]

Points to be considered while selecting RTD.
1.Temperature range
2.Process connection and length of the RTD
3. accuracy say Class A,B or C (2,3,or wire)RTD/PT100.
4.Does your PLC supports Pt100 input, say for example Siemens PLC has one Pt100 input module or some S7200 has built in.
5.Distance between Pt100 and Control panel or to the input module.
6. If distance is more use 4 wire RTD or If you wish to use 4-20 ma/ 0-10V go for a temperature transmitter.
There are DIN rail mount temperature transmitter and also Head Mount Temperature transmitter.(You have 4-20ma/0-10V with ot without HART)
I would suggest for in for STATUS Instruments make as they are economical and come with 10year warranty for Temperature transmitter.

 

[Roy Matson]

Krome,
Both the Omega models you attached look OK but the 2nd is the better of the two. I assume your generator is not a multi M$ investment or it would already have bearing monitors.
The advantage of the Omega over a modern HART unit, you can calibrate it without any fancy equipment. Take you RTD and stick it in an ice bath, thats 0 C, boiling water that's 100 C or close enough for a generator bearing. Of course if you have a decade box it's quicker.
Wire the RTD up with 3 wires as they show in the diagram.
The TX92-2 should suit your purpose, the manual says the Zero and Span can be adjusted by 25% otherwise range 3, just pick one thats a few % higher than your trip value

Good Luck
Roy

 

[longshanks]

You might also try Wilkerson Controls or Action Instruments. Both have powered transmitters, which would supply the 24vdc 4/20ma loops so a seperate power source wouldn't be required.

 

[wallypiper]

Powered transmitters have to have a source of power. They don't make power. They are just 3 wire or 4 wire transmitters as opposed to "loop powered". So you still have to have a "separate" source of power somewhere.