Restriction of RTD wire lenght

[Forrest]

Is there any restriction to the lenght of RTD?

If the RTD is 10m apart from my controller, should I need to order a RTD with 10m long of wire and conect it to RTD module directly?

Or, I only use a RTD with 1m long wire and connect the wire end to terminal and then connect my RTD module with that terminal?

Thanks

 

[kingofdarkness4]

what type of RTD? 2 wire, 3 wire, 4 wire?

EDIT:

Also, What is the application?

I have put RTD's in an underfloor temp monitoring system. Transmitter was in a JBOX about 100 Feet away. Transmitter was a 4-20ma.

As far as I know, with 2 wire its better for it to be shorter, but with 3 wire you can go farther with it since it uses 2 wire to measure the ohms of the wire all the way there and back and the transmitter adjusts its equation.

 

[sthompson]

Is there any restriction to the lenght of RTD?

If the RTD is 10m apart from my controller, should I need to order a RTD with 10m long of wire and conect it to RTD module directly?

Or, I only use a RTD with 1m long wire and connect the wire end to terminal and then connect my RTD module with that terminal?

Thanks

2 Wire I wouldn't go very far, it should be close. 3 Wire and 4 Wire you can go a good deal farther. We have 3 Wire RTDs that are in the hundred meters plus range. 10 meters should be no problem for a 3 Wire or 4 Wire RTD. If you Google it, or look at Omega Instruments, you might find a more definitive answer on the maximum length.

Stu.....

 

[TConnolly]

If you do have a two wire RTD with short leads then you can still wire it to a three wire instrument by attaching two wires to one of the RTD leads and 1 wire to the other. The RTD controller will still use the third wire to measure lead resistance and cancel it out. In this case keep the actual RTD leads as short as possible while the extension wire can be several meters in long with no problems.

---------------------------+    +---+

                           |    |   |

---------------------------+----+   |

                                |   |

--------------------------------+   |

                                |   |

                                +---+  

                              2-wire RTD

 

[Forrest]

Thanks for your information!!

We are using 3 wire RTD and the RTD is placed inside a water tank.

I will put a junction box beside the tank and than connect the controller to the junction box directly. It seems that resistance of the wire can be cancelled out if 3 wire RTD is used.