why to use 3 wire at RTD ? what's the reason for common wire ?

why to use 3 wire at RTD ?
what's the reason for
common wire ?

Question Posted / swastikdjain

4 Answers
10772 Views
I also Faced
E-Mail Answers

Answers were Sorted based on User's Feedback

why to use 3 wire at RTD ? what's the reason for common wire ?..

Answer / prince

RTD's work on the principle of RESISTANCE. The two working
wires might have different lengths, so different resistance.
Third wire is used for compensating the extra resistance so as
to get accurate o/p. Third wire is in parallel connection with
one of the wire. In 4 wire RTD, the compensation is more.

Is This Answer Correct ?

13 Yes

0 No

why to use 3 wire at RTD ? what's the reason for common wire ?..

Answer / carl_ellis

It is correct that an RTD indicates a change in temperature
by a change in resistance of an element.

The change in resistance must be monitored electronically
and any circuit connected to an RTD will include copper lead
wires which will add resistance to the circuit.

The problem is not that the lead wires will have different
lengths, the problem is that any copper lead wire has some
resistance which will contribute to a voltage drop from the
source current and appear to be the resistance of the RTD
element. Any contribution of resistance to the measurement
is an error.

Two lead wires connect to the RTD element and a 3rd lead
wire is used to compensate for the added lead wire
resistance so that the lead wire resistance is eliminated
and only the RTD resistance is measured and used to
calculate temperature.

Carl Ellis
Measure First

Is This Answer Correct ?

10 Yes

1 No

why to use 3 wire at RTD ? what's the reason for common wire ?..

Answer / rathod mukesh r

If 2 Wire rtd use , The distance is more between remote location (Rtd) And dcs panle then error occur in reading of temperature. Means if wire length is increases then its own resistance also increase so proper reading is not transmited via 2 Wire. In 3 Wire rtd these error is remove using compensasion lead.

Is This Answer Correct ?

0 Yes

0 No

why to use 3 wire at RTD ? what's the reason for common wire ?..

Answer / yugesh shah

3rd wire is called compensation wire , when RTD is installed
far away from control room or where we get indication then 2
wire RTD fails to send appropriate sign al due to
temperature effect or atmospheric changes so 3rd wire is
helpful to send error free signals or resistance

Is This Answer Correct ?

0 Yes

2 No

Post New Answer

More Instrumentation Interview Questions

why full bore ball valve is not used in steam applications?

1 Answers

model question paper of instrumentation for Jindal GET 2010.plz reply sudhanshukumar08@yahoo.com

0 Answers Jindal,

why we use only 4 to 20ma other than 0 to 16 ma

5 Answers Invensys, Systech,

as an instrumentation engineer which are the things we have to know / or we must have idea about that....

2 Answers

what is the working principle of vortex flowmeter

9 Answers Essar,

What is pressure,What is temperature,What is flow,What is level

4 Answers Keltech, Petrofac,

How to check electrical health of Vibration probe?

1 Answers QAFCO,

The DCS stand for________________________. it is composed of the following major components: a:______________ b:______________ c:______________ d:______________

2 Answers

What is possitive and negative feedback?

3 Answers KNPC,

How can we calibrate the level interface for Fisher® FIELDVUE® DLC3000?if use water to calibrate and our liquid SG are 0.75 and 1 ,Displacer height=14" and How much should be set SG in trasmitter during calibrate,for URV and LRV how shold be set

1 Answers

Why we are using reverse action in displacer types level transmitters on some Vessels?

0 Answers

please someone tell me what is function of vibration sencer and how many types and how to control viberation.please. my id is jimmykhan077@gmail.com

0 Answers

For more Instrumentation Interview Questions Click Here