why to use 3 wire at RTD ?
what's the reason for
common wire ?
Answer Posted / 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 |
Post New Answer View All Answers
In Safe Guarding test what means by "Failed to Danger" ?
I have completed B.E. Instrumentation & control in 2009. i have 3 year industrial job experience in chemical plant.now, I want to join M.E. in external. so, Plese say easiet way and good institute name.
give eg of how I/P is used in control loops
How to decrease opening & closing time of on/off valve?
Area classification, Equipments, Gas groups, temperature classification, Ingress protection, Fire Extinguishers.
Explain the working principle of lvdt?
What are different types of control valves?
how the arrangement of equipments done in control room
why we use cascade control and feed foreword control in 3 element control of boiler drum ?what is feed forward and cascade control system ?
Which type of diaphragm use in costic line, dm water line, natural gas line, oil line?
How to calibration a control valve?
can any one explain in which term we are flow flow is it volumetric r is it mass? and y
How u will setup SPI(2007) on Citrix Server (Thin Client Mode)? Plz Justify?
Define the terms Accuracy, precission, Spam, process tolerance while doing calibration of an instrument? Explaini with an example?
please send data bank of quetions answers on analytical instrumentation.