Dear all... I have 1 0-400 duplex type RTD, I connected the
A side to the temperature indicator and B side to the PLC
panel, but when I have observed then found that The PLC side
temp has the variation. and it was distub to other RTD temp
also. so what can I do.pls help me
Answer / carl_ellis
An offset in readings from separate RTD's can indicate
- a difference in calibration of the analog input devices
- a bad RTD element, one that has drifted out of spec
- a common ground issue with ground loops between the analog
input devices
An RTD is supposed to be ungrounded and the two RTD's in a
duplex element are supposed to be electrically isolated from
one another, so it is unlikely the ground loop is unlikely
unless poor wiring of the extension wire or head wiring has
created a connection to ground.
If you're complaining about a small difference of the
indicated temperatures, then get out your cal gear and cal
the inputs.
To check for a bad RTD, I'd take an ohmmeter and see if any
leg on the A side has any connection to the B side by
disconnecting the wiring from each analog input and check
the resistance. If there's a low resistance, it indicates
some connection from A to B. If the extension wires are
then disconnected and the resistance is checked on the RTD
lead wires and the resistance remains, then it's a bad RTD.
If the resistance goes high (open circuit) then the
extension wire is shorting or making a low resistance
connection somewhere.
Carl Ellis
Measure First
Is This Answer Correct ? | 1 Yes | 2 No |
can we connect instrument earth pit to electrical earth pit, if not why?
HOW CAN I CONNECT ROSEMOUNT 3300 LEVEL TRANSMITTER TO Allen-Bradley SLC500
what are the different types of communication cables used in automation and what are the difference in the cables
why used three wire in RTD.
How a oxygen sensor & analyzer work at boiler or furnace, what’s the principle & science is beyond this, How O2 sensor scene & convert signal & move toward analyzer & analyzer show reading in percent?
1 Answers GS Engineering Construction, KNIC,
What are different types of orifice plates? State their uses.
How is PH sensor works ?
why we are using ungrounded RTD sensor and what is difference between grounded RTD and Ungrounded?
what is the difference between DELTA-V & FOUNDATION FIELD BUS
Isometric drawings are generated during _________________ phase of a project
What is sensitivity of K type thermocouple? Is polarity important in thermocouple connections?
how to check thermocouple ,its working or not?
14 Answers Coca Cola, Ford, Honeywell,