Interested to Buy Any Domain ? << Click Here >> for more details...
how to connect 3 wire 4-20 mA transmitter in Plc system PLC
system and how explain how the measuring data communicate
with plc system.
- 1 Answers
- 17225 Views
- I also Faced
- E-Mail Answers
Answer Posted / sam
We normally use a clean separate power source to power all
the instrumentation on the plant including the DCS and
PLC's. This instrumentation power source is going through a
UPS and a inverter backup system to smooth and minimize
power failures. Each zone in the plant normally have its own
24VDC power supply unit, but they are all backed up by the
same UPS.
The UPS can normally keep the instrumentation and other
emergency and critical power for about 6 hours in case of a
total main power failure.
In your 3 wire system the supply to your TX will be from
this external power source, and the loop power for your 4 to
20 ma will be generated by the same TX and will not come
from the PLC or DCS as with a loop power 2-wire systems.
Since the external power to your TX is the same as the 24VDC
power it generates for the signal, you can use the negative
as a common. This common(OV) and the 4 to 20mA(24VDC) signal
is then connected to the PLC as for a normal 2-wire loop
powered TX.
This common from your TX is 0V and is the same as the 0V of
the PLC or DCS since they are all from the same UPS.
The PLC or DCS will only get the positive of your TX as the
input signal, since all the negatives of the inputs are all
connected together on a common 0V bar close to the the PLC
or DCS and only one wire from this negatives bar is then
daisy chained to each input. The negative from your TX you
therefore also need to connect to this common negative bar
of the PLC or DCS and only the positive goes to the input
connection.
The only thing you need to remember is that the 3 and 4 wire
systems are externally powered systems and are therefore
active inputs or source inputs and that the loop powered 2
wire system is a passive or sink type input. This you then
need to set up inside the PLC or DCS input configuration
parameters.
Good luck
| Is This Answer Correct ? | 13 Yes | 3 No |
Post New Answer View All Answers
Manipulation of dead wt. tester double piston type.
Speedtronic system .
Gas equation
pls suggest suitable MOC of diaphragm for pressure measurement of UREA grade solution service fluid.
What is difference between “Fault Tolerant” & “Fault avoidance” PLC? Application where these system s are used?
Why upper weighing limit of electronics balance is 90% of the total weighing capacity?
What is intrinsic safety mean.
How does a single acting, spring return ball valve actually work? Does it require continuous air supply?
What is instrumentation control?
What is the diffrence between ff tx and non ff tx
What are different types of cable?
i am from instrument branch i want paper patern of mahagenco . any pevious years paper regarding my branch send me please . please.....
Q- What are the application in which PNP transistor is preferred over NPN ?
why we are not using the turbine flow meter in the steam service?
the 3 most common transmitter protocol being in refinery or qatar gas and aramco.
