0:00
Hello everyone myself Baradwas. If you
0:03
see here this is the wall positioner.
0:06
This is the brain of the instrument. It
0:08
will control the required wall stem
0:12
position. So this is the wall stem. This
0:15
is connected to wall positioner using
0:18
this mechanical linkage. Whenever the
0:22
wall stem operates that means either it
0:25
can move downwards or upwards. You can
0:28
see the scale here. Right now it is in
0:31
closed position. Every control wall
0:34
requires one analog output signal from
0:37
the DCS system to the wall positioner.
0:40
This is the command signal. For that we
0:43
need one pair cable. You can see here
0:46
there are two cables. One is for command
0:50
signal or control signal. The second one
0:54
is feedback signal. We can take 4 to 20
0:58
milliamp signal as a feedback so that we
1:01
can show the exact wall status how much
1:06
it is opened or how much it is closed
1:09
like let's say 50% open 60% open 70%
1:14
open 75% is open like that we can give
1:18
the feedback to the operator display
1:21
using feedback signal for that purpose
1:25
we need one more one pair cable. See
1:30
mostly in industries we have 4 to 20
1:33
millia based signals. Every control hall
1:38
command signal and one feedback signal
1:41
type of signal, one AI and one AO
1:46
signals are required. You can see on
1:49
this control wall we have hand wheel
1:51
also available so that the operator can
1:55
move the wall stem position using this
1:58
hand wheel during startups or during
2:01
emergency situations. Now we can see
2:04
here I am operating the control valve.
2:07
You can see the position here it is
2:09
moving. See volume stem is moving the
2:12
display. You can see here on the scale 0
2:16
You can see the scale also how much it
2:18
is open or how much it is closed.
2:22
This is how the wallve operates.
2:25
Right now I'm giving some signal from
2:27
the DCS system and the DCS system is
2:30
giving the equivalent 4 to 20 millia
2:33
signal to the wall positioner and then
2:36
WO positioner sends the equivalent
2:39
instrument air supply to the actuator.
2:42
Then as per the received instrument air
2:45
supply the actuator operates this wall
