Answer / carl ellis

Although the post has lots of information, it isn't clear
exactly what the problem is.

I think the problem is that the PLC does not alarm when the
pressure exceeds (goes above) 55mbar. But I'm not sure.

Given this description: when PAHH (pressure alarm High High)
goes more than the set point which is 55 it reached up to 71
but due to timer doesn't trip . We force it and we checked
everything nothing there, let's suppose that the PLC is not
indicating an alarm state.

a) what should the PLC do at the alarm condition?
b) How is an alarm indicated? A digital output (DO) goes
high? A lamp is driven by a DO lights up?
c) What exactly does not work as it should?

If the PLC does not indicate an alarm, yet the indicated
pressure goes higher than a high alarm, the problem is NOT
the field transmitter, the problem is in the alarm setup or
alarm annunciation.

Troubleshooting depends on
- an explanation of exactly what should be happening
- an explanation of how you know it is not working; that is,
what the evidence is that it is not working.

Yes, the pressure went above 55mbar.
How do you know that?
The transmitter's local display?
A milliampmeter in the analog input circuit?

Did the alarm ever work? Or is this a new commissioning and
you're trying to get the alarm to work?

Carl Ellis
Measure First

Answer / jigar anadkat

Dear,

As you mentioned pressure shot up to 71 mBar which means channel goes to BAD state and it might not activate the logic. (Truly speaking it should but depends on how the logic has been created and what are the parameters set in IO assignment for failure situation).

If you you are using Yokogawa Prosafe RS the please make sure to take Chanel status as well in the logic configuration. So in case of IOP(+) as well as IOP(-) it will actuate the logic.

Moreover, there is a setting in IO parameter builder regarding input processing at fault situation. Please go through that as well.

Hope this will help you in trouble shooting.

Regards,
Jigar Anadkat
Instrument Engieer
IBN RUSHD
A SABIC affeliate.

i want to control the temp of sand(welding flux) between the range of 150deg C to 170deg C. sugges me sum temp control method without PID controller.

1 Answers  

---

What is the difference between fiber optic cable & Ethernet cable

2 Answers   BEMCO, CCC, Pidilite,

---

How many mode are in ups?

2 Answers  

---

what is cavitation ?

7 Answers  

---

could someone explain for me what is 32-bit Floating Point ? Thanks

1 Answers  

---

why OPC server is used in DCS?

2 Answers  

---

Why boiler chimney area  oxyden sensor fixing? 

0 Answers   NTPC,

---

In instrumentation standard we use 4 to 20ma for transmission , why cant we use 3 to 19ma ?

1 Answers   NSH,

---

What is rang ability?

0 Answers  

---

Why 4-20 amps is being used in instruments? Why cant we use any other range instead of 4-20 amps? Why only 4 amps is taken as lower limit and why 20 amps is taken as the higher limit?

0 Answers  

---

i want to calibrate a transmitter in the range of -100 to 300 mmwc. How it is possible to measure -100 to 300?.

2 Answers   Hindalco,

---

How to calculate 47Liter H2 Gas cyilnder consumtion? Cylinder inlet Pressure is 200bar and Discharge pressure is 6.0bar. Flow is 100ml/min.For the above condition how many days one cylinder can be used?

1 Answers  

---