About kishore karuppaswamy

Iam Btech having experience in saudi aramco as instrument engineer

How to line up interface Level Transmitter

Consider an interface level transmitter as shown below

 

interface lt

 

This section covers how to line up an interface level transmitter .One of the most frequent problem encountered in a plant is that the level transmitters which is installed in the tank or vessel for PCS and ESD level is not matching. There are many reasons to this like parameters mismatching, choking due to slug, heat tracing not working resulting in leading to choking, ripples in the vessel due to suction and filling of vessels using high pressure pumps, different tapping points for ESD and PCS level transmitters, (technology)types of the transmitters used , their response time, sensing element response time failure due to prolonged use, foam in the interface, sudden temperature changes, trapped pressure in the level transmitter chamber, improper line up of transmitters and many more oceans of reasons……….

But line up of transmitter plays a vital role in the reading matching of both ESD and PCS LT

The line connected to the bottom of the tank may be called as HP tapping point because high pressure is experienced compared to other points due to gravity, the middle tapping point can be called as Medium pressure MP point or interface point and the upper tapping point where generally air or gas is present can be called as LP or low pressure point.

To the point, I will describe a method to line up of interface LT

  • Assume that the interface LT is isolated from the process line

  • Initially line up the gas point or LP tapping point

  • Then line up the interface tapping point or MP point and wait for the 3 or 4 minute to settle

  • Finally after 5 minutes line up the HP tapping point

  • Allow the process to settle

  • Wait for more than one hour to settle and to get a stable reading

  • Follow the same procedure for both ESD and PCS LT

 YOUR IDEAS AND SUGGESTIONS ARE ALWAYS WELCOME REGARDING THIS TOPIC

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pH analyzer working principle and Calibration

pH is the measurement of acidity or alkalinity of an aqueous solution and its hydrogen ion concentration. The pH scale is a logarithmic scale and ranges from 0 to 14.Neutral solutions, and pure distilled water, which have neither acidic nor alkaline content, have a pH value of 7, acids have values below 7 and alkalis have values above 7

In aqueous solutions, a compound dissociates into charged particles called ions. Any strong acids, when dissolved in water will produce positively charged hydrogen ions and negatively charged acid radical particle ions as shown below

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As all strong acids are fully ionized in aqueous solutions, a measure of hydrogen ion concentration will give the strength of acid

One of the many methods used to fine the pH value is electrometric method which can be explained as below

This method is used to continuously monitor the degree of acidity or alkalinity of the process liquid. Basically an electrode immersed in a liquid acquires an electric potential, the value of this potential varies with the value of the pH of the liquid. As it is impractical to measure a single potential, we use two electrodes and a potential difference is measured. The different types of electrodes used are glass measuring electrode, calomel reference electrode and submersible electrode assemblies.

In a glass measuring electrodes which is most widely used one,2

This comprises of a bulb made of special glass which is fused into the end of a glass tube to form a membrane. This membrane is sensitive to hydrogen ions. This assembly contains a solution of HCl of known pH value and a silver wire coated with silver chloride is dipped into HCl. This silver wire is connected to a screened lead and the glass tube is sealed in the top cap

When the electrode is placed in a solution, a potential difference is established across the membrane. The value of this potential depends on the pH of the solution This potential difference from the pH sensor is then converted to mA in the transmitter and transmitted to the control room.

Calibration Procedure of pH analyser

1.Obtain necessary Permit to Work. 2.Override the trip if it is connected to any trip system.

3.Isolate the sensor from process & remove the sensor. Place it into the insulated container of water along with a calibrated thermometer.

4.Be sure the glass bulb and the reference junction are completely submerged. Stir continuously.

5.Allow the sensor to reach thermal equilibrium.

6.Press “MENU” key on the transmitter, then menu screen appears.

7.Chose “Calibrate”.

8.Chose “Temp”.

9.To calibrate the temperature, change the number in the second line to match the temperature measured with the “Standard Thermometer”.

10.Press “ENTER”.

11.Press “MENU” then “EXIT” to return to the main display.

12.For pH AUTO calibration go to the

     step13 & for MANUAL calibration go to       the step 35.

Auto Calibration

13.Obtain two buffer solutions of 7.00 & 10.1 pH.

14.Press “MENU” key.  The main menu appears. 

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15.Choose “Calibrate”.

2

16.Choose “Sensor 1” and then “pH”.

3

4

17.Choose “Buffer Cal”.

5

18.Choose “Auto” and then enter “Start Auto calibration”

6

7

19.Choose “Buffer1”.

20.Rinse the sensor with water and place it in buffer 1.  Ensure that the glass bulb and the reference junction are completely submerged.  Swirl the sensor

8

21.The screen on transmitter is displayed with “Wait” flashing until the reading is stable. The default stability setting is <0.02 pH change in 10 sec.

22.Display shows the actual reading.  The transmitter also identifies the buffer and displays the nominal buffer value9

23.If the display value is not correct Press “UP ARROW KEY “or “DOWN ARROW KEY “to alter it to the correct value.

24.Press “Enter” to store.

25.“Cal in progress” screen will appear momentarily.

26.Remove the sensor from Buffer 1, rinse it with water and place it in Buffer 2. . Be sure the glass bulb and the reference junction are completely submerged.  Swirl the sensor.

27.Choose “Buffer2”.

28.The screen on transmitter is displayed with “Wait” flashing until the reading is stable.

9a

29.Display shows the actual reading. The transmitter also identifies the buffer and displays the nominal buffer value.

9c

30.If the display value is not correct Press “UP ARROW KEY “or “DOWN ARROW KEY “to alter it to the correct value.

31.Press “Enter” to store.

32.“Cal in progress” screen will appear momentarily.

33.If the calibration was successful, the transmitter will display the offset and slope

9d

34.To return to the main display, press “MENU” then “EXIT”.

9e

9f

 

                        MANUAL CALIBRATION

35.To perform the MANUAL calibration follows the steps from 36.

36.Press “MENU” key. The main menu appears. 

37.Choose “Calibrate”.

38.Choose “pH”.

39.Choose “BufferCal”.

40.Choose “Manual”.

41.Choose “Buffer1”.

42.Rinse the sensor with water and place ii in buffer 1. Be sure the glass bulb and the reference junction are completely submerged.  Swirl the sensor.

43.The reading in the top line is the live pH reading. Wait till the reading is stable.  Then, use the arrow keys to change the reading in the second line to the match the pH value of the buffer.

44.Remove the sensor from buffer 1 and rinse it with water. Place it in buffer 2.  Be sure the glass bulb and the reference junction are completely submerged. Swirl the sensor.

45.Choose “Buffer2”.

46.The reading in the top line is the live pH reading. Wait till the reading is stable.  Then, use the arrow keys to change the reading in the second line to the match the pH value of the buffer.

47.“Cal in progress” screen will appear momentarily.

48.If the calibration was successful, the transmitter will display the offset and slope.

49.To return to the main display, press “MENU” then “EXIT”.

50.Rinse the sensor with clean water.

51.Restore the sensor in process.

52.Observe the reading in HMI and ensure that the reading is as per the process. Inform production department and normalize the override is applicable.

53.Close the Work Permit.

India

Mmmuuuah………My kisses to my motherland……today we celebrate our 71st Independence day….why India is so special?????

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  • India is the biggest democracy in the worldUntitled

  • The most populated country in the world(I don’t believe in Indian census, India is more populated than China)

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  • The most ancient civilization in the world, the cradle of civilization

  • The birth place of 4 important religion namely Hinduism, Buddhism, Jainism, Sikhism

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  • India is among the top five producers of milk,tea,spices,sugar,

    cotton,rubber,coffe,fish,

    jute,banana,millet,rice,

    wheat,sorghum,lettuce,

    drybean,onion,cabbage,

    chickpea,pulses,cauliflower,

    egg plant, potato, spinach,

    soya bean,tomato,ginger,pumkin,

    squash,gourd,rapeseed,safflower

    ,sesame,okra,mango,coconut,

    sugarcane,orange,papaya,

    apple,lemon,guava,jackfruit,

    pomegranate,goat,cashewnut,

    peanut,egg,tobacco,silk,

    wood fuel …………..

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  • India is among the top 5 producers of minerals like thorium, mica, coal, aluminium, bauxite, iron ,manganese, zinc

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  • The largest consumer of gold

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  • India discovered zero and number system

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  • Plastic surgery originated in India

  • The biggest film industry in the world

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  • The most wide spread railway network in the world

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  • India has the lowest consumption of non-veg in the world

  • Lowest crime rate by percentage of population

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  • One of the best secret services in the world (R&AW)

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  • More than 200 rivers

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  • The most intellectual persons of the world

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  • The fastest growing economy in the world

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  • India is among the top five forces in Army, Navy, Air force, Rocket science, Nuclear technology and submarines

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  • Snake and ladders, chess, kabbadi, hockey, playing cards, polo, judo, karate, ludo, caroms all originated in India

  • Most English speaking country behind America

  • India discovered water on moon

  • The highest cricket ground in the world

  • The largest postal network in the world

  • Cherapunji the largest rainfall receiving place in the world

  • The first country to mine diamonds

  • The c pilgrimage in the Thirupathy Balaji temple is the largest people gathering

  • One of the three countries that make super computers

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  • The birth place of yoga

  • Indians discovered pi, trigonometry, geometry, algebra, calculus, cataract surgery, buttons, shampoo

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  • Microwave communication was invented by J.C.Bose of India

  • The first medicinal science ayurveda and siddha is from India

  • Gravity was first explained by Aryabhatta

  • God particle boson was discovered by Sathyendranath Bose

  • Stellar structure and stellar evolution was discovered by Indian Chandrasekhar

  • Indian CV Raman discovered Raman effect

  • Indian Panini was the first to introduce grammar to languages

  • Mathematical genius Ramanujam is from India

  • One quarter of the work force in the world is from India

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  • The first university in the world was in Takshasila India

  • India has 1652 dialects and languages

  • The Pentium chip and hot mails are invented by Indians

  • All of India is on one time zone

  • India has the most number of seasons than any other country

  • India is the largest exporters of software

  • India has the world record of launching 104 satellites using a single rocket

  • The world’s biggest family of Ziona chana is in India

  • 70 % of all spices come from India

  • Indian housewives hold 11% of world’s gold

  • Only one in 100 marriages end in divorce, one of the lowest rates in the world

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  • India has the more people using internet

  • India has the most public holidays in the world

  • India have a very best pool of scientists and engineers in the world

  • India is the first country to sent space craft to mars in first attempt

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  • India has one of the largest road networks in the world

  • The highest battle field in the world is Ladakh in India

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  • India is the outsourcing capital of the world

  • Navigation was invented in India

  • It is the only nation to develop thorium based nuclear plant

  • India has the most cost effective satellite launch capability

  • India has the world’s cheapest car nano

  • India has the cheapest call rates in the world

  • World’s largest producer of two wheelers

  • Have the largest oil refinery in the world

  • Have largest number of bank account holders

  • India have more dance forms than any other country

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  • My fingers are aching………………..

Let me conclude

“India is the cradle of human race also the birthplace of human speech. The mother of history, the grandmother of legend also the great grandmother of tradition. Our most valuable and most constructive materials in the history of man are treasured up in India only.”–These were the beautiful lines given by Mark Twain.

“If I were asked under what sky the human mind has most fully developed some of its choicest gifts, has most deeply pondered on the greatest problems of life, and has found solutions, I should point to India.”Max Mueller

…………WELCOME TO INDIA

OIL IN WATER ANALYZER

The measuring principle is based on fluorescence: when lighted at a specific wavelength (excitation), some chemicals re-emit light (emission) at another longer wavelength according to Beer Lambert law. 

Very few chemicals are fluorescent and give a highly selective measurement. The emission light is detected by a high sensitivity photo multiplier to detect very low concentrations from a few ppb(particles per billion). The excitation light is controlled by a detector to compensate any variation of the source.The most generally used OIW analyzers are Forbes Marshal and AWA 

BS&W Analyzer

Principal of operation ‘Oscillator Load Pull’  analyzers (BS&W) achieve superior performance by utilizing microwave oscillator load pull. Load pull is the term given to describe the frequency change of an unbuffered oscillator as its output load varies. Circuit components and the external load impedance determine an unbuffered oscillator’s frequency. The permittivity of the materials in the measurement section, through which the microwaves propagate, determine the output load. The measurement section consists of a small solid rod mounted inside a larger diameter pipe, as shown in Figure 1. One end of the rod is connected to an unbuffered oscillator and the other end connects to the center of a welded “shorting” plug. The center rod is covered by a hard plastic sheath to prevent direct contact between the metal rod and conductive water-oil emulsions. Electrically this pipe, rod, and sheath combination is a coaxial transmission line, terminating into a short circuit. The fluids flow through the measurement section via the connections that mount perpendicular to the run section, one at each end. The microwave signal travels the length of the pipe twice; down the pipe from the oscillator, then reflects at the shorting plug and traverses back to the oscillator module

The permittivity of the emulsion changes as the percentage of water in the total fluid changes. The permittivity of the emulsion is comprised of two parts – the dielectric constant and the loss. The relative dielectric constant of oil is 2.2 and of water is about 70. The loss is determined primarily by the salt content of the water. Accurate measurement of the water salinity and proper input to the electronics unit is essential for best accuracy of the Phase Dynamics Full Range WaterHydrocarbon Analyzer. In summary, the permittivity of the oil-water emulsion in the measurement section provides a complex impedance, or load. The load acts directly upon the unbuffered oscillator to force a predictable, repeatable, and precise change in frequency. This frequency is proportional to the water content of the emulsion. Temperature and loss also affect the frequency; both are used for compensation to calculate the correct water content. The microprocessor uses the measured frequency to calculate and update the water content each second.The best make of BSW analyzer is from phase dynamics

 

“In OLP,oscillators frequency changes when its load impedance changes.Here the oscillator operates in microwave frequency and is propageted through the measurement section which is the load and the measurement section is dipped in liquids of permittivities or the dielectric constant of the emulsion.Thus as the impedance changes due to a change in percentage of water in oil,the frequency changes.The frequency and the fluid temperature are measured and gives a value in water content”

Capacitance type Level Transmitter

The principle of capacitive level measurement is based on the capacitance change of a capacitor. The probe and the tank wall form a capacitor whose capacitance is dependent on the amount of product in the tank: An empty tank has a lower, a filled tank a higher capacitance

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The working principle is based on the based on the change of capacitance. The insulated electrode of the electrode acts as the one plate of the capacitor and the tank wall (or the reference electrode in a non metallic vessel) acts as the other plate. The capacitance depends on the fluid level. From the equation below

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it is clear that as the dielectric constant varies as the level increases, capacitance increases and this change in capacitance is directly proportional to level of the liquid

Calibration of transmitter

Isolate the level transmitter from the field .Bleed off the trapped pressure and check whether transmitter shows zero reading.

Connect HART to the level transmitter. Clean the probe if contact type transmitter is used. Fill the corresponding liquid in correct density and note down the readings. Fill liquid at 25%, 50%,75% and 100% in both ascending and descending orders and note down the readings. See if there is any error in readings. If there is considerable error do zero and span calibration.

For zero calibration fill liquid up to 10mm or fully drain the liquid and wait for stabilization and then go to sensor trim in HART and then go to zero trim and do zero trimming. In case of non smart capacitance type LT connect a multimeter in series and rotate the zero screw (pot) until the multimeter shows 4 mA or press the zero button until multimeter shows 4mA

 

For span calibration, fill 100% of range in the chamber and wait for stability, then go to sensor trim in HART and then go to span trim and after steady reading is achieved do span trim. In case of non smart devices, fill the chamber till the maximum level where we require 20mA and then rotate the span screw (pot) to set 20mA in multimeter or press span button until the 20mA reading is achieved.

After doing zero and span trimming again check the reading at 0%, 25%, 50 %,75 %and 100%. If everything is OK we can take the transmitter in line

LRV and URV of Interface Level Transmitter

 

I WILL DESCRIBE A SIMPLE PROCEDURE TO DETERMINE THE LRV AND URV OF INTERFACE TYPE LT CAPILLARY TYPE

LET US CONSIDER THE INTERFACE AS BELOWLT

FOR INSTANCE THE TAP TO TAP MEASUREMENT OF CAPILLARY FLANGES BE 3400mm WC (LEVEL TO BE MEASURED), THE HIGHER SPECIFIC GRAVITY LIQUID BE WATER OF SPECIFIC GRAVITY 1.05 (YOU CANNOT EXPECT 1.00 BEACAUSE IT IS NOT MINERAL WATER INSIDE TANK) AND LOWER SPECIFIC GRAVITY LIQUID BE CRUDE OIL OF 0.876,THEN INTERFACE MEASUREMENT CAN BE DONE USING A SIMPLE WAY AS EXPLAINED BELOW,

  1. INSTALL THE LT AND POWER UP THE TRANSMITTER,ISOLATE THE PROCESS AND VENT TO ATMOSPHERE AND DRAIN THE PROCESS, THE TRANSMITTER WILL SHOW A VALUE LIKE -3042mmWC (EXAMPLE) DUE TO PRESSURE OF SILICONE OR GLYCOL FILLED INSIDE CAPILLARY OF HP AND LP,NOTE THIS VALUE

  2. FOR LRV(0% INTERFACE LEVEL  4 mA) CONSIDER THE TANK OF HEIGHT 3400 FULLY FILLED WITH CRUDE OIL OF SPECIFIC GRAVITY 0.876,THAT IS THERE IS NO WATER IN TANK THEN LRV CAN BE FOUND AS LRV=3400*0.876 PLUS -3042 WHICH WE GOT DURING STEP 1 , THAT IS     LRV=(3400*0.876)+ (-3042 ) =2978.4-3042=  -63.6 mmWC

  3. FOR URV(100% INTERFACE LEVEL 20mA),CONSIDER THE TANK FULLY FILLED WITH WATER OF SPECIFIC GRAVITY 1.05,THAT IS THERE IS NO CRUDE IN THE TANK OF HEIGHT 3400 URV CSN BE FOUND AS FOLLOWS URV=3400*1.05 PLUS (-3042)                 =3400*1.05+(-3042)

    =3570-3042=528mmWC

  4. THUS LRV= -63.6 mm WC

  5. URV= 528 mm WC

NOTE THAT THIS IS FOR INTERFACE LEVEL MEASUREMENT DONT CONFUSE THIS WITH DIRECT LEVEL MEASUREMENT         

For more information on interface lvel transmitter click on the link below

https://kishorekaruppaswamy.wordpress.com/2017/01/02/lrv-and-urv-determination-for-d-p-type-level-transmitter/

Instrument Loop Diagrams

Loop diagram represents detailed drawing showing a connection from one point to control system. It could be connection between:

  • Field instrument to control system (or vice versa)

  • Signal from Control Panel to control system (or vice versa)

  • Signal from MCC to control system (or vice versa)

  • Signal form one control system to another system

 

Classification of Loop diagram

Simple classification can be done as

 

PCS/DCS loop diagram for controlling and indication

 

ESD loop diagram for emergency shutting down of instruments

 

F& G loop diagram for fire and gas related alarms/operations

 

This can be further classified into subcategories as AI/AO/DI/DO loops

 

N.B. all signals (voltage or current) is considered with respect to control room. Thus if a signal is going out of control room for closing opening control valve and on/off valve it is considered as an output signal, examples are analog and digital outputs AO/DO and if signals come into control room giving the indication, position, level, temperature, pressure etc it is considered as input signals examples are AI and DI signals.

Analog signals have many values which changes with respect to time like 4 to 20mA for measuring pressure temperature level etc, while digital signal will have only binary values like 0 (off) and 1(on) conditions of on/off valve, status of on/off valve, closed open condition of switches, motor on/off condition etc.

 

Let us consider the 3 loops individually

 

PCS/DCS loop

 

This can be further classified as

 

PCS AI

PCS DI

PCS AO

PCS DO

 

ESD loop

This can be further classified as

ESD DO

ESD DI

ESD AI

ESD AO (generally not used because in case of emergency we need immediate action which can be achieved through ESD DO signal)

 

F&G Loop

 

FGS DO

FGS DI

FGS AI

FGS AO (generally not used because in case of emergency we need immediate action which can be achieved through FGS DO signal)

 

Loop diagram shows instrument (in a symbol) and its terminal numbers which are to be connected, instrument cable number, junction box number, terminal number assigned for the specified instrument, multi-pair cable and  pair number , marshalling cabinet number, terminal number in marshalling cabinet, control system details (rack, slot, I/O channel). It also clearly indicates location of each equipment by means of border line as a limit.
Loop Diagram usually shows a single control loop which means it could only contains just one input (sensor to control system), just one output (control system to final element) or combination of both

Reference drawing
To have the loop diagram completed and to provide complete information, the following are list of data required along with its source/reference:

  • Instrument Terminal number.  Most instrument could be assumed to use (+) and (-). Terminals. Instrument which needs special arrangement such as smoke detector or instrument which in series loop requires manufacturer connection detail to make the cable is properly connected.

  • Junction box terminal number, this information could be obtained from  JB wiring connection

  • Marshaling terminal number, this information could be obtained from marshalling wiring connection.

  • I/O point detail information. Obtain this information from I/O assignment which is produced by system integrator or control system vendor.

The purpose of instrument loop diagram
It is used in checking of a correct installation and connection when tested during pre-commissioning, commissioning and also for trouble shooting during operations

 

Let me explain every loop and its characteristics one by one……………

A) PCS/DCS LOOP

1)PCS LOOP AI (ANALOG INPUT)

Characteristics of loop

a)Primary cable (cable laid from marshalling cabinet to JB) will be of 20 pair X 0.75 sqmm. And secondary cable (cable laid from JB to field) will be 1pair X 0.75 sqmm. shielded cables

b)There will not be any 24V power supply in general case {240V flow transmitters are exceptions}, the 4 to 20mA is fed from control room AI cards

c)The card will be for the purpose of control monitoring type like (Yokogawa Centum CS/ Centum VP, Siemens SimaticPCS7 Emerson delta V,ABB System800xA,Honeywell ST3000 and Experion PKS, GE OC4000,Rockwell PlantPAx, Invensys Foxboro IA series)

d)This loop will provide the present parameters of the system like current level, pressure, temperature, flow etc in terms of mA

e)The fuse used in the TB will be of the type Grey colour knife edge disconnect type fuse.

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2)PCS LOOP(AO) ANALOG OUTPUT:

Characteristics of loop 

a)Primary cable (cable laid from marshalling cabinet to JB) will be of 20 pair X 0.75 sqmm. And secondary cable (cable laid from JB to field) will be 1pairX0.75 sqmm. Shielded cables

b)There will not be any 24V power supply in general case {240V flow transmitters are exceptions}, the 4 to 20mA is fed from control room AO cards

c)The card will be of purpose of control/monitoring type like (Yokogawa Centum CS/ Centum VP, Siemens SimaticPCS7 Emerson delta V,ABB System800xA,Honeywell ST3000 and Experion PKS, GE OC4000,Rockwell PlantPAx, Invensys Foxboro IA series)

d)This loop will provide the command signal for controlling of the system like current level, pressure, temperature, flow control valves in terms of mA

e. The fuse used in the TB will be of the type Grey colour knife edge disconnect type fuse.

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3.PCS/DCS LOOP DIGITAL INPUT(DI)

Characteristics of loop 

a)Primary cable (cable laid from marshalling cabinet to JB) will be of 20 Core X 2.5 sqmm. And secondary cable (cable laid from JB to field) will be 2Core X 2.5 sqmm. shielded cables

b)There will be two 24V power supplies in general case, one for normally open condition status and another for normally closed condition status

c)The card will be of purpose of control/monitoring type like (Yokogawa Centum CS/ Centum VP, Siemens SimaticPCS7 Emerson delta V,ABB System800xA,Honeywell ST3000 and Experion PKS, GE OC4000,Rockwell PlantPAx, Invensys Foxboro IA series)

d)The fuse used in the feed through TB will be of the type Grey colour fuse TB with LED disconnect type fuse of value 50mA for the loop and two separate fuses of 1A for terminal board 24 volt DC power supply bus bar

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4) PCS/DCS LOOP DIGITAL OUTPUT (DO):

Characteristics of loop 

a)Primary cable (cable laid from marshalling cabinet to JB) will be of 20 Core X 2.5 sqmm. And secondary cable (cable laid from JB to field) will be 2Core X 2.5 sqmm. shielded cables

b)There will be two 24V power supplies in general case, one for open command and another for closed command for ON/OFF valve SOVs along with relay and another 24 V in the loop between TB and relay (thus total three 24V supply.)

c)The card will be of purpose of control/monitoring type like (Yokogawa Centum CS/ Centum VP, Siemens SimaticPCS7 Emerson delta V,ABB System800xA,Honeywell ST3000 and Experion PKS, GE OC4000,Rockwell PlantPAx, Invensys Foxboro IA series)

d)The fuse used in the feed through TB will be of the type Grey colour fuse TB with LED disconnect type fuse of value 1A for the loop and two separate fuses of 2A for terminal board 24 volt DC power supply bus bar

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B)ESD LOOP:

 1)ESD DIGITAL OUTPUT (DO) LOOP:

a)Primary cable (cable laid from marshalling cabinet to JB) will be of 20 Core X 2.5 sqmm. And secondary cable (cable laid from JB to field) will be 2Core X 2.5 sqmm. shielded cables

b)There will be one(not 2 as in case of DCS DO) 24V power supplies in general case, for open/close command for ON/OFF valve SOVs along with relay and another 24 V in the loop between TB and relay

c)The card will be of purpose of emergency shutdown type (Yokogawa Prosafe RS, Invensys triconex,Honeywell Fail safe controller as a part of Experion/TPS,siemens S7-400F,Emerson deltaV SMART SIS,ABB 800xA High Integrty SIS)

d)The fuse used in the feed through TB will be of the type Grey colour fuse TB with LED disconnect type fuse of value 1A for the loop and one fuse of 2A for terminal board 24 volt DC power supply bus bar

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2)ESD DIGITAL INPUT (DI) LOOP :

a)Primary cable (cable laid from marshalling cabinet to JB) will be of 20 Core X 1.5 sqmm. And secondary cable (cable laid from JB to field) will be 2Core X 1.5 sqmm. shielded cables

b)There will be one 24V power supplies (not 2 as in case of DCS DO) in general case, for open condition /closed condition.

c)The card will be of purpose of control/monitoring type like (Yokogawa Prosafe RS, Invensys triconex,Honeywell Fail safe controller as a part of Experion/TPS,siemens S7-400F,Emerson deltaV SMART SIS,ABB 800xA High Integrty SIS)

d)The fuse used in the feed through TB will be of the type Grey colour fuse TB with LED disconnect type fuse of value 50mA for the loop and one fuse of 2A for terminal board 24 volt DC power supply bus bar

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3)ESD ANALOG INPUT (AI):

Characteristics of loop

a)Primary cable (cable laid from marshalling cabinet to JB) will be of 20 pair X 0.75 sqmm. And secondary cable (cable laid from JB to field) will be 1pair X 0.75 sqmm. shielded cables

b)There will not be any 24V power supply in general case {240V flow transmitters are exceptions}, the 4 to 20mA is fed from control room AI cards

c)The card will be for the purpose of control monitoring type like (Yokogawa Prosafe RS, Invensys triconex,Honeywell Fail safe controller as a part of Experion/TPS,siemens S7-400F,Emerson deltaV SMART SIS,ABB 800xA High Integrty SIS)

d)This loop will provide the shutdown parameters of the system like current level, pressure, temperature, flow etc in terms of mA

e)The fuse used in the TB will be of the type Grey colour knife edge disconnect type fuse. Now a days, we use fuse along with knife edge for double protection

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C) FGS/FNG LOOP:

1)FNG ANALOG INPUT(AI) LOOP:

Characteristics of loop

a)Primary cable (cable laid from marshalling cabinet to JB) will be of 20 Triad X 1.5 sqmm. And secondary cable (cable laid from JB to field) will be 1Triad X1.5 sqmm. Shielded cables

b)There will be one 24V power supply and one 0 volt supply in general case, the 24 volt is fed for the first cable of the triad and 0 volt is fed to last cable of the triad

c)The card will be for the purpose of control monitoring type like (Yokogawa Prosafe RS, Invensys triconex,Siemens S7-400FH,Honeywell HS81-HSController,Emerson DeltaV SIS system)

d)This loop will provide the controlling/monitoring parameters of the system like gas LEL, flame quotient etc in terms of mA

e)The fuse used in the TB will be of the type Grey colour knife edge disconnect type fuse for 24 volt loop and knife edge for mA loop

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  1. 2)FNG DIGITAL OUTPUT (DO) LOOP :

    a)Primary cable (cable laid from marshalling cabinet to JB) will be of 40 Core X 2.5/1.5 sqmm. And secondary cable (cable laid from JB to field) will be 2Core X 2.5/1.0 sqmm. shielded cables

    b)There will be one(not 2 as in case of DCS DO) 24V power supplies in general case, for open/close command for ON/OFF valve SOVs along with relay

    c)The card will be of purpose of emergency shutdown type (Yokogawa Prosafe RS, Invensys triconex,Siemens S7-400FH,Honeywell HS81-HSController,Emerson DeltaV SIS system)

    d)The fuse used in the feed through TB will be of the type Grey colour fuse TB with LED disconnect type fuse of value 1A  for the loop and one fuse of 2A for terminal board 24 volt DC power supply bus bar

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    3)FNG DIGITAL INPUT (DI):

    a)Primary cable (cable laid from marshalling cabinet to JB) will be of 20 Core X 2.5 sqmm. And secondary cable (cable laid from JB to field) will be 2Core X 2.5 sqmm. shielded cables

    b)There will be one 24V power supplies (not 2 as in case of DCS DO) in general case, for open condition /closed condition.

    c)The card will be of purpose of control/monitoring type like (Yokogawa Prosafe RS, Invensys triconex,Siemens S7-400FH,Honeywell HS81-HSController,Emerson DeltaV SIS system)

  • d)The fuse used in the feed through TB will be of the type Grey colour fuse TB with LED disconnect type fuse of value 50mA for the loop and one fuse of 2A for terminal board 24 volt DC power supply bus barUntitled

    NB:

    • Generally AI/AO uses paired cable, knife edge fuse and no power supply.

    • DI/DO uses core cable, fuse TB with LED and 24 V supply in the loop with (or without) relay

    • DO/DI loop is assisted with minimum two 24 V power supply (one–24 V for ESD DI/FGS DI; two — 24V for ESD DO/ PCS DI / FGS DO and three — 24V for PCS DO)

    • FNG uses triad cable for AI FGS with a combination of knife edge and fused TB with LED having both 4-20mA loop and a 24 V loop

    • DI fuses will be generally of the rating 50 to 100 mA while that of DO will be of 1A

    • DO will be always having a relay

    • Card for PCS/DCS will in most cases-Yokogawa Centum CS/ Centum VP, Siemens SimaticPCS7 Emerson delta V,ABB System800xA,Honeywell ST3000 and Experion PKS, GE OC4000,Rockwell PlantPAx, Invensys Foxboro IA series;

      ESD -Yokogawa Prosafe RS, Invensys triconex;

      FNG will be Yokogawa Prosafe RS, Invensys triconex;

      RTU will be Yokogawa stardom

     

     

LASER LEVEL TRANSMITTERS

The laser level transmitter either uses triangulation, time of flight or confocal chromatic working principle

Triangulation

One method for accurately measuring the distance to targets is through the use of laser triangulation sensors. They are so named because the sensor enclosure, the emitted laser and the reflected laser light form a triangle.

The laser beam is projected from the instrument and is reflected from a target surface to a collection lens. This lens is typically located adjacent to the laser emitter. The camera views the measurement range from an angle that varies from 45 to 65 degrees at the centre of the measurement range, depending on the particular model.

Time of flight

This technique uses the time light takes to travel to a target and back, but the time for a single round trip is not measured directly. Instead, the strength of the laser is rapidly varied to produce a signal that changes over time. The time delay is indirectly measured by comparing the signal from the laser with the delayed signal returning from the target.

Confocal chromatic:

This uses use a white light source to accurately measure the distance to surfaces. The essence of our confocal chromatic imaging principle is the accurate detection of colours from light that is reflected back from target surfaces. The white light is focused onto the target surface by a multi-lens optical system. These lenses disperse the light into monochromatic stages (colours) along the measurement axis. A specific distance to the target is assigned to each colour’s wavelength in a factory calibration. Only the wavelength which is exactly focused on the target is used for the measurement. This light reflected from the target surface is transmitted from the probe, through a confocal aperture and onto a spectrometer which detects and processes the spectral changes and calculates distances. These distance measurements are transmitted at high speed via Ethernet communications protocol

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Some of the laser LT are below