THE FOUR BIGGEST MISTAKES IN INSTRUMENTATION AND HOW TO AVOID THEM

Hello to all of You. Happy New Year 2011.

This section describes some things that relate to mistakes in the installation of the instrument and how to fix it. May be useful for all.

Despite ongoing advancements in measurement and communications technology, instrumenting a process for feedback control remains a technical challenge. Today's sensors are certainly more sophisticated than ever before and fieldbus technology has simplified many installation issues considerably.Nonetheless, much can still go wrong with an instrumentation project.

The problem lies in the straightforward nature of instrumentation projects: each variable to be measured must be matched with the most appropriate sensor; the sensor must be installed, calibrated, and interfaced to the controller; and the information generated by the sensor must be filtered, factored, and filed in order to give the controller an accurate picture of what's going on in the process. This apparent simplicity is what often leads to a false sense of security and missteps in a minefield of potential problems. With that in mind, here are four circumstances you definitely want to avoid.

Mistake #1:

Selecting the wrong sensor

Technology mismatch

Although it's generally obvious what quantity needs to be measured in a flow, temperature, or pressure control application, it's not always obvious what kind of flowmeter, temperature sensor, or pressure gauge is best suited to the job.

A mismatch between the sensing technology and the material to be sensed can lead to skewed measurements and severely degraded control. This is especially true when measuring flow rates. All flow meters are designed to measure the rate at which a gas or liquid has been passing through a particular section of pipe, but not all flowmeters can measure all flows. A magnetic flowmeter or magmeter, for example, can only detect the flow of electrically conductive materials by means of magnetic induction. Non conductive fluids like pure water will pass through a magmeter undetected. Magmeters also have trouble distinguishing air bubbles from the fluid in the pipe. As a result, a magmeter will always yield an artificially high reading when bubbles pass through because it cannot sense the decrease in fluid volume caused by the presence of the bubbles. In a feedback loop, this occurrence would cause the controller to throttle back the flow rate more than necessary, preventing the required volume of fluid from reaching the downstream process. 

The problem gets even worse if the pipe is so full of air that it is only partially filled with liquid, a condition known as open channel. Although recent technological innovations allow certain magmeters to work in such a challenging environment, mechanical sensors such as turbines yield artificially high readings, since a trickle of fluid will move the meter's mechanism just as much as a full-pipe flow traveling at the same speed. On the other hand, mechanical sensors are not affected by the conductivity of the fluid, so they will sometimes work where magmeters fail. An even more challenging application is the measurement of pH in a caustic liquid such as the slurries found in paper mills.

A general-purpose pH probe made of corrodible materials might not only generate inaccurate data, it might die altogether, sometimes within a matter of days. Some probes, such as those offered by ABB, are specifically designed for such tough environments. They can double, triple, and even quadruple probe life in many applications. The trick is to find the right technology for the application, or to choose instruments that span a broader range of solutions. For example, new digital technologies allow some flowmeters to solve many more flow problems than their predecessors. Instrumentation vendors can be of help in avoiding the technology mismatch mistake. The best vendors train their sales people to assist with sensor selection and provide clients with easy-to-use selection guides. Some even offer extensive look-up tables based on product number, application, and serial numbers of past installations an especially useful service when replacing older products. Finding all the right parts can also be a challenge. Some instruments require specific housings, mounting hardware, and transmitters to forward the sensor's data to the controller. The right vendor can make all the difference by providing the entire assembly under a single catalog number. When it comes to temperature instrumentation, for example, training costs and purchasing effort are reduced when then vendor offers compatible probes and transmitters together as a package.

Paying too much (or too little)

Correct sensor selection is also a matter of balancing cost against performance. When there's a choice of equally effective technologies, the right choice is generally the cheapest one that gets the job done. Temperature instrumentation is a classic example. The two dominant technologies are resistance temperature detectors (RTDs) and thermocouples. An RTD consists of a metal plate or rod through which a current is passed. The resistance that the current encounters varies with the temperature of the metal. A thermocouple consists of two dissimilar metal wires joined together at one end. The voltage between the unjoined ends varies with the temperature of the joint. Both yield voltages that can be electronically interpreted to indicate the temperature of the surroundings. Thermocouples are generally cheaper, though less accurate than RTDs. If the application does not require particularly tight temperature control, an inexpensive thermocouple and a well-tuned PID loop should do the trick. But for processes that will only work correctly at very specific temperatures, it would be a mistake not to pay for the greater accuracy that an RTD affords. The cost of scrapping a batch of undercooked or scorched products would eventually dwarf any savings in equipment costs. A fast sensor can also be worth the extra cost. If the process requires a rapid succession of heating and cooling cycles, the temperature sensor must be able to generate a reading before it's too late to be of any use. Despite their cheaper pedigree, thermocouples tend to respond faster than RTDs so if speed is the only important performance issue, choose a thermocouple.

Mistake #2:

Installing sensors incorrectly

Placement

The best sensor can yield disappointing results if not installed correctly. Magmeters, for example, tend to generate noisy signals if the flow they're measuring is turbulent. Bends, junctions, and valves in a pipe can all cause turbulence, thus magmeters work best when installed in sections of straight pipe. Temperature sensors are also sensitive to placement. Even a highly accurate RTD tucked in the corner of a mixing chamber will only be able to detect the temperature of its immediate vicinity. If the mixing of the material in the chamber is incomplete, that local temperature may or may not represent the temperature of the material elsewhere in the chamber. Local temperature issues are the classic mistake that home heating contractors often make when installing household thermostats.

A mounting location closest to the furnace may be convenient for wiring purposes, but if that spot happens to be in a hallway or other dead air space, the thermostat will not be able to determine the average temperature elsewhere in the house. It will only be able to maintain the desired temperature in its immediate vicinity. The rest of the house may end up roasting or freezing.

 

Controller performance

Poor control also results when a sensor is installed too far away from the associated actuator. A distant sensor may not be able to measure the effects of the actuator's last move in time for the controller to make an educated decision about what to do next.

For example, consider the process of flattening hot steel into uniform sheets by means of two opposing rollers (see Figure 1). A thickness sensor downstream from the rollers gauges the sheet and causes the controller to apply either more or less pressure to

compensate for any out-of-spec thickness. Ideally, the thickness sensor should be located adjacent to the rollers to minimize the time between a change in roller pressure and the resulting change in the thickness measurement.
Figure-1.Poor Sensor Placement.
 












In this steel rolling example, D is the distance between the steel rollers and the thickness gauge downstream. If D is too large, the controller will take too long to correct thickness errors and may even make matters worse by becoming impatient.

Otherwise, the controller will not be able to detect any mistakes it may have been making soon enough to prevent even more of the sheet from turning out too thick or thin. Worse still, an appreciable dead time between the controller's actions and the resulting effects on the steel can cause the controller to become impatient. It will see no results from an initial control move, so it will make another and another some change begins to appear in the measurements reported by the sensor. By that time, the controller's cumulative efforts will have already overcompensated for the original error, causing an error in the opposite direction. The result will be a constant series of up and down swings in the roller pressure and a lot of steel ruined by lateral corrugations. Of course, overall process performance considerations aren't limited to how well the sensor feeds data to the controller during operation. Other factors to consider include ease of installation and time spent on the selection process, set up routines, and any labor-intensive maintenance. Fortunately, some instrumentation vendors design their sensors to accommodate such challenges, thereby improving performance before the system even goes on line. ABB, for instance, offers a swirl flowmeter that significantly reduces the need to install special upstream and downstream devices to accurately measure the flow through a pipe.

Protection

A steel mill is also a classic example of a harsh environment that can destroy inadequately protected sensors. Fortunately, the hazards posed by a manufacturing process are generally obvious and can often be overcome by installing a shield or choosing a rugged instrument. Often overlooked, however, are the effects of weather. Outdoor instruments can take quite a beating from rain, snow, hail, and falling ice.

Over time, outdoor instruments can fail slowly unless enclosed in appropriate housings. But even the housings themselves can cause problems for the enclosed instruments, particularly temperature sensors. If an RTD or thermocouple is mounted on the same piece of metal that supports the housing, the housing will work like a heat sink when the ambient temperature drops low enough. It will tend to draw heat out of the sensor and artificially lower its reading. The heat-sink effect will also tend to reduce the benefits of any internal heat that has been applied to prevent an instrument from freezing. 

Conversely, if a housing is equipped with fins intended to draw heat out of the enclosed sensor during warm weather, the fins must be mounted vertically.Otherwise, the warm air around the fins will not be able to rise away from the housing (see Figure 2).

Figurer-2 Poor Mounting.

Even the orientation of an instrument can affect its performance. Here, the sensor is enclosed in a housing designed to dissipate the heat it generates. The fins must be mounted vertically to allow warm air to escape.

Ground loops

While it's generally a good practice to insulate a sensor from the thermodynamic effects of its surroundings, it's absolutely critical to establish electrical isolation. The most common electrical problems due to poor installation are ground loops.

Ground loops occur when an extraneous current flows through the instrumentation wiring between two points that are supposed to be at the same voltage, but aren't (see Figure 3). The resulting electrical interference can cause random fluctuations in the sensors' output and may even damage the sensors themselves.

Instruments must be grounded to provide a reference voltage for the data signals they generate. Relying on earth ground is risky since not all of the earth shares the same electrical potential. The resulting currents will interfere with the sensors' signals.

As the name implies, ground loops most often occur when instruments and their cables are grounded improperly or not at all. Interestingly, the best way to isolate a plant's instruments from ground loop currents is to connect them together at one master grounding point. If that's not possible, a grid of grounding points must be spread throughout the plant, making sure that all points on the grid are at the same electrical potential. Insecure connections and inadequate wires can cause a voltage imbalance in the grid and ground loops between the instruments connected to it.

Mistake #3:

Generating gibberish Noise

Ground loops are not the only source of noise that can distort a sensor's readings. Radio frequency interference (RFI) is even more common in plants that use walkie talkies, pagers, and wireless networks extensively. RFI also results whenever a current changes, such as when an electromechanical contact or a static discharge generates a spark.

The sources of RFI noise must be eliminated or at least kept away from the plant's instrumentation if at all possible. Replacing electromechanical equipment with solid state devices will eliminate arc-generated RFI. Or, it may be sufficient to simply relocate switch boxes and relays to instrument-free areas of the plant. If all else fails, it may be possible to passively shield the source of the interference or the instruments being subjected to it. Ignoring the problem is not an option, especially when the source of the noise is ordinary house current. At 60 Hz, house current oscillates slowly enough to have an appreciable effect on some processes. Consider the steel rolling application again.

A 60 Hz noise superimposed on the output of the thickness gauge will pass through the controller and induce a 60 Hz oscillation in the roller pressure. If the sheet exits the rollers with a velocity of six feet per second, those oscillations will appear as bumps in the sheet appearing every tenth of an inch.. Whether those flaws are appreciable or not will depend on the amplitude of the original noise signal, the inertia of the rollers, and the tuning of the controller. PID controllers tuned to provide appreciable derivative action are particularly susceptible to the effects of measurement noise. They tend to react aggressively to every blip in the measurement signal to quickly suppress deviations from the setpoint. If a blip turns out to be nothing but noise, the controller will take unwarranted corrective actions and make matters worse.

Filtering

Unfortunately, it is not always possible to eliminate noise sources altogether. It is often necessary to filter the raw sensor data by averaging several samples together or by ignoring any changes less than some small percentage. Many digital instruments, like ABB's FSM 4000 flowmeter, come equipped with built-in filters. However, it is a mistake to think that number crunching alone can fix all measurement noise problems. Filtering tends to increase the time required to detect a change in the measured value and can even introduce spurious information into the signal. Worse till, it can mask the actual behavior of the process if it is overdone. It is generally more cost-effective in the long run to install sensors correctly and minimize the sources of interference than to rely strictly on mathematics to separate the data from the noise. When constructing a control loop, data filters should be applied in the final stages of the project, just before loop tuning.

Mistake #4:

Quitting too soon

Even when the data filters are in place and the last loop has been tuned, the project isn't over. There are some commonly neglected chores that should continue as long as the instrumentation system is in place. Calibration Most instrumentation engineers know that a sensor must be calibrated in order to associate a numerical value with the electrical signal coming out of the transmitter. Yet all too often, the instruments are calibrated just once during installation then left to operate unattended for years. The result is an insidious problem known as drift. A sensor's output tends to creep higher and higher (or lower and lower), even if the measured variable hasn't changed. Deposition on the sensing surfaces, corrosion in the wiring, and long term wear on moving parts can all cause an instrument to begin generating artificially high (or low) readings. As a result, the controller will gradually increase or decrease its control efforts to compensate for a non-existent error. Analog instruments are particularly susceptible to drift, much like old FM radios. The slightest nudge on the dial could cause the radio to lose its signal. With modern digital radios, the one true frequency for each station is digitally encoded at a fixed value. Similarly, modern instruments that employ digital signal processing can't be "nudged." They maintain the same calibration in the field as in the lab. Drift can also be reduced by the choice of sensing technology. Temperature sensors with mineral insolated cables, for example, are less prone to drift. Drift due to wear can be eliminated entirely by choosing instruments with no moving parts, like ABB's swirl and vortex meters. And even when drift cannot be eliminated, recalibrating every sensor in the plant at intervals recommended by their manufacturers can accommodate it. Unfortunately, project engineers are often so anxious to finish a job and get on with operating the process that they neglect such basic maintenance. Arguably the most challenging sources of drift are those that vary over time. Deteriorating probes and moving parts beginning to wear out can slowly change an instrument's accuracy. So, maintenance calibration is required periodically even if there are no known issues with the instrument. Some manufacturers are recognizing the time and efforts involved in traditional recalibration exercises and are designing instrumentation products to simplify matters. For example, the CalMaster portable calibrator from ABB provides in-situ calibration verification and certification of ABB's MagMaster electromagnetic flowmeters without requiring access to the flowmeter or opening the pipe. Instead,operator simply a CalMaster to the flowmeter's transmitter and a PC. A Windows interface guides the operator through a series of tests to evaluate the status of the transmitter, sensor, and interconnecting cables. The tests are complex, but so automated that the whole calibration routine can be accomplished in 20 minutes. Once the tests are complete, CalMaster will evaluate the measurements taken. If all satisfy the cali- bration requirements, then a calibration certificate can be printed either at that time or later. These certificates can then be catalogued in order to meet auditing and regulatory requirements such as ISO 9001.

An added benefit of CalMaster is that it can be used as a diagnostic and condition monitoring tool. It automatically stores all measured values and calibration information in its own database files for each meter, thus maintaining a calibration history log and making it easier to undertake longterm trend analysis. Detailed observation can give early warning of possible system failure, enabling the maintenance engineer to anticipate problems and take proactive remedial action. Such automated systems make routine verification of flowmeter calibration and the traceability of information much less cumbersome and costly than in the past. In the water industry, for example, such tasks formerly entailed mechanical excavation of the flowmeter resulting in a disruption of the water supply and a substantial investment in manpower and equipment. Planning for the road ahead All too often, an expansion project begins with weeks of wondering why the existing instrumentation system was constructed the way it was and why it doesn't match the project's original plans. To avoid this, future planning should be a part of your implementation process and also include thorough documentation of what's been done before. Someone will eventually want to expand the project and will need to know exactly which instruments have been placed where, what the instruments were supposed to be accomplishing, and how they were installed and configured. Even if the instrumentation system is never expanded, it will eventually have to be repaired. Wires break and sensors wear out. A good inventory of the system components will indicate what needs to be replaced, but that's only half the battle. Replacement parts must be acquired along with the technical specs necessary to install them correctly. An ongoing replacement parts program is a must. Either the original vendor must make provisions for stocking replacements (or upgrades) for all the instruments they've provided to date, or the project engineers must continue to monitor their suppliers to make sure that spare parts remain available. For hard-to-find instruments, it may even be necessary to maintain an in-house supply of replacement parts, just in case.   

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CONTROL THEORY BASICS

This article presents some of the basic concepts of control and provides a foundation from which to understand more complex control processes and algorithms later described in this module. Common terms and concepts relating to process control are defined in this section.

LEARNING OBJECTIVES

After completing this section, you will be able to:

Define control loop and describe the three tasks necessary for process control to occur:

• Measure

• Compare

• Adjust

 

Define the following terms:

• Process variable

• Setpoint

• Manipulated variable

• Measured variable

• Error

• Offset

• Load disturbance

• Control algorithm

List at least five process variables that are commonly controlled in process measurement industries. At a high level, differentiate the following types of control:

• Manual versus automatic feedback control

• Closed-loop versus open-loop control

THE CONTROL LOOP

Imagine you are sitting in a cabin in front of a small fire on a cold winter evening. You feel uncomfortably cold, so you throw another log on the fire. This is an example of a control loop. In the control loop, a variable (temperature) fell below the setpoint (your comfort level), and you took action to bring the process back into the desired condition by adding fuel to the fire. The control loop will now remain static until the temperature again rises above or falls below your comfort level.

THREE TASKS

Control loops in the process control industry work in the same way, requiring three tasks to occur:

Measurement

Comparison

Adjustment

 












In Figure, a level transmitter (LT) measures the level in the tank and transmits a signal associated with the level reading to a controller (LIC). The controller compares the reading to a predetermined value, in this case, the maximum tank level established by the plant operator, and finds that the values are equal. The controller then sends a signal to the device that can bring the tank level back to a lower level a valve at the bottom of the tank. The valve opens to let some liquid out of the tank. Many different instruments and devices may or may not be used in control loops (e.g., transmitters, sensors, controllers, valves, pumps), but the three tasks of measurement, comparison, and adjustment are always present.
As in any field, process control has its own set of common terms that you should be familiar with and that you will use when talking about control technology.

PROCESS VARIABLE

A process variable is a condition of the process fluid (a liquid or gas) that can change the manufacturing process in some way. In the example of you sitting by the fire, the process variable was temperature. In the example of the tank in Figure, the process variable is level. Common process variables include:

Pressure

Flow

Level

Temperature

Density

Ph (acidity or alkalinity)

Liquid interface (the relative amounts of different liquids that are combined in a vessel)

Mass

Conductivity

 

SETPOINT

The setpoint is a value for a process variable that is desired to be maintained. For example, if a process temperature needs to kept within 5 °C of 100 °C, then the setpoint is 100 °C. A temperature sensor can be used to help maintain the temperature at setpoint. The sensor is inserted into the process, and a controller compares the temperature reading from the sensor to the setpoint. If the temperature reading is 110 °C, then the controller determines that the process is above setpoint and signals the fuel valve of the burner to close slightly until the process cools to 100 °C. Set points can also be maximum or minimum values. For example, level in tank cannot exceed 20 feet.

 

MEASURED VARIABLES, PROCESS VARIABLES, AND MANIPULATED VARIABLES

In the temperature control loop example, the measured variable is temperature, which must be held close to 100 °C. In this example and in most instances, the measured variable is also the process variable. The measured variable is the condition of the process fluid that must be kept at the designated setpoint. Sometimes the measured variable is not the same as the process variable. For example, a manufacturer may measure flow into and out of a storage tank to determine tank level. In this scenario, flow is the measured variable, and the process fluid level is the process variable.

The factor that is changed to keep the measured variable at setpoint is called the manipulated variable. In the example described, the manipulated variable would also be flow.
   

ERROR

Error is the difference between the measured variable and the setpoint and can be either positive or negative. In the temperature control loop example, the error is the difference between the 110 °C measured variable and the 100 °C setpoint that is, the error is 10 °C.

The objective of any control scheme is to minimize or eliminate error. Therefore, it is imperative that error be well understood. Any error can be seen as having three major components. These three components are shown in the figure on the following page.
 

Magnitude

The magnitude of the error is simply the deviation between the values of the setpoint and the process variable. The magnitude of error at any point in time compared to the previous error provides the basis for determining the change in error. The change in error is also an important value.

 

Duration

Duration refers to the length of time that an error condition has existed.

 

Rate of Change
The rate of change is shown by the slope of the error plot

OFFSET
Offset is a sustained deviation of the process variable from the setpoint. In the temperature control loop example, if the control system held the process fluid at 100.5 °C consistently, even though the setpoint is 100 °C, then an offset of 0.5 °C exists.
 

LOAD DISTURBANCE

A load disturbance is an undesired change in one of the factors that can affect the process variable. In the temperature control loop example, adding cold process fluid to the vessel would be a load disturbance because it would lower the temperature of the process fluid.

CONTROL ALGORITHM

A control algorithm is a mathematical expression of a control function. Using the temperature control loop example, V in the equation below is the fuel valve position, and e is the error. The relationship in a control algorithm can be expressed as:
 

Control algorithms can be used to calculate the requirements of much more complex control loops than the one described here. In more complex control loops, questions such as “How far should the valve be opened or closed in response to a given change in setpoint?” and “How long should the valve be held in the new position after the process variable moves back toward setpoint?” need to be answered.

MANUAL AND AUTOMATIC CONTROL

Before process automation, people, rather than machines, performed many of the process control tasks. For example, a human operator might have watched a level gauge and closed a valve when the level reached the setpoint. Control operations that involve human action to make an adjustment are called manual control systems.

Conversely, control operations in which no human intervention is required, such as an automatic valve actuator that responds to a level controller, are called automatic control systems.

  

CLOSED AND OPEN CONTROL LOOPS

A closed control loop exists where a process variable is measured, compared to a setpoint, and action is taken to correct any deviation from setpoint. An open control loop exists where the process variable is not compared, and action is taken not in response to feedback on the condition of the process variable, but is instead taken without regard to process variable conditions. For example, a water valve may be opened to add cooling water to a process to prevent the process fluid from getting too hot, based on a pre-set time interval, regardless of the actual temperature of the process fluid.

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The Importance of Process Control

PROCESS...
Process as used in the terms process control industry, refers to the methods of changing of refining raw materials to create end products. The raw materials, which either pass through or remain in a liquid, gaseous, or slurry (a mix of solids and liquids) state during the process, are transferred, measured, mixed, heated or cooled, filtered, stored, or handled in some other way to produce the end product.
Process industries include the chemical industry, the oil and gas industry, the food and beverage industry, the pharmaceutical industry, the water treatment industry and the power industry.

PROCESS CONTROL
Process control refers to the methods that are used control process variables when manufacturing a product. For example, factors such as the proportion of one ingredient to another, the temperature of the materials, how well the ingredients are mixed and the pressure under which the materials are held can significantly impact the quality of an end product. Manufacturers control the production process for three reasons:
Reduce variability
Increase efficiency
Ensure safety

Reduce Variability 
Process control can reduce variability in the end product, which ensure a consistently high quality product. Manufacturers can also save money by reducing variability. For example, in a gasoline blending process, as many as 12 or more different components may be blended to make a specific grade of gasoline. If the refinery does not have precise control over the flow of the separate components, the gasoline may get too much of the high-octane components. As a result, customers would receive a higher grade and more expensive gasoline than they paid for, and the refinery would lose the money. The opposite situation would be customers receiving a lower grade at a higher price.
Reducing variability can also save money by reducing the need for product padding to meet required product specifications. Padding refers to the process of making a product of higher-quality than it needs to be to meet specifications. When there is variability in the end product (i.e.,when process control is poor), manufacturers are forced to pad the product to ensure that specifications are met, which adds to the cost. With accurate, dependable process control, the setpoint (desired or optimal point) can e moved closer to the actual product specification and thus save the manufacturer money. 

Increase Efficiency
Some processes need to be maintained at a specific point to maximize efficiency. For example, a control point might be the temperature at which a chemical reaction takes place. Accurate control of temperature ensures process efficiency. Manufacturers save money by minimizing the resources required to produce the end product.

Ensure Safety
A run-away process, such as an out-of-control nuclear or chemical reaction, may result if manufacturers do not maintain precise control of all of the process variables. The consequences of a run-away process can be catastrophic. Precise process control may also be required to ensure safety. For example, maintaining proper boiler pressure by controlling the inflow of air used in combustion and the outflow of exhaust gases is crucial in preventing boiler implosions that can clearly threaten the safety of workers.

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Spider System Hydraulics Control

Spider System Hydraulics Control

Spider System Hydraulics Control
Spider is meant here is not a family of eight-legged insects that are highly toxic and deadly if bitten by it.
Spider what I mean is a system control hydraulic which require a large force or torque for stirring small pieces of wood (chips) inside the digester or Impbin according to the desired speed to achieve the desired amount of production in the process to produce pulp in our factory. Control system used is called Spider Hydraulic Control System (Hagglunds). This control system direct control of two pumps which serve to drain the oil in the system in order to increase oil pressure above 250 bar antecedent control by a proportional valve. The larger the orifice of the proportional valve which is open the greater the amount of oil which passed into the system so that the oil pressure levels rise. With this high pressure control rotational speed of the digester and Impbin be in control. Controlling the maximum speed in our factory is 20 rpm. For treatment of a main board / card spider who does not much can be done. We do care only at every annual shut down. Flushing with clean air and re-check all terminal connections. To avoid loss of process pulp production we have to prepare a spare for main board.

Impbin

  

In the Company of our systems are installed in 6 locations: 3 in PM9 Impbin, HP-feeder and Outlet Devices Digester and 3 more in PM8 Impbin, HP-feeder and the Outlet Device Digester
For the PM9 has been run since 2007 and for PM8 still need to wait for tie ins to the Digester area.
The Spider problem that occurred in our company in Pulp Making-9 are:
1-Monitor in the control panel remains black while the system runs and can not be in control.
2-Alarm appears on monitor and the system stop, can not run anymore.

At first we felt confused handling although this system is simple but unprecedented. We try to replace the mainboard with a spare from Impbin PM8 (not yet run). We try to enter the parameters required (number of parameters about 22 pages type of A4 paper)
I will explain what we've done.
To save time and reduce the loss of production then we immediately replace it with a new card. We bring the damaged card to the office for the analysis of the problem. Connect spider control with a computer and receive data from the spider. To analyze and try to reset several times and re-enter the correct data, try to simulate with the simulator 4 ~ 20mA and connected output with proportional valve. To avoid and reduce the loss of production we have provided training to all members of the instrument.

Spider simulation

How to grab data from Spider Control Panel (for Back up)
1-Connect power cable (220Vac,50Hz).
2-Connect output adapter 24Vdc to Spider control panel and turn on spider.
3-Connect cable usb to serial RS232 to Spider (serial RS232 side).
4-Connect Computer with cable usb to serial RS232 (usb side)
5-Open file "spidercom2.exe" in your computer.
6-Click tab "PARAMETER" than click "RECEIVE".
7-Wait a few moments. Computer will read and receive data from Spider Control Panel and when finished will display on monitor computer "DONE". When starting  receive data, the lights in cable USB / RS232 going on. Till to exit the word DONE in the computer than the lights off.
8-To view the data which has been in the store we could open with a click "DISPLAY" and then click "PARAMETERS". The file will appear and you can check all the existing data in the Spider Control Panel. Save your file before it by clicking "FILE" then "SAVE AS" as a unix file names in your computer's hard drive, for example,  "PM9Impbin". Files that are stored will have a ext. s2p or "PM9Impbin.s2p".
9-Completed.


How to send data from your computer to Spider Control Panel.
1-Connect cable USB to RS232 to a computer and Spider Control Panel.
2-Open the file has been updated to upload (save to Spider Control Panel) for example: PM9Impbin.s2p.
Once open, make sure the correct data and then we save it to Spider Control Panel Click "PARAMETERS" then click "Transmit".
3-When the transmit is completed it will come out the word "transmit okay" in your computer. The lights on the usb cable / RS232 going off.
4-To complete the process transmits the Spider Control Panel needs to be reset. Press the "RESET" once and wait for Spider Control boot ..
5-Spider Control Panel is ready to be operated by the process.
6-Completed.


I created this article so that we can share knowledge together. Much remains to be added because this is only a short writing course. If anyone wants to ask I'll try to answer.

Thank you.

Spider main board

Impbin at night

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My Instrumentation Experience at IKPP

Hello...nice to meet you.
I hope you are glad reads my article.

May I introduce my self. Around year 1993, my first job is at PT.Indah Kiat Pulp & Paper Indonesia Pekanbaru Perawang mill. We are at placed at project kvaerner PM8. We have done many matters has liked instruments installation, pulled signal and power cable, termination, tube installation, setting parameter, calibrate control valve, signal test and loop test. Since this project i had learn from many article that support my job and my skill.

Pulp Making-9

Any of them is "The Seven Habits of Highly Successful Control Engineers" presented by George Buckbee,P.E.
In this article I will sharing with you that highly successful control engineers didn't become that way by accident. The most successful engineers develop habits that improve results and recognition of those results. This paper addresses specific habits that you can develop or enhance to be more successful.

The 7 Habits listed in this paper were developed from over 20 years, working with thousands of control engineers around the world. Some people who struggled to identify their results and others who had great results, but couldn't get recognition. In this article, we'll look at some of the habits that have ensured success for the most successful of these engineers.

7 Habits  The 7 Habits listed in this paper are: 1.   Know the Process. 2.   Focus only on the Most Important Things 3.   Document the Baselines 4.   Use Tools to be More Effective 5.   Network and Communicate Results 6.   Keep Learning 7.   Share Your Knowledge In the pages that follow, we'll look at each one of them, and provide some suggestions for how you can improve your own rate of success. Habit 1 - Know the Process Knowing the process is the first and most important habit for control engineers. To be effective in the automation and control of a process, you must first have a thorough understanding of the process. To develop process knowledge takes time and effort. Start by studying process flow diagrams and P&IDs. Trace the primary product as it flows through the process,  highlighting it on drawing with a colored marker. Talk to operators.They work with the process day in and day out.  They understand a lot about how the  process normally behaves.They also know about the abnormal, unusual things that can happen during equipment failures,  shutdowns,  start-ups, and shift changes. The process doesn't always behave according to the text book. Make sure you know what to expect in abnormal situations.  With a little bit of process knowledge, tools like Process Interaction Mapping can help you to pinpoint the source of control upsets. Habit 2 - Focus on the Most Important Things  It is so easy to lose focus in a plant environment. There are daily disasters, fire-fighting,management meetings,projects,and a hundred other distractions. The challenge,of course,is to stay focused on those activities that will deliver the most value to the business. As Stephen Covey says, in First Things First, "The main thing is to keep the main thing the main thing".  In a process manufacturing environment, the "Main thing" is usually some combination of these factors: •     Unit Cost •     Production Rate •     Quality •     Energy Costs •     Reliability •     Environmental & Safety It will be very difficult to prove success if you cannot link your work to one or more of these factors. Habit 3 - Document the Baseline If you don't know where you started, how will you know how far you have come? I have seen people make this mistake many times over in my career. Successful engineers always take time to understand the starting point. The starting point should always be measured in business terms. You can supplement with some technical measures, but you should always establish a good baseline of business metrics, such as those mentioned above. Discuss the baseline conditions with an operations manager or financial person, to make sure that you understand what the numbers mean. This also helps ensure that you are working on the right things. Be sure to use the exact same methods to measure these metrics. If they measure profit in dollars per truckload, then you should, too. The technical measures are a good supplement, but only if they can be linked to the business metrics. For example, if you are trying to improve quality (reduce % rejects, for example), it may be a good idea to track a  technical metric such as variability. You can make a strong case that reduced variability has a direct impact on  reducing the amount of reject material. Habit 4 -  Improve Your Effectiveness with the Right Tools  I can admit that, as an engineer, I love to dig in to the details, and use my engineering knowledge to sniff out the root cause of a problem. This is part intuition, part experience, and partly that engineering mindset. If you love to solve problems, it can be easy to overlook that there may be some much simpler ways to get the job done. For example, people often ask how to find control loops that are performing poorly. We could go through the exercise of looking at each loop, analyzing it, and coming up with a list of the top 10 issues. Chances are that this would take a long time, because I would definitely get side-tracked into solving some of these problems along the way. To make this job go much faster, I use the control loop monitoring tools in PlantTriage. Based on a few key metrics, PlantTriage will give me a top 10 list automatically. It already has all the data, because it monitors the process 24 hours a day. And sometimes, you have to get your ego out of the way. All control engineers think they can tune loops quickly by hand. "Quickly", yes."Properly", not very often. Use a software tool to get the answers quickly and properly. These days, most companies have downsized their engineering staffs considerably. You simply don't have the time to be inefficient at any aspect of your job. Habit 5 - Communicate Results & Network This is probably the most important of these 7 habits. If you do great things, and nobody knows what was done, you have lost. Networking is a critical part of this. I'm not talking about computer networks, but people. Make sure you have credibility with a wide array of people. Think outside your normal workday routine. Set up lunch meetings with some of these people. The Plant IT Manager Your Counterparts in Other Departments. The Plant Financial Guru. Instrument Techs. Operations Managers. Purchasing Agents.This will be a challenge at first. But you will find that this helps you to develop stronger relationships in the plant. These relationships will be helpful as you communicate your results.  When you get some good results, you will need to communicate them clearly, concisely, and in business terms. Remember the base lining discussion above? Go back to your baseline measurements, and show how your work had an influence on the bottom line. When it comes to communicating, keep it simple. Don't write a 200-page report. Nobody will read it. Instead, send a short email with "Before and After" pictures, and just a little bit of back-up material. The subject line of the email should be something like: "$120,000 Savings on the De-Chlorinator". That email will be opened, read, and forwarded to others. How much value can you bring? It certainly depends on your role. With some effort, a typical control engineer should be able to document between 6 and 10 times their annual salary in savings.This may come from  any combination of the business results areas listed in the baseline section. Habit 6 - Keep Learning Never stop learning. One of the great mentors in my career was Virgil Colavitti. Virgil had been working in the same plant for over 40 years. He seemed to know the inner workings of every machine, instrument, valve, transformer, and other device under the sun. In working with him, I learned why. He had a natural curiosity, and he was never afraid to ask questions. In a group of people, he would often say, "I wonder how that works..." And sure enough, someone would explain it. Today, you have a huge number of training resources available. You can take training course in your plant,at a training center,or over the web. You can quickly find books and articles that delve into every possible subject. Be careful! Make sure you are working with a credible source of information. Published authors and established companies are great source of information. But some on-line sources have little editorial control, and their accuracy is questionable at best. ExperTune, of course, has been widely recognized for over 20 years as a source of deep knowledge in the field of process control.  ExperTune's training courses are practical, hands-on training, designed to help you be extremely effective at managing control loops in your facility. Habit 7 - Share Your Knowledge Typically, 20% to 30% of all control loops are running in Manual. That should be shocking. Why don't people step up and take notice? One reason may be that they simply don't understand the significance. Process control is not well-understood by "lay people". Twenty years after paying for my college education, my parents still have only a vague  understanding of what it is that a process control engineer actually does. Even within the plant environment, there is often a vague mystery  associated with process control. We use strange terminology, and talk about abstract things like "dynamics", "dead time", and "derivative".  Many plant people are simply confused by the topic. Sharing your knowledge with others can help to make you and them more effective. For your own success, if people understand what you do, they will have a better appreciation of the value you bring to the company. It's hard to  downsize someone that brings a lot of value! Because other people often  have limited process control knowledge, even sharing a little bit of your  knowledge may be tremendously useful. For a while in my career, we used a lot "single point lesson plans". These were simple, one-page training aids. So you could do a short 3-minute training session on topics like: "What is Cascade Control?", "Why we use filters on our instruments", "How to test the over-speed interlock","How to prevent valves from sticking". Whenever I was called in to resolve a problem at night,I always followed up with a single-point lesson the following day. I figured that I would not need to be called in again on the same problem if 10 other people knew how to  resolve it.You can be as formal or as informal as you wish. The key point is to help spread some knowledge around. Conclusions Your results will improve and be recognized if you pay attention to the 7   Habits discussed in this article.  A typical control engineer should be able to document between 6 and 10 times their annual salary in savings.  Documented results are key to success. Make sure you have the right tools and training to be successful in your company. About PlantTriage PlantTriage is a Plant-Wide Performance Supervision System that optimizes  your entire process control system, including instrumentation, controllers, and control valves. Using advanced  techniques, such as Active Model Capture Technology,  PlantTriage can identify, diagnose, and prioritize improvements to your process.

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