DCS – Distributed Control System

A DCS is typically used to describe a system that controls a process; that is, something that involves moving fluids, like a waste water treatment plant or a refinery.

SCADA – Supervisory Control And Data Acquisition

This usually describes the control system for an automated manufacturing facility like an assembly line for a furniture maker.

PLC – Programmable Logic Controller

This is the computer that receives data from sensors and controls machinery. It can perform as the core processor for a DCS or a SCADA system.

Popular PLCs are Rockwell (Allen-Bradley), Siemens, Modicon and Delta V.

PAC – Programmable Automation Controller

This is Rockwell’s new for their ControlLogix computers.

HMI – Human Machine Interface

An HMI is a terminal that is used by plant operators to control the plant. It typically shows a graphic representation of the plant and allows the operator to start and stop motors, look at tank levels, etc. The graphics are usually very similar to the P&ID drawings of the plant.

An HMI is part of a SCADA or a DCS.

Typical HMIs are based on RSView32, FactoryView (Rockwell) or Wonderware. Other PLC manufacturers have their own HMI software.

OIT – Operator Interface Terminal

This device is a self-contained screen that is located near the equipment that it controls. All OITs are HMIs, but not necessarily vice-versa.

Globe Valves are named for their spherical body shape with the two halves of the body being separated by an internal baffle. This has an opening that forms a seat onto which a movable plug can be screwed in to close (or shut) the valve. The plug is also called a disc or disk. In globe valves, the plug is connected to a stem which is operated by screw action in manual valves. Typically, automated valves use sliding stems. Automated globe valves have a smooth stem rather than threaded and are opened and closed by an actuator assembly. When a globe valve is manually operated, the stem is turned by a handwheel.

Although globe valves in the past had the spherical bodies which gave them their name, many modern globe valves do not have much of a spherical shape. However, the term globe valve is still often used for valves that have such an internal mechanism. In plumbing, valves with such a mechanism are also often called stop valves since they don’t have the global appearance, but the term stop valve may refer to valves which are used to stop flow even when they have other mechanisms or designs.

Globe valves are used for applications requiring throttling and frequent operation. For example, globe valves or valves with a similar mechanism may be used as sampling valves, which are normally shut except when liquid samples are being taken. Since the baffle restricts flow, they’re not recommended where full, unobstructed flow is required.

Body

The main pressure containing structure of the valve and the most but easily identified as it forms the mass of the valve. It contains all of the valve’s internal parts that will come in contact with the substance being controlled by the valve. The bonnet is connected to the body and provides the containment of the fluid, gas, or slurry that is being controlled.

Globe valves are typically two-port valves, although three port valves are also produced. Ports are openings in the body for fluid flowing in or out. The two ports may be oriented straight across from each other on the body,[5] or oriented at an angle such as a 90° angle. Globe valves with ports at such an angle are called angle globe valves. A globe valve can also have a body in the shape of a y’.

Bonnet

Provides leakproof closure for the valve body. The threaded section of stem goes through a hole with matching threads in the bonnet. Globe valves may have a screw-in, union, or bolted[7] bonnet. Screw-in bonnet is the simplest bonnet, offering a durable, pressure-tight seal. Union bonnet is suitable for applications requiring frequent inspection or cleaning. It also gives the body added strength. A bonnet attached with bolts is used for larger or higher pressure applications. Bonnets also contain the packing, which is a wearable material that maintains the seal between the bonnet and the stem during valve cycling.

The closure member of the valve. Plugs are connected to the stem which is slid or screwed up or down to throttle the flow. Plugs are typically of the balance or unbalanced type. Unbalanced plugs are solid and are used with smaller valves or with low pressure drops across the valve. The advantages are simpler design, with one possible leak path at the seat and usually lower cost. The disadvantages are the limited size; with a large unbalanced plug the forces needed to seat and hold the flow often becomes impractical. Balanced plugs have holes through the plug. Advantages include easier shut off as the plug does not have to overcome static forces. However, a second leak path is created between the plug and the cage, cost is generally higher.

Stem

The stem serves as a connector from the actuator to the inside of the valve and transmits this actuation force. Stems are either smooth for actuator controlled valves or threaded for manual valves. The smooth stems are surrounded by packing material to prevent leaking material from the valve. This packing is a wearable material and will have to be replaced during maintenance. With a smooth stem the ends are threaded to allow connection to the plug and the actuator. The stem must not only withstand a large amount of compression force during valve closure, but also have high tensile strength during valve opening. In addition, the stem must be very straight, or have low run out, in order to ensure good valve closure. This minimum run out also minimizes wear of the packing contained in the bonnet, which provides the seal against leakage. The stem may be provided with a shroud over the packing nut to prevent foreign bodies entering the packing material, which would accelerate wear.

Cage

The cage is part of the valve that surrounds the plug and is located inside the body of the valve. Typically, the cage is one of the greatest determiners of flow within the valve. As the plug is moved more of the openings in the cage are exposed and flow is increased and vice versa. The design and layout of the openings can have a large effect on flow of material (the flow characteristics of different materials at temperatures, pressures that are in a range). Cages are also used to guide the plug to the seat of the valve for a good shutoff, substituting the guiding from the bonnet.

Seat ring

The seat ring provides a stable, uniform and replaceable shut off surface. Seat rings are usually held in place by pressure from the fastening of the bonnet to the top of the body. This pushes the cage down on the lip of the seat ring and holds it firmly to the body of the valve. Seat rings may also be threaded and screwed into a thread cut in the same area of the body. However this method makes removal of the seat ring during maintenance difficult if not impossible. Seat rings are also typically beveled at the seating surface to allow for some guiding during the final stages of closing the valve.

Economical globe valves or stop valves with a similar mechanism used in plumbing often have a rubber washer at the bottom of the disc for the seating surface, so that rubber can be compressed against the seat to form a leak-tight seal when shut.

Materials

Typically globe valves are made of metallic alloys, although some synthetic materials are available. These materials are chosen based on pressure, temperature, controlled media properties. Corrosive and/or erosive process streams may require a compromise in material selection or exotic alloys or body coatings to minimize these material interactions and extend the life of the valve or valve trim components. Typically, carbon steel alloys are specified for noncorrosive applications. Other alloys such as Hastelloy, Monel, Inconel and others are available.

Packing material must also be considered during valve selection. Typically the requirement for a low friction packing conflict with a durable material that will provide low maintenance requirements during service life. Corrosive applications can further complicate packing material selection as the typical packing materials may or may not be compatible with the processed materials. Typically graphite or PTFE is used due to its low friction coefficient. Enviro-seal applications also have the availablilty of constant applied force (live-load) packing. While more complex, it allows for constant packing force load throughout the life of the packing material. This packing helps meet contemporary environmental laws.

(text and images courtesy of Wikipedia)

Ball valves are used extensively in industry because they are very versatile, supporting pressures up to 10,000 psi and temperatures up to 200 Deg C. Sizes from 1/4″ to 12″ are readily available. They are easy to repair, and operate manually or by actuators.

The body of ball valves may be made of metal, plastic or metal with a ceramic center. The ball is often chrome plated to make it more durable.
[edit] Types of ball valve

Types of Ball Valves

There are five general body styles of ball valves: single body, three piece body,split body, top entry, and welded.

There are three general types of ball valves according to bore

* A full port ball valve has an over sized ball so that the hole in the ball is the same size as the pipeline resulting in lower friction loss. Flow is unrestricted, but the valve is larger. This is not required for general industrial applications as all types of Valves used in industry like Gate Valves, Plug Valves, Butterfly valves etc have restrictions across the flow and does not permit full flow. This leads to excessive costs for full bore ball valves and is genearlly a unneccessary spending for customers.

* In reduced port ball valves, flow through the valve is one pipe size smaller than the valve’s pipe size resulting in flow area becoming lesser than pipe. But the flow discharge remains constant as it is a Multipler factor of Flow discharge(Q) is equal to Area of Flow (A) into Velocity (V). A1V1=A2V2 i.e the Velocity increase with reduced Area of flow and Velocity decreases with increased area of flow.

* A V port ball valve has either a ‘v’ shaped ball or a ‘v’ shaped seat. This allows the orifice to be opened and closed in a more controlled manner with a closer to linear flow characteristic. When the valve is in the closed position and opening is commenced the small end of the ‘v’ is opened first allowing stable flow control during this stage. This type of design requires a generally more robust construction due to higher velocities of the fluids, which would quickly damage a standard valve.

* A trunnion ball valve has a mechanical means of anchoring the ball at the top and the bottom, this design is usually applied on larger and higher pressure valves (say, 4″ and above 600 psi and above).

Manually operated ball valves can be closed quickly and thus there is a danger of water hammer. Some ball valves are equipped with an actuator that may be pneumatically or motor (electric) operated. These valves can be used either for on/off or flow control. A pneumatic flow control valve is also equipped with a positioner which transforms the control signal into actuator position and valve opening accordingly.

American Institute of Aeronautics and Astronautics

American Society of Mechanical Engineers

American Institute of Chemical Engineers

Architectural Engineering Institute

Biomedical Engineering Society

Institute of Electrical and Electronics Engineers

Society of Petroleum Engineers

Wind power has been growing at a pace that rivals that of the solar industry. The worldwide generating capacity of wind turbines has grown more than 25% every year for the past decade, reaching nearly 60,000 MW in early 2006. In Europe, the growth has been phenomenal. In 1994, the total installed wind generated power capacity of the European Union nations was 1700 MW. In 2005, wind generators produce more than 40,000 MW. Germany alone has more than 18,000 MW of wind power capacity, thanks to a politically aggressive system of construction. The northern state of Germany, Schleswig-Holstein, currently provides one quarter of its electrical demand with more than 2400 wind turbines, and in some months wind power provides more than half of the state’s electricity.

Spain has 10,000 MW of wind capacity. Denmark has 3000 MW. Great Britain, the Netherlands, Italy and Portugal each have more than 1000 MW.

In the U.S., the wind power industry has also accelerated dramatically. Power generation capacity due to wind has increased 36% recently. Even though wind turbines produce only 0.5% of the nations electricity, the potential for expansion is really quite large, especially when the Great Plains states are considered. North Dakota, for example, has greater wind power resources than Germany, but only 98 MW of generating capacity is installed there. If the U.S. constructed enough wind farms to fully tap those resources, the turbines could generate as much as 11 trillion kWh of electricity, or nearly 3 times the total amount produced from all energy sources in the nation last year.

The reservations about wind power come partly from utility companies that are reluctant to use the new technology. Although opinions vary on how wind turbines will affect landscape use, everyone agrees that they must be balanced against the social cost of the alternatives. Because our energy needs are growing very quickly, rejecting wind farms will often result in the construction or expansion of fossil fuel burning power plants that have a much more damaging environmental effect.

But the reality of life in the technical world is that, first, you have to get a job. Getting a job as an engineer starts first with getting the attention of a potential employer and that is where a professional resume comes into play.

I want to give you a couple of resume writing tips before you start writing a resume. You will have to do some research to find what keywords are appropriate and pertinent to your field.

Resume Keywords Rule

Look at the online postings for engineering jobs. Find all of the keywords that apply to you and your experience, such as PLC, motors, drives, automation and so on. Make a list of these before you start writing a resume.

Don’t worry about the format of the resume at this stage. A simple list is fine.

Most resumes are placed online and recruiters and companies search for keywords first. It won’t do you any good to have a beautiful resume format if your resume never shows up in the searches.

Next, make a list of your skills and abilities. Use your keywords.

After that, list all of your previous employers in reverse chronological order. Make sure the dates are accurate. Under each employer, list what duties you performed. Again, use your keywords. Don’t be too humble here; I have found that most of the resumes I have reviewed understate the applicant’s ability.

How To Write A Resume The Easy Way – Use A Resume Writing Service To Create A Professional Resume

At this point, you can make a decision. You can choose to write your resume yourself, using eloquent phrases that flow trippingly off the tongue and impress the potential employer with your extensive knowledge of the English language.

Get Resume Help and Resume Tips

Or, you can hire a professional resume writing service to make a good, solid advertisement for you. They can provide the resume help you need.

After all, a resume is an advertisement; we don’t want to forget that. Unless you have experience in advertising, you will probably be much further ahead by paying someone else for his or her expertise in this matter.

You wouldn’t have to worry about the resume format, getting help with your resume, searching online for resume tips or some free resume template.

These people are writers and they do this for a living. Granted, there are quite a few companies on the Internet that claim to be able to write resumes, but based on some their websites, I have my doubts.

I ran across a company called ResumeWriters.com. Their website looks really sharp, modern and businesslike. Their copy is crisp and concise. They even guarantee that the resume they right for you will land you an interview in 30 days or they will rewrite it for you.

They have a number of sample resumes online from electrician to optical engineer.

Their prices are very reasonable, especially when you consider that the basic resume format and structure won’t change for a few years. That means you probably won’t have to hire another resume service for a long time

Take a look at resumewriters.com here.

Best of luck!

Learn Who You Can Trust to Provide Accurate Information
Gathering accurate information is an important aspect of troubleshooting. However well meaning, some of the people you deal with will not provide accurate information.
This may seem like stating the obvious, but always try to verify all the information you are given.

Never Compromise The Safety Of The Machine Or The Workers
Many times when you are charged with troubleshooting a system, you are placed in a position of authority. Be aware that others will look to you to provide direction. Make sure that as you provide that direction, you are giving their personal safety your highest priority.

Listen to Your Boss
If he tells you to call a vendor, don’t fiddle around with trying to fix it yourself – call the vendor.

Don’t Let Your Ego Get in the Way
Your job is to fix the equipment. If it means making a phone call to someone you dislike, admitting that you made a mistake in your initial diagnosis, just do it and get over it. In the long run, it is the easy way.

Communication
Keep the lines of communication open. Network with people who may be valuable to you when you’re trying to troubleshoot a system. Keep those who have an interest in the system well informed of problems you discover or changes you make to the system.

It Is Not Necessarily About Knowing One PLC Or Another – It Is About Understanding The Troubleshooting Method
All PLCs are different. All systems are different. The real key to being a good troubleshooter is to understand the Troubleshooting Method.

First, try to understand how to troubleshoot anything and let your method be refined as you gain experience.

DO NOT Compromise The Safety Of A Machine By Altering The Program
Before you make any changes to the program, always ask yourself if this change will affect the safety of the machine or the people who work around it.

No One Expects You To Wave A Magic Wand
No one expects you to wave a magic wand and get the machine to work. What is expected, however, is that you have a goal and a plan, and that you are executing the plan. It is true that, many times, there is pressure in a troubleshooting scenario.

Don’t be nervous; present a blend of humility and confidence. In other words, respect what information is given to you, but be prepared to make your own decisions regarding how to proceed with the troubleshooting.

Know When To Stop
Don’t go past the mark you aimed for; know when to stop.

That moment of victory is often the moment of greatest peril. When you have solved the initial problem, and you are the hero, arrogance and overconfidence can push you past the goal you had aimed for. By going too far, you make new problems for yourself.  Don’t allow success to go to your head.  Remember that there is no substitute for strategy and careful planning. Set a goal, and when you reach it, stop.

It seems that high prices for gasoline and heating oil used in homes are here to stay. Sure, they go up and down, but overall they still remain pretty high and consume more of our pocketbooks than they ever have in the past. We are constantly struggling with the Middle East, at least in part to protect our interest in their oil. And as other nations, including China and India, increase their demand for fossil fuels, it seems that conflicts regarding energy are looming large on the horizon. In the meantime, power plants that burn fossil fuels, as well as all of our vehicles everywhere, continue to pour millions of tons of pollutants into the atmosphere annually, threatening our health and well-being.

There are a number of well-meaning scientists, engineers and politicians who have presented various methods that could slightly reduce our use of fossil fuel. However, these steps are not enough. The US needs a plan to work itself away from our dependence on fossil fuels. It appears that only answer is a transition to solar power.

The potential of solar energy is overwhelming. For example, the energy in the sunlight striking the earth for only 40 minutes is equivalent to our human global energy consumption for one year. The U.S. is lucky in the sense that we have at least 250,000 mi. of land in the Southwest alone that is suitable for building solar power plants. That land receives more than 4500 quadrillion British thermal units (BTUs) of solar radiation every year. If we were to convert only 2.5% of that radiation into electricity, we would match the nation’s total energy consumption of 2006.

However, to convert this solar power, large tracts of land would have to be covered with photovoltaic cells and perhaps solar heating troughs.

The good news is that the technology is nearly ready. Let’s look at photovoltaic farms.

In the last few years, the cost to produce photovoltaic cells and modules have really dropped pretty radically, opening the way for large-scale implementation. A number of cell types exist, but the best modules today are made of very thin films of cadmium telluride. To work up the numbers, if we were to provide electricity at $.06 per kilowatt-hour by the year 2020, cadmium telluride modules must be able to convert electricity with at least 14% efficiency and complete systems would have to be installed at about a $1.20 per watt capacity. Current modules have only 10% efficiency and an installed system costs about $4 per watt. We are making progress, and the technology is advancing rapidly; commercial efficiencies have risen to upwards of 10% in the last year. As these commercial efficiencies rise, rooftop photovoltaic for the home will become even more cost competitive, further reducing daytime electricity demand on the utilities.

In one scenario, by 2050, photovoltaic technology could provide almost 3000 GW, or billions of Watts, of power. 30,000 square miles of photovoltaic arrays would need to be constructed. This may seem like a huge number, but current installations already in place show that the land required for each gigawatt hour of solar energy produced in the Southwest is less than the actual amount needed for a power plant when the area used for coal mining is taken into consideration. The National Renewable Energy Laboratory in Golden, Colorado shows that more than enough land in the Southwest is available without disturbing any environmentally sensitive areas, cities or towns. In Arizona, the Department of Water Conservation has stated that more than 80% of the state’s land is not privately owned and that Arizona is very interested in developing its solar potential. Because of the nature of photovoltaic plants, and the lack of water required to operate these plants, the environmental impact should be minimal.

The main problem is still reaching that magic number of module efficiency of 14%. Although the efficiencies of commercial modules won’t reach those of solar cells in the laboratory, cadmium telluride cells at the National Renewable Energy Laboratory are now up to 16.5% and rising. At least one manufacturer, First Solar in Perrysburg, Ohio, has increased the efficiency of their modules from 6% to 10% from 2005-2007. They plan on reaching 11.5% by 2010.

So, the trick is to keep an eye on the efficiencies of solar cells. After they reach 14% efficiency and the base cost per kilowatt hour becomes more acceptable, expect to see a number of companies and individuals making investments in this future.

1 a logic positive, high, or 1.

A/D Analog to digital converter (see ADC).

abort the disruption of normal operation.

absolute pressure a pressure measured relative to zero pressure.

absorptive law a special case of Boolean algebra where A(A+B) becomes A.

absorption loss
when sound or vibration energy is lost in a transmitting or reflecting medium. This is the result of generation of other forms of energy such as heat.

AC (Alternating Current)
most commonly an electrical current and voltage that changes in a sinusoidal pattern as a function of time. It is also used for voltages and currents that are not steady (DC). Electrical power is normally distributed at 60Hz or 50Hz.

AC contactor
a contactor designed for AC power.

acceptance test
a test for evaluating a newly purchased system’s performance, capabilities, and conformity to specifications, before accepting, and paying the supplier.

accumulator
a temporary data register in a computer CPU.

accuracy
the difference between an ideal value and a physically realizable value.

acidity
a solution that has an excessive number of hydrogen atoms. Acids are normally corrosive.

acknowledgement (ACK)
a response that indicates that data has been transmitted correctly.

acoustic
another term for sound.

actuator
a device that when activated will result in a mechanical motion. For example a motor, a solenoid valve, etc.

ADC (Analog to Digital Converter)
a circuit that will convert an analog voltage to a digital value, also referred to as A/D.

ADCCP (Advanced Data Communications Procedure)
ANSI standard for synchronous communication links with primary and secondary functions.

address
a code (often a number) that specifies a location in a computers memory.

address register
a pointer to memory locations.

adsorption
the ability of a material or apparatus to adsorb energy.

agitator
causes fluids or gases to mix.

AI (Artificial Intelligence)
the use of computer software to mimic some of the cognitive human processes.

algorithms
a software procedure to solve a particular problem.

aliasing
in digital systems there are natural limits to resolution and time that can be exceeded, thus aliasing the data. For example. an event may happen too fast to be noticed, or a point may be too small to be displayed on a monitor.

alkaline
a solution that has an excess of HO pairs will be a base. This is the compliment to an acid.

alpha rays
ions that are emitted as the result of atomic fission or fusion.

alphanumeric
a sequence of characters that contains both numbers and letters.

ALU (Arithmetic Logic Unit)
a part of a computer that is dedicated to mathematical operations.

AM (Amplitude Modulation)
a fixed frequency carrier signal that is changed in amplitude to encode a change in a signal.

ambient
normal or current environmental conditions.

ambient noise
a sort of background noise that is difficult to isolate, and tends to be present throughout the volume of interest.

ambient temperature
the normal temperature of the design environment.

analog signal
a signal that has continuous values, typically voltage.

analysis
the process of review to measure some quality.

and
a Boolean operation that requires all arguments to be true before the result is true.

annealing
heating of metal to relieve internal stresses. In many cases this may soften the material.

annotation
a special note added to a design for explanatory purposes.

ANSI (American National Standards Institute)
a developer of standards, and a member of ISO.

APF (All Plastic Fiber cable)
fiber optic cable that is made of plastic, instead of glass.

API (Application Program Interface)
a set of functions, and procedures that describes how a program will use another service/library/program/etc.

application
the task which a tool is put to, This normally suggests some level of user or real world interaction.

application layer
the top layer in the OSI model that includes programs the user would run, such as a mail reader.

APT (Automatically Programmed Tools)
a language used for directing computer controlled machine tools.

arc
when the electric field strength exceeds the dielectric breakdown voltage, electrons will flow.

architecture
the general layout or design at a higher level.

armature
the central rotating portion of a DC motor or generator, or a moving part of a relay.

ARPA (Advanced Research Projects Agency)
now DARPA. Originally funded ARPANET.

ASCII (American Standard Code for Information Interchange)
a set of numerical codes that correspond to numbers, letters, special characters, and control codes.

aspirator
a device that moves materials with suction.

assembler
converts assembly language into machine code.

assembly language
a mnemonic set of commands that can be directly converted into commands for a CPU.

associative dimensioning
a method for linking dimension elements to elements in a drawing.

associative laws
Boolean algebra laws A+(B+C) = (A+B)+C or A(BC) = (AB)C

asynchronous
events that happen on an irregular basis, and are not predictable.

asynchronous communications (serial)
strings of characters (often ASCII) are broken down into a series of on/off bits. These are framed with start/stop bits, and parity checks for error detection, and then send out one character at a time. The use of start bits allows the characters to be sent out at irregular times.

attenuation
to decrease the magnitude of a signal.

attenuation
as the sound/vibration energy propagates, it will undergo losses. The losses are known as attenuation, and are often measured in dB. For general specifications, the attenuation may be tied to units of dB/ft.

attribute
a nongraphical feature of a part, such as color.

audible range
the range of frequencies that the human ear can normally detect from 16 to 20,000 Hz.

automated
a process that operates without human intervention.

automatic control
a feedback of a system state is compared to a desired value and the control value for the system is adjusted by electronics, mechanics and/or computer to compensate for differences.

auxiliary power
secondary power supplies for remote or isolated systems.

AWG (American Wire Gauge)
specifies conductor size. As the number gets larger, the conductors get smaller.