Comparative Evaluation of HVAC and HVDC

1.   Introduction

The transmission and distribution of electrical energy

started with direct current (DC) in the late 19th century, but

it was inefficient due to the power loss in conductors.

Alternating current (AC) offered much better efficiency,

since it could easily be transformed to higher voltages, with

far less loss of power. AC technology was soon accepted as

the only feasible technology for generation, transmission

and distribution of electrical energy.

However, high-voltage AC transmission links have

disadvantages and engineers were engaged in the

development of a technology for DC transmissions as a

supplement to the AC transmissions. The invention of

mercury arc rectifiers and the thyristor valves, made the

design and development of line-commutated current

sourced converters possible.

High Voltage Direct Current (HVDC) transmission finally

proved to be technically feasible. The world's first

commercial HVDC transmission link, was built in 1954

between the Swedish mainland and the island of Gotland,

with a rating of 20 MW, 200 A and 100 kV

Questions About Electric Power Transmission

Transmission of electrical power is commonly performed on high voltage, either using the HVAC (high voltage alternating current) and HVDC (high voltage direct current). the former uses an alternating current and this is contained in our country. The second course uses direct current. in this post, I will not touch such a question: Which is better, HVAC or HVDC? My problem is something more fundamental, namely concerning the reasons why the transmission done at a high voltage (even extra high) . it was clear from some college (khususnya high voltage engineering) that the transmission of electrical power carried on the high voltage to reduce losses associated with the transmission line impedance. but ... .Please refer to here to find out more about the various voltage values commonly used in transmission lines and its classification.

HVDC

Use of High Voltage Direct Current Transmission (HVDC) or in Indonesian terms is known as direct current power transmission (TDAS) actually started in the beginning of the first electricity was developed. Thomas Alva Edison made electricity network with a capacity of 6 x 100kW to power in 1200 using direct current light bulb in 1882. Although in its development, Edison developed dc system was 'lost' to compete with the ac system proposed by Westinghouse and Tesla, but these systems have been dc new era, the era of electricity. More than 70 years later, the dc transmission system came into use again after finding a mercury-arc tube at the end of the 1920s. Commercial HVDC project was first built in 1950 using a submarine cable to link Sweden with P. Gotland with a capacity of 20MW at 100kV voltage.
This paper briefly describes the technology, configuration, and application of direct current power transmission (HVDC).
HVDC technology started to be used again because the tube / mercury-arc already well established so that power converter ac / dc or dc / ac can be made, something that can not be done in the 1880s that resulted in the defeat of Edison's direct current alternating current system Westinghouse behind. Mercury-arc tube technology itself only lasted about 20 years until the invention of the thyristor at around 1970. This thyristor is the basis of the rapid development of HVDC technology because it can be made for the purposes of power, compared to the transistor / IGBT that with today's technology has a smaller capacity than the thyristor. The last decade, the development of IGBT technology allows for the HVDC converter is made by using IGBT (Figure 1), although its capacity is smaller than HVDC systems using thyristor converters. 

    Figure 1. Development of a static switch for HVDC

Electrolytes

Electrolytes

Electrolytes are substances that form solutions that conduct electricity. Pure water does not conduct electricity. Water molecules do not dissociate significantly to form charge carriers (ions).

Electrolytes dissolve in water or some other solvent and form ions. Sodium chloride is an electrolyte. When NaCl dissolves in water the crystal is separated into Na1+ and Cl1- ions. The ions are surrounded by solvent molecules. The clumps of solvent molecules and ions are mobile in the solution. The clumps are centerd on the charged ions and are able to carry electrical charge through the liquid.

Strong electrolytes are substances that convert completely to ions when they dissolve. They are also said to be 100% ionized. The solubility of ionic compounds limits their ability to conduct.

What Ultrasonic Flowmeters

Ultrasonic flowmeters are very promising instruments for pipe flow measurement in process control, flow survey, custody transfer etc. They have many advantages over conventional flowmeters as will be explained later. In the following we are going to focus on how to select the right ultrasonic flowmeter for liquid applications

Liquid ultrasonic flowmeters can be classified in many ways:

(1) Based-on principle: Transit-time vs. Doppler

Distance Relay

Distance or distance relays are used as a safety relay main (main protection) in a transmission system, whether or SUTET SUTT, and as a backup or a backup for the front section. Distance relay works by measuring the amount of impedance (Z), and transmission is divided into several areas of security coverage of Zone-1, Zone-2, and Zone-3, and equipped also with teleproteksi (TP) in a bid for protection work is always fast and selective inside the security area. etc..

Working Principle Distance Relay Relay distance relays measure voltage and current at the point of visible disruption of the relay, by dividing the amount of voltage and current, the impedance to the point of interference can be determined. The calculation of the impedance can be calculated using the following formula:

Humidity Sensors (CMOS)

Humidity sensors are gaining more significance in diverse
areas of measurement and control technology. Manufacturers
are not only improving the accuracy and long-term drift of
their sensors, they are improving their durability for use in
different environments, and simultaneously reducing the
component size and the price.

CMOS Humadity Sensor

Gas Insulated Switchgear (GIS)

Since gas insulated transformers do not require a conservator, the height of the transformer room can be reduced. In addition, the characteristics of non-flammability and reduced risk of tank explosion mean fire-fighting equipment can be removed from the transformer room.

As a result, the gas insulated transformer, gas insulated shunt reactor, GIS and control panels can be all housed in one room.

 Layout Example of 300kV Insulated Substation

Electrical Flashover

Mike Frain looks at the dangers of live testing and fault finding in industrial and commercial low voltage electrical installations.

In advising industrial and commercial companies on electrical safety rules and procedures, I make enquiries to every delegate on training courses about their own experiences. A good percentage have said that they have experienced electrical flashover (arc flash) and I have yet to meet anybody who has never received an electric shock. Most of us know it takes a very small amount of current flow through the body to cause death. Where death has not occurred this is due simply to the fortuitous nature of the current path in missing vital organs. What is required therefore to survive an electric shock from mains voltage is luck!

Power Electronic Textiles

The clothing of the future could be more than just fashion. MIT researchers are working to develop fibers that can hear and produce sound, and someday those could take the form of wearable electronics.
“The ancients used clothes for the same reason that we do, which is thermal insulation and aesthetics,” Yoel Fink, associate professor of materials science and principal investigator at MIT’s Research Lab of Electronics, told Wired.com. “What we have done is start thinking how fibers go beyond that and change their properties.”

New Power Amplifier Driving Piezoelectric Transducers

Midé Technology’s QPA202 is a single-channel, linear power amplifier specifically designed for driving Midé’s line of Quickpack / PowerAct transducers and other high-voltage piezoelectric capacitive transducers. The QPA202 is an improved version of the QPA200, with an extended bandwidth (8kHz) and output current increased to 2 Amperes (2A). It offers a fixed or adjustable DC gain up to 50 V/V with a bipolar output range from +200V to –200V. 

Piezos need to be driven by an amplifier to be effectively used in a myriad of ways. They can be used in laser mirror alignment, or to reduce vibrations in a structure. They can be used to acoustically cancel noise, or to replace solenoid valves in controlling the flow of fluids or gases. Piezos can be driven to move air, or to stir fluids for medical or manufacturing processes. The recently released QPA202 QuickPack Piezo Power Amplifier is able to drive these piezoelectric dependant technologies even further.

Difference Between Gauge and Absolute Pressure Measurement

Determining whether you need gauge or absolute reference pressure is as important as selecting the pressure range itself, particularly for low pressure measurements. If you get it wrong your measurements are going to be out by approximately 1 bar, which could be a huge error if you have specified a 10 bar range for example. 

Also if you have taken delivery of a pressure transducer with the wrong pressure reference it will normally mean that the manufacturer will have to build a replacement because the reference pressure often determines the base construction of the sensing element.

Ultrasound Transducer

In ultrasound, the following events happen:

1. The ultrasound machine transmits high-frequency (1 to 5 megahertz) sound pulses into your body using a probe.
2. The sound waves travel into your body and hit a boundary between tissues (e.g. between fluid and soft tissue, soft tissue and bone).
3. Some of the sound waves get reflected back to the probe, while some travel on further until they reach another boundary and get reflected.
4. The reflected waves are picked up by the probe and relayed to the machine.
5. The machine calculates the distance from the probe to the tissue or organ (boundaries) using the speed of sound in tissue (5,005 ft/s or1,540 m/s) and the time of the each echo's return (usually on the order of millionths of a second).
6. The machine displays the distances and intensities of the echoes on the screen, forming a two dimensional image like the one shown below.

AVR Microcontroller Featuring Floating Point Unit The First 32-bit

The IEEE 754-1985-compatible FPU increases the performance, precision and dynamic range of calculations offered by the Atmel AVR UC3 CPU. The native support for the floating point arithmetic allows design engineers to use a full-featured toolbox for designing sensor and control applications. In addition, the advanced math can be applied to enhance signal processing, filtering, and noise suppression in a wide range of applications including motor control, robotics and audio.

Calibration Management Software

ProCalV5 Professional is a comprehensive system designed to assist calibration and quality managers maintain compliance. It eliminates the need for calculators when creating records, during the calibration process or when approving final records. A library of routines for forced e-signature routings can be created and individually attached to any device or activity. Global changes, automatic archiving, paperless import/export of work assignments and much more are just some of the features within this robust system. 

Intuitive User Interface
The user interface of ProCalV5 allows you to open and run multiple screens at the same time. No matter how many screens are open, you are just a mouse click away from any place you want to be.

Electricity From Gas And Water (Fluid Transducer)

A large number of technical systems work with air or water. Air compression systems and water pipes are just two examples. Researchers of the Fraunhofer Technology Development Group TEG have now successfully managed to convert this fluidic energy into electricity. This could enable sensors to supply themselves with energy in future.

Activities of Smart Grid

Standardized architectural designs and interfaces are important to stimulate developments toward a smart grid. OE has supported development and testing of the IEEE 1547 Series of Standards on interconnecting distributed resources with electric power systems by the National Renewable Energy Laboratory. In addition, OE has supported the Pacific Northwest National Laboratory and the GridWise Architecture Council to identify areas for standardization to allow significant levels of interoperation among electric grid system components. Furthermore, OE also supports public/private partnerships such as the GridWise Alliance and the Grid Modernization Collaborative to coordinate and collaborate on smart grid development.
These and other OE R&D activities, organized below under four key Technology Areas, will directly contribute to achieving the performance features of a smart grid:

Architecture & Communication StandardsArchitectural framework and components to enable interoperability of all components and systems in the nation's power grid including existing legacy systems.

SMART GRID Technology

Smart grid technology and the future of our aging electrical grid system is big talk around the white house and congress these days. Our president Barack Obama says we must increase the development of solar and wind power. We must get people to use less energy and we must work on the global warming and climate change issue.
So what is smart grid technology? It is basically the electrical system moving into the digital age. What they are looking at are home thermostats and appliances that will adjust themselves for the cost of power. Water heaters that can draw power from a neighbor's rooftop solar panel. Cars that will run on electricity and can be charged in one minute.

Camcorder Image Sensors

The image sensor in a camcorder (or digital camera) is what puts the "digital" into a digital camcorder. Put simply, an image sensor transforms the light captured by your camcorder's lens and turns it into a digital signal. That digitized light gets processed and stored in your camcorder's memory as a digital video file which you can later view on your computer or TV. Next to the lens itself, the image sensor is the essential element that ensures quality video.
There are two main types of camcorder image sensors: CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor). Both types of image sensor technology contain hundreds of thousands or even millions of pixels. Think of a pixel as a tiny bucket that captures light and turns it into an electrical signal.

About Solar Energy

What is a solar cell and a solar module?
A solar cell, also called a photovoltaic (PV) cell, is the smallest element that converts light into electrical energy. Each cell is made of silicon like a computer chip. The silicon is treated so that it generates a flow of electricity when light shines on it. Solar modules are series of solar cells wired together.

Safety Interlock Switches

Safety interlock switches are specialized or proprietary products and accessories related to safety sensors and switches. There are several types of specialty safety switches. Examples include interlock safety systems, safety key switches, and non-contact interlock safety switches. An interlock safety system is a strong control system that provides protection to personnel, equipments and plants. Safety key switches are another type of specialty safety switch that uses a key as activation source. A non-contact interlock safety switch is used to detect the opening of guards-including doors, gates and/or removable covers-that prevent access to dangerous parts of a machine, and to help deter tampering with the guards or the internal machine controls. Other specialty safety switches are commonly available.

Specialty safety switches function in a variety of ways. Safety sensors are connected to equipment and machineries in industries and detect unsafe conditions. A specialty safety switch is an open and close circuit which can be operated manually using operating mechanisms or they can also operate automatically with the help of a fuse.

safety interlock switches

Safety Sensors

Safety sensors are used to detect unsafe conditions and transmit signals to devices that alert personnel such as machine operators. Safety sensors attach to many different types of machinery and equipment. Safety sensing devices and safety sensing systems often interface to a computer or programmable logic controller (PLC). They are well-suited for applications and industries that require safety material presence sensing. The most common types of safety sensors are break-a-beam switches, interlocks and tag out devices, perimeter guards, photoelectric safety sensors, safety blocks, safety interlock switches, safety sensor switches, and wireless safety sensors. Many safety sensor suppliers are located across the United States and around the world.

Safety sensors, safety sensing devices, and safety sensing systems use many different technologies. A break-a-beam sensor transmits a signal when a beam of light is interrupted. An interlock or tag out device prevents valves or electrical switches from working when a safety condition is breached.

Safety Sensors

Safety Standards (IEC )

IEC 61511

This international standard gives reqirements for the specification,  design, installation, operation and maintenance of a safety instrumented system, so that it can be confidently entrusted to place and/or maintain the processin a safe state.

Relationship between IEC 61511 and IEC 61508

SIS ( Safety Instrumented Systems )

A Safety Instrumented System SIS is a new term used in standards like IEC 61511 or IEC 61508 for what used to be called Emergency Shutdown System ESD, Safety Shutdown System, Interlock System, Permissive Systems, etc. ...

A Safety Instrumented System SIS consists of one or more Safety Instrumented Functions SIF.

Safety Instrumented System