Infographic: Understanding the Impact of Power Quality

Courtesy : schneider

Researchers develop new method to remove dust on solar panels

Taking a cue from the self-cleaning properties of the lotus leaf, researchers at Ben-Gurion University of the Negev have shed new light on microscopic forces and mechanisms that can be optimized to remove dust from solar panels to maintain efficiency and light absorption. The new technique removed 98 percent of dust particles.

In a new study published in Langmuir, the researchers confirmed that modifying the surface properties of solar panels may greatly reduce the amount of dust remaining on the surface, and significantly increase the potential of solar energy harvesting applications in the desert.

Dust adhesion on solar panels is a major challenge to energy harvesting through photovoltaic cells and solar thermal collectors. New solutions are necessary to maintain maximum collection efficiency in high dust density areas such as the Negev desert in Israel.

"In nature, we observe that the lotus leaf remains dust and pathogen free due to its nanotextured surface, and a thin wax, hydrophobic coating that repels water," says Tabea Heckenthaler, a master's student from Düsseldorf Germany at the BGU Zuckerberg Institute for Water Research, Jacob Blaustein Institutes for Desert Research. "In the desert, dust accumulates on the surface of solar cells and it's labor-intensive to clean them constantly, so we're trying to mimic this behavior on a solar cell."

The researchers explored the effect of modifying a silicon substrate (Si), a semiconductor used in photovoltaic cells, to mimic the self-cleaning properties of the lotus leaf, as water rolls down the leaves and removes contamination.

It is known that superhydrophobicity reduces the friction between water droplets and the surface, thus allowing water drops to slide clean particles from surfaces. However, the forces that attach and detach particles from surfaces during the self-cleaning mechanism and the effect of nano textures on these forces are not fully understood.

To shed light on these forces and the effect of nanotexture on them, the researchers prepared four silicon-based samples relevant to solar panels: (1) smooth hydrophilic (2) nanotextured hydrophilic surfaces and (3) smooth hydrophobic (4) nanotextured hydrophobic surfaces. This was achieved by wet-chemically etching the surface to create nanowires on the surface, and additionally applying a hydrophobic coating.

Particle removal increased from 41 percent on hydrophilic smooth Si wafers to 98 percent on superhydrophobic Si-based nanotextured surfaces. The researchers confirmed these results by measuring the adhesion of a micron-sized particle to the flat and nanotextured substrate using an atomic force microscope. They found that the adhesion in water is reduced by a factor of 30.

"We determined that the reason for the increased particle removal is not low friction between the droplets and the superhydrophobic surfaces," Heckenthaler says. "Rather, it is the increase in the forces that can detach particles from the surfaces. The experimental methods we used and the criterion for particle removal we derived can be implemented to engineer self-cleaning surfaces exhibiting different chemistries and/or textures."

Emerich_Invitation to CII Energy Efficiency Summit 2019

NEWS : Ambassador To Return As PSA's EV Brand For India

The French auto giant PSA Peugeot Citroen had acquired Ambassador from Hindustan Motors in 2017. It will now be resurrected as an electric vehicle or EV-only brand specifically for India. The first car is expected to hit the market in late 2022.

While the PSA Peugeot-Citroen group has officially announced that it will bring its Citroen brand to India, we finally have some news on its plans for Ambassador too. Two days before holding its first-ever official press conference in India to show us Citroen's debut model for the country (that will launch in 2021), carandbike has learnt of a parallel plan afoot within the company. Speaking on specific conditions of anonymity, senior PSA board member and reclusive heiress Evié de Courant has shared with this reporter that the Ambassador brand will be used exclusively for electric vehicles to be sold in India only. The sub-brand will be the first new addition to the PSA family, after its last acquisition of erstwhile GM brands Opel and Vauxhall in August 2017.

The Ambassador range of cars will likely only debut post 2022, and it is not as yet decided whether it would entail a standalone retail network. While Citroen will have a full-fledged dealer network, Ambassador branded cars are likely to be sold using an exclusive online sales strategy. Workshops for the two will be common though. The plan is to initially launch a compact SUV or crossover style car, and then a premium hatchback. Both are expected to share their platform and some components with similar sized ICE (internal combustion engine) models from the Citroen brand, to maximise economies of scale. The intent is to make Ambassador a profit-making entity from within the first quarter of the start of sales.

Source:Online News 

NEWS: Jaguar Land Rover to launch multiple electric cars in India, starting 2019

Latest News: Tata Motors owned Jaguar Land Rover (JLR) 

In line with Jaguar Land Rover's global commitment to introduce electrified options on its entire product portfolio by 2020, Jaguar Land Rover India proposes to offer multiple products, ranging from Hybrid Vehicles to Battery Electric Vehicles (BEV) over the next few years, starting from 2019.

Luxury car makers in India are all set to bring in hybrid electric and pure electric cars to India. Audi has already announced that the e-tron will make its debut in the country in 2020, while Porsche too is bringing in the Taycan next year. Volvo has already announced its roadmap for the country and Mercedes-Benz India is still doing feasibility studies to introduce electric cars in India and now Jaguar Land Rover is jumping into this scene. Jaguar Land Rover is proposing to launch its electrified products in India.

Why Earthing is Required & Earthing Components

Earthing is the method of transmitting the instant electricity discharge directly to the ground through low resistance wires or electrical cables. This is one of the significant features of electrical networks. Because it builds the most eagerly accessible and hazardous power source much secure to utilize.

The process of earthing in case of short circuit condition, the electrical wire carefully removes the overflow of current and allows it to flow through the earth. All this occurs without unnecessary problems, only through resourceful and inexpensive manufacture, plan as well as arrangement!

Why Earthing is Required?

The main intention of electrical earthing is to keep away from the danger of electric shock due to the outflow of current from ground through the not preferred path as well as to make sure that the potential of a conductor does not increase with respect to the ground than its planned insulation.

When the metallic element of electrical machines approaches in contact by an existing wire, due to a breakdown of fixing the cable, the metal turn into charged and static charge collect on it. If someone contacts such an electric metal, then the outcome is a severe electric shock. 

So finally We can conclude that life is random, and one should always get ready for unexpected circumstances. So buildings and electric appliances have to be grounded to transfer the electric charge directly to the ground. The main benefits of grounding include protection from over voltage, stabilization of voltage, and prevention form injury, damage, and death.

Components used in Electrical Earthing System

The main components used in earthing system mainly include earth cable, earthing joint (earthing lead), and earth plate

Earth Cable

The conductor is used to connect metallic parts of an electrical system like plug sockets, metallic shells, fuses, distribution boxes. Metallic parts of motors, transformers, generators, etc. the range of these conductors depend on the earth cable size used in the wiring circuit. The earth wire in the cross-sectional area must be less than the solid wire used in the electrical wiring system.

In general, the copper wire utilized as an earth continuity conductor size is 3-standard wire gauge (SWG). Ground wires which are smaller than 14-SWG should not be used. In some situations, copper strips are used instead of a bare copper conductor.

Earthing Joint

The ‘ground electrode’ as well as conductors fixing to the ‘ground continuity conductor’ is called earthing joint (earthing lead).  The tip where the earthing joint connects the ground continuity conductor is known as connecting end. The lead of the ground must be low size, straight, & should include a minimum amount of joints. Although copper wires are usually used as grounding leads; whereas copper strips are selected for high fitting because it carries high fault current values due to its broad region.

Earth Plate

The last part of the electrical grounding system which is hidden underground and linked to the lead of grounding is known as the earth plate. Earth electrode is a pipe, plate or metallic rod, or plate; which has extremely low resistance for carrying the fault current to the ground safely.

It can be of iron or copper rod and must be placed in wet earth and in case the moisture content of earth is low then put some water in the earth plate. The earth plate is always placed in the vertical, and coat with salt and charcoal lime around the earth plate. This helps in protecting the earth plate as well as in maintains ground moisture around the earth plate. The earth plate must be placed four meters long for the better earthing.

Types of Electrical Earthing Systems

The process of Earthing or electrical grounding can be done in several ways like wiring in factories, housing, other machines, and electrical equipment. The different types of electrical earthing systems include the following.

Plate Earthing System

In this type of system, a plate is made up of copper or GI (galvanized iron) which are placed vertically in the ground pit less than 3 meters from the earth. For a better electrical grounding system, one should maintain the earth moisture condition around the plate earthing system.

Pipe Earthing System

A galvanized steel based pipe is placed vertically in a wet is known as pipe earthing, and it is the most common type of earthing system. The pipe size mainly depends on the soil type and magnitude of current. Usually, for the ordinary soil, the pipe dimension should be 1.5 inches in diameter and 9 feets in length. For rocky or dry soil, the pipe diameter should be greater than the ordinary soil pipe. The soil moisture will decide the pipe’s length to be placed in the earth. The pipe earthing diagram is shown below:

Rod Earthing System

This type of earthing system is similar to pipe earthing system. A copper rod with galvanized steel pipe is placed upright in the ground physically or using a hammer. The embedded electrodes lengths in the earth decrease the resistance of earth to a preferred value.

This is all about what is meant by earthing / definition of earthing and its types. From the above information, finally, we can conclude that the earthing system or electrical grounding system offers greater safety from electric shock for personal, equipment, buildings, etc. The ground sensitivity can be The earth resistivity can be affected by some issues like soil and climate, a condition of resistivity, moisture, melted salts, earth pit location, physical work, grain size effect, current magnitude, etc. 

ABT Meter Functions & Its Mechanism!

The ABT Energy Meters are specifically designed Three Phase, Four Wire static meters having accuracy class of 0.2S. Function of ABT meters is to measure the net energy transmitted in Wh in each 15-minute time block of real time along with the average frequency. This meters are designed to record reactive energy in VARh under the predefined high /low voltage condition.  

How does the mechanism work   

The process starts with the Central generating stations in the region declaring their expected output capability for the next day to the Regional Load Dispatch Centre (RLDC). The RLDC breaks up and tabulates these output capability declarations as per the beneficiaries' plant-wise shares and conveys their entitlements to State Load Dispatch Centres (SLDCs). The latter then carry out an exercise to see how best they can meet the load of their consumers over the day, from their own generating stations, along with their entitlement in the Central stations. They also take into account the irrigation release requirements and load curtailment etc. that they propose in their respective areas. The SLDCs then convey to the RLDC their schedule of power drawal from the Central stations (limited to their entitlement for the day). The RLDC aggregates these requisitions and determines the dispatch schedules for the Central generating stations and the drawal schedules for the beneficiaries duly incorporating any bilateral agreements and adjusting for transmission losses. These schedules are then issued by the RLDC to all concerned and become the operational as well as commercial datum. However, in case of contingencies, Central stations can prospectively revise the output capability declaration, beneficiaries can prospectively revise requisitions, and the schedules are correspondingly revised by RLDC.

     While the schedules so finalized become the operational datum, and the regional constituents are expected to regulate their generation and consumer load in a way that the actual generation and drawls generally follow these schedules, deviations are allowed as long as they do not endanger the system security. The schedules are also used for determination of the amounts payable as energy charges, as described earlier. Deviations from schedules are determined in 15-minute time blocks through special metering, and these deviations are priced depending on frequency. As long as the actual generation/drawal is equal to the given schedule, payment on account of the third component of Availability Tariff is zero. In case of under-drawal, a beneficiary is paid back to that extent according to the frequency dependent rate specified for deviations from schedule.  

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Why Availability Tariff is necessary ? & Its Benefits

The regional grids had been operating in a very undisciplined and haphazard manner. There were large deviations in frequency from the rated frequency of 50.0 cycles per second (Hz). Low frequency situations result when the total generation available in the grid is less than the total consumer load. These can be curtailed by enhancing generation and/or curtailing consumer load. High frequency is a result of insufficient backing down of generation when the total consumer load has fallen during off-peak hours. The earlier tariff mechanisms did not provide any incentive for either backing down generation during off-peak hours or for reducing consumer load / enhancing generation during peak-load hours. In fact, it was profitable to go on generating at a high level even when the consumer demand had come down. In other words, the earlier tariff mechanisms encouraged grid indiscipline.

The Availability Tariff directly addresses these issues. Firstly, by giving incentives for enhancing output capability of power plants, it enables more consumer load to be met during peak load hours. Secondly, backing down during off-peak hours no longer results in financial loss to generating stations, and the earlier incentive for not backing down is neutralized. Thirdly, the shares of beneficiaries in the Central generating stations acquire a meaning, which was previously missing. The beneficiaries now have well-defined entitlements, and are able to draw power up to the specified limits at normal rates of the respective power plants. In case of over-drawal, they have to pay at a higher rate during peak load hours, which discourages them from over-drawing further. This payment then goes to beneficiaries who received less energy than was scheduled, and acts as an incentive/compensation for them.

How does it benefit everyone 

The mechanism has dramatically streamlined the operation of regional grids in India. Firstly, through the system and procedure in place, constituents’ schedules get determined as per their shares in Central stations, and they clearly know the implications of deviating from these schedules. Any constituent which helps others by under-drawal from the regional grid in a deficit situation, gets compensated at a good price for the quantum of energy under-drawn. Secondly, the grid parameters, i.e., frequency and voltage, have improved, and equipment damage correspondingly reduced. During peak load hours, the frequency can be improved only by reducing drawls, and necessary incentives are provided in the mechanism for the same. High frequency situation on the other hand, is being checked by encouraging reduction in generation during off-peak hours. Thirdly, because of clear separation between fixed and variable charges, generation according to merit-order is encouraged and pithead stations do not have to back down normally. The overall generation cost accordingly comes down. Fourthly, a mechanism is established for harnessing captive and co-generation and for bilateral trading between the constituents. Lastly, Availability Tariff, by rewarding plant availability, enables more consumer load to be catered at any point of time.

How do the beneficiaries share the payments  

The Central generating stations in different regions of the country have various States of the Region as their specified beneficiaries or bulk consumers. The latter have shares in these plants calculated according to Gadgil formula, and duly notified by the Ministry of Power. The beneficiaries have to pay the capacity charge for these plants in proportion to their share in the respective plants. This payment is dependent on the declared output capability of the plant for the day and the beneficiary's percentage share in that plant, and not on power / energy intended to be drawn or actually drawn by the beneficiary from the Central station.

The energy charge to be paid by a beneficiary to a Central station for a particular day would be the fuel cost for the energy scheduled to be supplied from the power plant to the beneficiary during the day. In addition, if a beneficiary draws more power from the regional grid than what is totally scheduled to be supplied to him from the various Central generating stations at a particular time, he has to pay for the excess drawal at a rate dependent on the system conditions, the rate being lower if the frequency is high, and being higher if the frequency is low.

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Overview of Availability Based Tariff (ABT) Meters

Availability Based Tariff (ABT) is a frequency based pricing mechanism applicable in India for unscheduled electric power transactions.

ABT Mechanism in Electricity sector in India is adopted since the year 2000 and in a few other countries for pricing bulk power across various stakeholders. ABT concerns itself with the tariff structure for bulk power and is aimed at bringing about more responsibility and accountability in power generation and consumption through a scheme of incentives and disincentives. As per the notification, ABT was initially made applicable to only central generating stations having more than one SEB/State/Union Territory as its beneficiary. Through this scheme, the Central Electricity Regulatory Commission (CERC) looks forward to improve the quality of power and curtail the following disruptive trends in power sector:

Unacceptably rapid and high frequency deviations (from 50 Hz) causing damage and disruption to large scale industrial consumers Frequent grid disturbances resulting in generators tripping, power outages and power grid disintegration.

The ABT scheme has now been expanded to cover the Intrastate systems as well. The power generation or grid capacity has increased substantially in last fifteen years particularly after the Electricity Act 2003 by introduction of competition and un-bundling of vertically integrated utilities (SEBs) into separate entities in charge of electricity generation, electricity transmission, and electricity distribution. Deregulation and competition has facilitated participation of private sector on large scale in electricity generation, transmission and distribution. Of late, Indian electricity sector is transforming from perennial deficit to surplus electricity availability. The volume of purchased electricity that could not be transmitted to the buyers due to transmission lines congestion is only 0.3% of the total electricity consumed in the financial year 2013-14. It means that the actual power deficit in India is less than 1% excluding under priced electricity demand. ABT/DSM mechanism needs improvements to address the requirements of all stake holders (including final electricity consumers) for encouraging least cost electricity generation / tariff based on demand verses availability in the grid. There is a need of well represented Electric Reliability Organization to involve all the grid participants for framing guidelines for power system operation and accreditation which is presently looked after by the CEA

Bulk power purchasers can buy electricity on daily basis for short, medium and long term duration from reverse e-auction facility. In reverse e-auction, availability based tariff /Deviation Settlement Mechanism (DSM) is applied to settle the failed commitments by the electricity sellers or buyers The electricity prices transacted under reverse e-auction facility are far less than the prices agreed under bilateral agreements.

For those power generators who have made power purchase agreements (PPA) with Discoms and need not participate in day ahead market (DAM) trading on daily basis, the pecking order among the power generators in a state is called merit order power generation where the lesser variable generation cost electricity producer is selected out of the available generators to maintain the normal grid frequency.

 What is Availability Tariff ?

     The term Availability Tariff, particularly in the Indian context, stands for a rational tariff structure for power supply from generating stations, on a contracted basis.

 The power plants have fixed and variable costs:

               I.      The fixed cost elements are interest on loan, return on equity, depreciation, O&M expenses, insurance, taxes and interest on working capital.

             II.      The variable cost comprises of the fuel cost, i.e., coal and oil in case of thermal plants and nuclear fuel in case of nuclear plants. In the Availability Tariff mechanism,

The fixed and variable cost components are treated separately. The payment of fixed cost to the generating company is linked to availability of the plant, that is, its capability to deliver MWs on a day-by-day basis. The total amount payable to the generating company over a year towards the fixed cost depends on the average availability (MW delivering capability) of the plant over the year. In case the average actually achieved over the year is higher than the specified norm for plant availability, the generating company gets a higher payment. In case the average availability achieved is lower, the payment is also lower. Hence the name ‘Availability Tariff’. This is the first component of Availability Tariff, and is termed ‘capacity charge’.

The second component of Availability Tariff is the ‘energy charge’, which comprises of the variable cost (i.e., fuel cost) of the power plant for generating energy as per the given schedule for the day. It may specifically be noted that energy charge (at the specified plant-specific rate) is not based on actual generation and plant output, but on scheduled generation. In case there are deviations from the schedule (e.g., if a power plant delivers 600 MW while it was scheduled to supply only 500 MW), the energy charge payment would still be for the scheduled generation (500 MW), and the excess generation (100 MW) would get paid for at a rate dependent on the system conditions prevailing at the time. If the grid has surplus power at the time and frequency is above 50.0 cycles, the rate would be lower. If the excess generation takes place at the time of generation shortage in the system (in which condition the frequency would be below 50.0 cycles), the payment for extra generation would be at a higher rate.

To recapitulate, the Indian version of Availability Tariff comprises of three components: (a) capacity charge, towards reimbursement of the fixed cost of the plant, linked to the plant's declared capacity to supply MWs, (b) energy charge, to reimburse the fuel cost for scheduled generation, and (c) a payment for deviations from schedule, at a rate dependent on system conditions. The last component would be negative (indicating a payment by the generator for the deviation) in case the power plant is delivering less power than scheduled.

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Interesting Facts - Voice Controls for Lighting

A virtual digital assistant is a device with software that can perform tasks for consumers such as looking up information on the internet, playing media and buying products online. It uses speech recognition technology to respond to voice commands.

Amazon Alexa, Apple’s Siri, Google Assistant and Microsoft’s Cortana are the most popular virtual assistant platforms. Market research firm Tractica estimated 390 million people used virtual assistants in 2015 and projected this number to grow to 1 billion in 2018 and 1.8 billion in 2021.

An increasing number of lighting control and home automation manufacturers now offer voice recognition as an input for their systems. Until now, smart lighting in the home was controlled using apps and devices such as keypads, dimmers, switches and sensors. With these methods, homeowners can operate and schedule their lighting. By using a system with a compatible virtual assistant app/device, users can now also control their lighting, shades, thermostats, audio/video, and other smart devices using voice commands.

The benefit, of course, is convenience and enhanced lifestyle. The same benefits of automated home lighting control but with a simple and familiar additional control input. The leading markets are tech-savvy homeowners, people with disabilities and the elderly, who have limited freedom of movement. 

Voice control boosts the cool factor for smart lighting and may even serve as a discussion point—did you know you could use Siri to control your house? For contractors, voice control provides a selling feature for home automation, with lighting control a strong first step that provides benefits that are immediately seen.

Recommending lighting and home automation always begins with the home’s users, their lifestyle and their needs. Many homeowners are likely to start with just a few devices and grow from there based on gaining comfort with devices that are providing value. Exterior lighting is a likely first candidate along with indoor spaces where occupants spend most of their time, such as the kitchen, dining room, living room and bedrooms. As the customer gets comfortable, they can work their way up to more systems and ultimately a home-automation hub that ties everything together.

For voice-controlled lighting, what’s needed is a lighting or home control system, compatible virtual assistant device (phone or speaker) and app, and a robust Wi-Fi connection. These assistants are control-manufacturer-agnostic, meaning they are compatible with a range of products. Examples of lighting and home control systems compatible with various virtual assistants include Home Works QS; and Philips Lighting’s Hue system.

WORKING FUNCTIONS

Using commands such as “Alexa, turn lights to 50 percent,” users can switch, dim, select tailored scenes, or in some cases, change the color of their lighting. If extended to other systems, user commands for scenes such as “home” and “relax” could create custom combinations of lighting, window shades, temperature, and media such as music.

User voice commands pass through the virtual assistant’s external cloud-based service to the control provider’s cloud-based service, which inter operate using an application programming interface. The control provider then sends the appropriate control signal to the controller in the home to execute the command. Control response should be almost immediate.

Many manufacturers offer wireless software updates to simplify delivery of upgrades and security patches. An interesting possibility for home control is If This, Then That integration, which enables systems to respond to each other without the need for user intervention; for example, if a surveillance camera detects motion, the porch lights could automatically turn on.

Smart lighting is typically plug and play and relatively simple to install. For one solution, the contractor swaps out light switches with smart switches then uses an app to connect all devices. Manufacturers offer training on how to install and set up these systems. One way to get comfortable is to try it yourself with a few control points.

While installation is somewhat simple, different systems offer varying levels of size, scalability, hardware, and simplicity. This requires appropriate matching to user needs, installer’s skill level and application characteristics.

Basic Knowledge is necessary to learn manufacturers’ systems, how devices communicate, what they’re inter-operable with, and how they’re set up, as many owners will want assurance everything will work properly. For voice control, the contractor will also need to gain familiarity with how voice commands must be phrased, as there is currently no standardized phrasing for these commands.

Virtual assistants and voice control use is expected to continue to grow, which will impact and add more value to home automation. Electrical contractors who invest in getting to know these systems will likely become more competitive with customers seeking automation’s benefits.

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Electrical Drive - Advantages & Disadvantages

The system which is used for controlling the motion of an electrical machine, such type of system is called an electrical drive. In other words, the drive which uses the electric motor is called electrical drive. The electrical drive uses any of the prime movers like diesel or a petrol engine, gas or steam turbines, steam engines, hydraulic motors and electrical motors as a primary source of energy. This prime mover supplies the mechanical energy to the drive for motion control.

The block diagram of the electrical drive is shown in the figure below. The electrical load like fans, pumps, trains, etc., consists the electrical motor. The requirement of an electrical load is determined regarding speed and torque. The motor which suited the capabilities of the load is chosen for the load drive.

Parts of Electrical Drive

The main parts of the electrical drives are power modulator, motor, controlling unit and sensing units.Their parts are explained below in details.

Power Modulator – The power modulator regulates the output power of the source. It controls the power from the source to the motor in such a manner that motor transmits the speed-torque characteristic required by the load. During the transient operations like starting, braking and speed reversing the excessive current drawn from the source. This excessive current drawn from the source may overload it or may cause a voltage drop. Hence the power modulator restricts the source and motor current.

The power modulator converts the energy according to the requirement of the motor e.g. if the source is DC and an induction motor is used then power modulator convert DC into AC. It also selects the mode of operation of the motor, i.e., motoring or braking.

Control Unit – The control unit controls the power modulator which operates at small voltage and power levels. The control unit also operates the power modulator as desired. It also generates the commands for the protection of power modulator and motor. An input command signal which adjusts the operating point of the drive, from an input to the control unit.

Sensing Unit – It senses the certain drive parameter like motor current and speed. It mainly required either for protection or for closed loop operation.

Advantages of Electrical Drive

Application of Electric Drive

It is used in a large number of industrial and domestic applications like transportation systems, rolling mills, paper machines, textile mills, machine tools, fans, pumps, robots and washing, etc.

The following are the advantages of electrical drive.

1. The electric drive has very large range of torque, speed and power.
2. Their working is independent of the environmental condition.
3. The electric drives are free from pollution.
4. The electric drives operate on all the quadrants of speed torque plane.
5. The drive can easily be started and it does not require any refueling.
6. The efficiency of the drives is high because fewer losses occur on it.

The electric drives have many advantages shown above. 

Because of the following advantages, the mechanical energy already available from a non-electrical prime mover is sometimes first converted into electrical energy by a generator and back to a mechanical energy of an electrical motor. Electrical link thus provides between the non-electrical prime mover and the load impact to the drive flexible control characteristic.

For example – The diesel locomotive produces the diesel energy by the help of the diesel engine. The mechanical energy is converted into an electrical energy by the help of the generator. This electrical energy is used for driving the other locomotive.

Disadvantages of Electrical Drive

The power failure completely disabled the whole of the system.

1. The application of the drive is limited because it cannot use in a place where the power supply is not available.
2. It can cause noise pollution.
3. The initial cost of the system is high.
4. It has a poor dynamic response.
5. The output power obtained from the drive is low.
6. During the breakdown of conductors or short circuit, the system may get damaged due to which several problems occur.
7. Harmonics 

The only main disadvantage of the drive is that sometimes the mechanical energy produced by the prime mover is first converted into electrical energy and then into a mechanical work by the help of the motor. This can be done by the help of the electrical link which is associated with the prime mover and the load.

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Electrical Rescue Techniques

Electric shock accidents are caused by an electric current passing through the body. The effects from a shock can be anything from a tingling to instant death. Knowing what to do in the event of an electrical shock could save a life.

Approaching the accident:

Take a moment to assess the scene and look for any obvious dangers.

Check for the source of the electrical shock. 

Look to see if the victim is still in contact with the source. 

Remember that electricity can flow through the victim and into you. 

• Call emergency number 108/112 as soon as possible.
• Never use water, even if there is a fire, as water can conduct electricity.
• Never enter an area where electrical equipment is used if the floor is wet.
• Use a fire extinguisher made for electrical fires. Fire extinguishers for use on electrical fires will be labelled as a C, BC, or ABC extinguisher.
• Never rush into an accident situation.
• Get the aid of trained electrical personnel if possible.
• Approach the accident scene cautiously. 

Examining the scene:

Visually examine victims to determine if they are in contact with energized conductors.

Metal surfaces, objects near the victim or the earth itself may be energized.

You may become a victim if you touch an energized victim or conductive surface.

Do not touch the victim or conductive surfaces while they are energized.

De-energize electrical circuits if at all possible. 

Methods to de-energize:

An extension or power cord probably powers portable electrical equipment.

Unplug portable electrical equipment to remove power.

Open a disconnecting device or circuit breaker to de-energize fixed electrical equipment. 

Hazards and solutions:

Be alert for hazards such as stored energy, heated surfaces and fire.

If you can’t de-energize the power source use extreme care:

Ensure that your hands and feet are dry.

Wear protective equipment such as low voltage gloves and overshoes if available.

Stand on a clean dry surface.

Use non-conductive material to remove a victim from the conductor. 

High voltage rescue:

Special training is required for rescues if high voltage is present.

Protective equipment such as high voltage gloves and overshoes must be worn.

Special insulated tools should be used 

Insulated tools:

Insulated tools, with high voltage ratings, are a lifesaver!

Use devices such as hot sticks or shotgun sticks to remove a victim from energized conductors.

In some cases, non-conductive rope or cord may be used to remove a victim from a conductor. High voltage rescue:

Rescuing the victim:

Stand on a dry rubber blanket or other insulating material if possible.

Do not touch the victim or conductive material near the victim until the power is off. 

Once power is off, examine the victim to determine if they should be moved.

Give “First Aid.” 

First Aid:

A victim may require Cardio-Pulmonary Resuscitation (CPR).

If the victim is breathing and has a heartbeat, give first aid for injuries and treat for shock.

Ensure the victim gets medical care as soon as possible.

Provide medical personnel with information on voltage level, shock duration & entry/exit points.  The treating/attending physician must have detailed specific information to properly diagnose and care for the victim.  

The physician must determine whether the victim should be sent to a “Trauma or Burn Center.” 

Basics about Electrical Shock

Basically, electrical hazards can be categorized into three types. The first and most commonly recognized hazard is electrical shock. The second type of hazard is electrical burns and the third is the effects of blasts which include pressure impact, flying particles from vaporized conductors and first breath

considerations.

Electric shock occurs when the body becomes part of an electrical circuit. Shocks can happen in three ways.

• A person may come in contact with both conductors in a circuit.

• A person may provide a path between an ungrounded conductor and the ground.

• A person may provide a path between the ground and a conducting material that is in contact with an ungrounded conductor.

The terms high voltage and low voltage are relative terms. In transmission-line terminology, "low voltage" is much higher than the 600 volts. At home, you would not think of 600 volts as being low voltage.

Even when applied to 120-volt circuits, the term low voltage is deceiving. To some people low voltage means low hazard. Actually, low voltage does not necessarily mean low hazard, because potential difference is only one factor making up the dangerous effects of electricity. For purposes of this Lesson,you can think of "low voltage" as being a potential difference of 24-600 volts. 

The extent of injury accompanying electric shock depends on three factors.

• The amount of current conducted through the body.

• The path of the current through the body.

• The length of time a person is subjected to the current.

The amount of the current depends on the potential difference and the resistance. The effects of low current on the human body range from a temporary mild tingling sensation to death. An electric shock can injure you in either or both of the following.

• A severe shock can stop the heart or the breathing muscles, or both.

• The heating effects of the current can cause severe burns, especially at points where the electricity enters and leaves the body.

Other effects include severe bleeding, breathing difficulty, and ventricular fibrillation. In addition, you may strike something, or have some other accident as a result of your response to the shock. The effects of electric current are listed in below. 

The extent of injury accompanying electric shock depends on three factors.

• The amount of current conducted through the body.

• The path of the current through the body.

• The length of time a person is subjected to the current.

The amount of the current depends on the potential difference and the resistance. The effects of low current on the human body range from a temporary mild tingling sensation to death. An electric shock can injure you in either or both of the following.

• A severe shock can stop the heart or the breathing muscles, or both.

• The heating effects of the current can cause severe burns, especially at points where the electricity enters and leaves the body.

Other effects include severe bleeding, breathing difficulty, and ventricular fibrillation. In addition, you may strike something, or have some other accident as a result of your response to the shock. 

Current is the killing factor in electrical shock.  Voltage is important only in that it determines how much current will flow through a given body resistance.  The current necessary to operate a 10 watt light bulb is eight to ten times more current than the amount that would kill a person.  A pressure of 120 volts is enough to cause a current to flow which is many times greater than that necessary to kill. 

The following values are given for human resistance to electrical current in Figure 1: 

Figure 1: Resistance Values

With 120 volts and a skin resistance plus internal resistance totaling 1200 Ohms, we would have 1/10 ampere electric current, that is 100 milli amperes.  If skin contact in the circuit is maintained while the current flows through the skin, the skin resistance gradually decreases.  During this time, proper first aid

can mean the difference between life and death. Sufficient circulation can sometimes be maintained by heart compression, which should always be supported with mouth-to-mouth resuscitation.  This combination of treatments is commonly known as CPR.