Jun 15, 2020

Types of capacitors and their applications

A capacitor can be thought to be like a tank that stores electric charge inside it. The more the capacitance, the more charges a capacitor is capable to store. It comes in various shapes, sizes, and of course, different ratings. It is essentially made of two plates separated by an insulator or a dielectric and has an ample number of uses, and even in our daily life, we use it without even knowing it.

This article aims to give you some insights into the types and uses of one of the most used passive electrical components: the capacitor.

Capacitors
Capacitors (Source: flickr by Eric Schrader)


Before we delve into its applications, let us get familiar with the types of capacitors.

Types of capacitors

While designing a circuit for a specific use, the type of capacitor plays a key role in its proper functioning. Each capacitor has a particular set of specifications, like tolerance, voltage rating, etc.

Capacitors can be broadly classified into two categories: The variable and the fixed capacitors.

Variable capacitor, on the other hand, will have a capacitance value which can be changed. This capacitor has two plates, one of which is fixed and the other one connected to a movable shaft and the capacitance is varied by changing the movable plate.

Fixed capacitor, as the name suggests, this type of capacitor has a fixed capacitance value. Both the conducting plates are immobile and therefore its capacitance value cannot be altered.

Out of these, the fixed type is more commonly used. This article deals with some of the well-known fixed capacitor types.

Ceramic Capacitors:

Ceramic capacitors use ceramic material as a dielectric. You can identify it easily, as most of it comes in a disc shape. The disc is coated with ceramic material and is placed in between the two leads. When a higher capacitance value is needed, multiple layers of ceramic materials are fused together to form the dielectric.

The main advantage of this type of capacitor is that it is a nonpolarized capacitor. This means you can connect it in any direction in your circuit.

Based on their temperature ratings and tolerance, these are classified into three categories: Class 1, Class 2, and Class 3 ceramic capacitors.

Class 1 capacitors are the most stable one, with respect to its temperature tolerance and have good accuracy, while the Class 3 capacitors have relatively poor accuracy and least stability.

Aluminium Electrolytic Capacitors:

Aluminium Electrolytic capacitors have a wide tolerance capacity and hence are one of the most used capacitors. Here, a liquid or gel-type material filled with ions acts as the electrolyte. This electrolyte is responsible for the larger capacitance values of these capacitor types. These are polarized capacitors and hence have to be connected carefully on to a circuit board, keeping their positive/negative leads in mind. They come in a cylindrical shape with two leads of different lengths.

The shorter lead stands for the negative terminal while the longer one stands for its positive terminal. Therefore when you use it in your circuit, remember the golden rule: "The voltage on the positive side must be higher than that of the negative side."

The electrolyte may be either solid polymer or a wet electrolyte and consist of aluminum ions. With higher capacitance values, the electrolytic capacitor comes with drawbacks too. This includes large leakage currents, high-value tolerances and equivalent resistance.

Tantalum Electrolytic Capacitors:

Tantalum electrolytic capacitors are another type of electrolytic capacitor, where the anode is made of Tantalum. The use of Tantalum gives the capacitors higher tolerance value but lower maximum operating voltage than an aluminium electrolytic capacitor, it cannot be used as a direct replacement for the same.

Tantalum capacitors have a very thin dielectric layer and hence higher capacitance value per volume. It shows comparatively good stability and frequency characteristics than other capacitor types.

However, tantalum capacitors pose a risk of a potential failure mode, which may occur during voltage spikes when the anode comes in direct contact with the cathode. This may lead to a chemical reaction depending upon the strength of the energy produced during the process. Therefore while using this capacitor, you will have to use current limiters or thermal fuses as a preventive circuitry.

Film Capacitors:

Film capacitors as the name suggests have dielectrics made of thin plastic film. This film is crafted out through a sophisticated film drawing process. The film can either be metalized or an untreated one, it depends upon the demand of the capacitor characteristics. This capacitor type has good stability with low inductance and is comparatively cheaper than its counterparts. Depending on the type of dielectric used, these film capacitors are classified into various categories like polyester film, plastic film, etc.

These are non-polarized capacitors with desirable characteristics. When compared to an electrolyte capacitor, it has a longer shelf and service life, making it more reliable.

Silver Mica Capacitors:

Silver Mica capacitors use mica, a group of natural minerals as dielectric which is sandwiched between two metal sheets. The specific crystalline binding of mica helps in manufacturing very thin layers of dielectric. This capacitor is popular for its reliability and stability for a small value of capacitances. These low loss capacitors are not polarized and can be made to many high tolerances.


Now that you have got an idea of some of the capacitors and their strengths, let us discuss the prominent areas of application for these capacitors.

Which capacitor can be used where?

Ceramic capacitors

These are probably the most widely produced capacitors, due to their infinite applications. The most prominent area where these capacitors are used is in the resonant circuit of a transmitter station, which requires high precision and high power capacitor. Owing to its non-polarity and availability in a wide range of capacitances, voltage ratings, and size, it is also popular as a general-purpose capacitor. In order to reduce the RF noise in a DC motor, ceramic capacitors can be used across the brushes of the motor.

Electrolyte capacitors

For applications where high capacitances with no need of AC polarization(like a filtering circuit), electrolytic capacitors find their application. Other areas include switching mode power supply, smoothening of input and output in low pass filters. In circuits that have large amplitude and high-frequency signals, these cannot be used as these will have high ESR values.

Tantalum capacitors

These capacitors bear the advantage of having low leakage current along with high capacity and better stability and reliability. This makes them a good choice for sample and holds circuits, power supply filtering circuits of computers and cell phones. They are available in military versions that do not dry out with time and hence, act as a replacement for electrolytic capacitors in military applications.

Film capacitors

These capacitors are popular among the power electronics enthusiast. They are used in almost all the power electronic devices, x-ray machines, phase shifters, and pulsed lasers. Even the switched power supply uses a film capacitor for power factor correction. The lower voltage variants find their roles as decoupling capacitors, filters, and A/D converters. They can be used as a part of conventional circuits as well to smooth out the voltage spikes.

Silver Mica Capacitors

In areas where low capacitance is required but with a need of high stability, such as in power RF circuits, silver Mica capacitors can be used. Its high breakdown voltage makes it suitable for high voltage applications. They exhibit low losses and therefore are popularly used in high frequency tuned circuits like oscillators.


This article has covered the most prominent types of capacitors. Apart from these, there are few other types like the trimmer capacitor, air capacitor, super capacitor, etc. Trimmer capacitor is a variable type and is not that commonly used. Supercapacitors are a combination of few electrolytic capacitors to form a capacitor of a higher value that exhibits the property of both capacitors and a battery bank.

With this, we have come to the end of the article. Hope you got a clear and crisp idea of the capacitor types and their various applications.

Thank you for reading!


Author: Cicy has a master's degree in electrical and electronics engineering with a specialization in Power Electronics. She is a freelance writer who writes to simplify complicated concepts in an understandable language.

May 19, 2020

Essential Tools For Electricians To Work With Wires

Every electrician requires the right set of tools to perform their tasks no matter what that might be. In fact, there is a basic set of tools that every electrician requires. The type of tools available have improved over time there are new and better tools available. The job of an electrician is not easy but with the right set of electrical tools purpose-built for the task like a telecommunication job, networking job, etc.

electrician tools

The availability of more versatile tools makes it possible for an electrician to handle their tasks in a more efficient manner and with greater ease. Each task requires a special list of tools, for example, it is necessary to have a special set of tools when working with wires like a spark plug wire crimper. This article lists the tools an electrician might need to perform their task pertaining to wires.

List of Essentials Tools for an Electrician

An electrician often has the need to work with wires during the course of their work which requires them to have a fixed set of tools go get it right. There are many types of tools necessary like environmental testers here, etc., however, it is possible to classify the tools necessary into two types of tools like hand tools, and power tools. Here is a brief list of tools every electrician will require:

  • Pliers: This is one of the most basic tools that every electrician needs to have. There are mainly two types of pliers available, a side-cutting plier, long-nose, and needle-nose pliers. The side-cutting pliers are useful for heavy-duty cutting and crimping a connector. It is useful for a large number of applications, especially when working with wires or connecting wires.
  • Screwdrivers: A screwdriver is essential when working with various types of fasteners. In fact, there are several multipurpose screwdrivers that an electrician can opt for to use for many different applications including when working with wires.
  • Wire stripper: A wire stripper is essential when working with wires especially when making new connections with wires. This is the most basic tool for an electrician however, the design of this tool has improved over the years with curved handles, better grip, and such that they avoid motion fatigue as well.
  • Wire Crimper: The basic purpose of a crimper is to connect two wires. This is done by placing multiple wires in a connector and using a special wire crimper to make the connection. This tool is very similar to a set of pliers in appearance. The way it works is it deforms either one or both wires, holds them together and makes a joint using a connector. There are different types of crimpers like manual crimper and ratcheted crimper and the type of application dictates which one you may need.
  • Fish tapes & poles: A fish tape helps secure the wires making it safer to use. This is essential when working with live circuits. A fish-pole is essential when working with wires that are in difficult places like the ceilings, down walls, raised floors, as well as where the visibility is low.
  • Measuring Device: A large number of electricians never leave home without their special tool belt and no tool belt is complete without measuring devices of some kind.
  • Labeling machine: A labeling machine might not be essential for connecting two wires or working on wires. However, the process of labeling your work is best accomplished with the help of a labelling machine. Doing so helps save a great deal of time and effort. The labelling machine of this kind can be used for wires, as cable markers, for a rack and frames.
  • Power drills: A power drill is useful for many applications and can be either with a corded one or a cordless one. A power drill is useful to put the wires in place and also place them aesthetically. There are many benefits of using multipurpose power tools.
  • Saws: A power saw is also a very useful tool for any electrician to have.

May 17, 2020

How to fix a power inverter? - Basic Troubleshooting

If you're living in a remote place where you have only Direct current for power, a power inverter is a necessity. The same applies if you're going camping on an RV or have only the SUV for power. Power inverters or digital inverters are extraordinarily efficient when it comes to using batteries as a bigger power source. They will help you turn the DC from your car battery into AC and let you charge your devices, run a laptop or so.

However, if you end up getting a faulty power inverter, and have no other option but to repair it yourself, this article is for you. I'll talk about everything you should know about power inverters, what they are, and how they work. Once you know how your inverter works, you'll get through the processes you should follow to repair it as well. Stay with the process and get your inverter repaired all by yourself.

What is a power inverter?

A power inverter is a power converter device that can convert the DC from a battery into the AC. It is an oscillator that can switch the polarity settings rapidly from DC into AC and make a square wave. With a power inverter, you can use the devices that require AC instead of drawing DC power. You can get both a 220 Volts or 240 Volts current output with an inverter which helps you run any type of device. There are three most popular types for inverters, the pure sine wave inverters, square wave, and the modified sine wave inverters. You'll also find inverters with phase types, single-phase, and three-phase inverters for different types of jobs.

power inverter

Why my inverter isn't working?

Knowing all the reasons why your inverter could go wrong will help you decide the proper troubleshooting techniques. Here are the most common reasons why your inverter might have stopped working or don't function well:

  • Faulty battery connection: The battery you're connecting to the inverter might have a loose connection or no connection at all.
  • Corroded battery terminal: If you're using the inverter for quite a while, the battery terminals may have corroded due to humidity or hydrogen release.
  • A faulty power switch: If your inverter isn't powering up at all, the fault might be with the power switch on the inverter.
  • Discharged battery: Maybe the problem isn't with the inverter at all; instead, your battery may have not enough charge in the first place.
  • A blown-fuse: If you're using it with a permanent terminal and the oscillator goes out of order all of a sudden, the fault might be a blown fuse!

How to fix a power inverter

If you end up getting a faulty inverter that you might be thinking of being dead, it may not be completely out of order after all! If the problem is repairable at home, you can do it yourself by checking the inverter. Here are the things you can do if you have ended up with a faulty power inverter lately:

1. Troubleshoot a faulty power switch

When a power inverter isn't turning on after pushing the power switch, the problem might be with the switch! At first, you have to check if it's okay or not, and the process is simple to do. Unplug the power inverter from its power source, plug in another appliance to it, and turn it on. If it doesn't turn on, you have to get a replacement for the power switch. Call a professional electrician and get a replacement unit for the switch to change it. If you're okay with doing it yourself, you can replace it yourself as well.

2. Check the battery connections

If you're using the setup for a long time, and the inverter isn't working or turning on, the fault might be with the battery. Most of the time, the problem is a loose connection to the battery, which requires you to clean and tighten it up. If the problem isn't with the connector, the battery might have rusted or corroded. Inspect the battery and check for corrosion, if there are any, disconnect and take the battery out and clean it. To clean it, take some baking soda, mixed with hot water, take a stiff toothbrush and scrub the terminal with it after dipping in the mixture. Once the corrosion is removed, clean the connectors and dry them with a paper towel. Reconnect them and try turning the inverter again.

3. A discharged or faulty battery

The fault may not be with the inverter at all in the first place when your power inverter isn't working. The problem might also be with the battery, especially if you're running it for a long time. The battery might have been weakened and discharged quickly, or it might have a fault inside. If your battery is weak, you might have to get it replaced or repaired if possible. If the battery is lead-acid based and running out of acid, you have to get it acid replacement, and that'll be enough.

4. Diagnose the inverter

If the problem isn't in the power switch or the battery, it might be in the inverter itself, and you have to run a diagnosis to resolve that. The best way to do that after getting to know how the system works, get a diagram of the inverter. Once you have the diagram, it's time to check the contact points one by one after opening the housing up. If you find the contact points seem good, move on to the rest of the components. You have to test the voltmeter, followed by the other components. Take extra safety precautions to be sure that you're out of danger, disconnect it from everything first.

5. Order and replace parts

If you have found out the faulty parts, it's time to order their replacements and install them. Get the replacement parts from the same manufacturer if possible, to ensure better quality. Once you have the components, remove the older parts from the inverter, and carefully install the new one. In the removing process, remember how you removed it and which way the part goes. It will help you get the new part in its place correctly.

6. Test the inverter

Once you have the new parts installed to the old faulty parts and shouldered on the places if necessary, now is the testing time. Connect the inverter to your battery and plug it in a controlled and limited power like a low voltage lamp. Now, use a voltmeter to get the reading of the inverter output and see if it works fine. If everything is okay, the machine should work perfectly, and the lamp should light up as well.

FAQ

Here are the most common questions about power inverters people ask about, and you may have interest in:

How do you reset an inverter?
Press and hold on the ON/OFF button for 15 seconds and wait for the charging LED flashes rapidly.
How many watts does an inverter use?
A regular inverter battery will charge at 10 ampere and 12 Volts, which sums up on 120KW.
Will a 2000 watt inverter run a refrigerator?
Yes, a 2000W inverter can power up a 500W deep freezer, including some extra lights as well.

Final Words

A power inverter is indeed a great tool to have as it can help you run devices with DC even if they run with AC. It will keep you on if you don't have a connection to the power grid while after a power outage or while camping. However, if it goes out of order, you can fix it yourself if the problem goes with the ones I've mentioned above. Remember not to keep it connected with the AC adapter when you're working inside the inverter. Disconnect it before starting working with it, or there could be a problem as it works with electricity.

Author: Johnathan Roos is owner of yorator.com where he writes about all the latest power backup tools machinery like different types and powered Generators, inverter and it’s related accessories and use and maintenance information.

May 15, 2020

The Role of an Electrical Engineer in the Construction Industry

In general, the task of an electrical engineer is to design high-voltage equipment such as wiring systems, power distribution systems, generators, and lighting systems etc. Within the construction industry, however, an electrical engineer has many responsibilities especially when it comes to a construction site. In both residential and commercial buildings, while some elements like lighting fixtures and receptacles, or those with a function that requires it are exposed, most components of electrical installations are hidden from sight using access doors. However, electrical systems in building interiors are more evident in industrial settings where there are no drywalls or dropped ceilings to hide junction boxes, conduits, and other accessories.

electrical engineer

At construction sites, it is the duty of electrical site engineers to direct and oversee electrical engineering projects at construction sites, resolve issues, and ensure that work is completed according to specifications. They also balance project management and engineering tasks that range from designing electrical plans to monitoring contractors. It is also the duty of electrical engineers to ensure that plans and work are completed in compliance with local and national electrical codes. To know more about the role of an electrical engineer in the construction industry, this article will discuss them further in detail. Read on to know more.

1. Designing Electrical Systems

It is the duty of electrical engineers to design electrical systems for commercial, residential, and industrial construction projects. High-voltage systems for delivering power and low-voltage applications such as Ethernet and fiber-optic lines are also included. They also have to work closely with designers in order to determine how to effectively incorporate electrical elements, prepare blueprints, and to incorporate electrical elements.

2. Directing Electrical Contractors

Electrical engineers also have the role of directly overseeing and managing teams of electrical contractors and subcontractors. Moreover, they may direct daily activities, answer questions about power needs and electric codes, as well as guide workers throughout the construction process. Mant engineers also work on elements of construction projects themselves, collaborating with electricians and other contractors.

3. Resolving Electrical Issues

When it comes to issues related to electric systems or devices that arise during the construction project, it is also the duty of electrical engineers to resolve such issues. When existing electrical plans and blueprints are no longer viable, or specifications may change requiring a different power configuration resulting from changes to a building’s design or practical concerns, electrical engineers should quickly revise plans to resolve issues and prevent delays.

4. Developing Cost Estimates

Electrical site engineers help develop cost estimates for both material and labor at the onset of the construction planning process. They also estimate manpower and timelines in order to give project managers the information needed for contractor bids and to ensure that the project stays within budget. They also analyze blueprints and site specifications to project the amount of wire, fixtures, and other required materials.

5. Managing Construction Schedules

Managing construction schedules related to electrical elements of job sites is also one of the duties of electrical engineers. They also have to work closely with both planners and utility providers to determine when project milestones will be completed to avoid delays, as well as maintain profitability. They also frequently determine schedules in collaboration with subcontractors in ensuring that electrical work is completed together with other elements of the project.

6. Conduct of System Testing

Throughout the construction process, electrical engineers also conduct tests of electrical systems. This also includes overseeing final inspections of the job and testing individual components or the whole system itself. They also have to check the contractors’ work to ensure that they adhere to local and national electrical codes, safe operation of all devices, and even accurate power delivery.


Lastly, it is also the role of an electrician to ensure that electrical systems requiring more care and protection are safely encased inside quality access doors. 

This article is submitted and sponsored by Access Doors and Panels. For your access door needs, Access Doors and Panels is the place to go. Visit www.accessdoorsandpanels.com today.

May 5, 2020

AC synchronous generator (alternator) - construction and working

NOTE: This article is about alternators. The term 'AC generator' commonly refers to an AC Synchronous generator or alternator. Although, the term "AC generators" includes any type of electricity generator that generates Alternating Current. Read about 'Induction Generators' here. 

Basically, an AC generator is an electrical machine that converts mechanical energy into electrical energy in the form of Alternating Current (AC). Basic principle behind the working of an AC synchronous generator is also Faraday's law of electrical induction, somewhat similar to working of a DC generator.

How does an AC synchronous generator or alternator work?

working of alternator or AC synchronous generator

The above figure illustrates how an alternator or AC synchronous generator work. According to Faraday's law of electromagnetic induction, whenever a conductor moves in a magnetic field,  EMF gets induced across the conductor. If a closed path is provided to the conductor, induced emf causes current to flow in the circuit.

Now, in the above figure, let the conductor coil A-B-C-D is placed in a magnetic field. Direction of the magnetic flux will be from N pole to S pole. The coil is connected to slip rings, and the load is connected through brushes that are resting on the slip rings.

Now, consider the case 1 from the above figure. The coil is rotating clockwise, in this case, the direction of induced current can be given by Fleming's right-hand rule, and it will be along A-B-C-D.

As the coil is rotating clockwise, the position of the coil will be changed after half of the rotational period, as shown in the second case of the above figure. In this case, the direction of the induced current, according to Fleming's right-hand rule, will be along D-C-B-A. It shows that the direction of the current changes after every half of the rotational time period, that means we get an alternating current.

Construction of AC synchronous generator (alternator)

alternator (AC generator) salient pole construction
Salient pole type alternator

The main parts of an alternator, obviously, consists of a stator and a rotor. But, unlike other machines, in most of the alternators, field exciters are rotating and the armature coil is stationary.

Stator: Unlike in a DC machine, the stator of an alternator is not meant to serve a path for magnetic flux. Instead, the stator is used for holding armature winding. The stator core is made up of lamination of steel alloys or magnetic iron, to minimize the eddy current losses.

 

Why armature winding is stationary in an alternator?

  • At high voltages, it is easier to insulate the stationary armature winding, which may be as high as 11 kV or even more in some cases.
  • The generated high voltage output can be directly taken out from the stationary armature. Whereas for a rotary armature, there will be large brush contact drop at higher voltages, also the sparking at the brush surface will be a problem to look after.
  • If the field exciter winding is placed in the rotor, low voltage DC can be transferred safely to the exciter winding via slip-rings.
  • The armature winding can be braced well, to prevent deformation caused by high centrifugal force if it was in the rotor.
Rotor: There are two types of rotor used in an AC synchronous generator/alternator: (i) Salient and (ii) Cylindrical type
  1. Salient pole type: Salient pole type rotor is used in low and medium speed alternators. The construction of an AC synchronous generator of a salient pole type rotor is shown in the figure above. This type of rotor consists of a large number of projected poles (called salient poles), bolted on a magnetic wheel. These poles are also laminated to minimize the eddy current losses. Alternators featuring this type of rotor are large in diameters and short in axial length.

  2. Cylindrical type: Cylindrical type rotors are used in high-speed alternators, especially in turbo-alternators. This type of rotor consists of a smooth and solid steel cylinder having slots along its outer periphery. Field windings are placed in these slots.

A DC supply is given to the rotor winding through the 'slip-rings and brushes' arrangement.

Connecting an alternator in the grid is called as synchronization of alternator, read more about it at the link.

Apr 26, 2020

What is Power Electronics and how does it affect your life?

Ever wondered how 240 Volt AC supply at your home charges the 5V battery of your mobile phone, or how does the DC power from renewable sources like solar, wind supply the required AC power to cater to your domestic needs? If you study deeper into these technologies, you will unravel a circuit where electronic devices play an imperative role in making these things happen. These circuits come under the radar of power electronics, an emerging science relevant to both power engineers and electronics engineers alike.

This article aims to give you a basic idea about the fundamentals of power electronics. It also focusses on the ways this ever ushering subject is prominent in our day to day life.

Let us start by discussing the concept of power electronics and further understand its basic definition.

What is Power Electronics?

Electric energy is undoubtedly one of the imperative parts of our lives. You must have noticed that while all the appliances work on a common source, the AC mains of the house, they all have varied power demands. In order to meet these, different circuits are used where power is changed to the desired form. Like for example, your mobile phone requires a DC power of low value, so a circuit acts between the main supply of your house and the battery to change the input AC to DC while changing the voltage as well, to reach the required low voltage DC power.


power supply unit | power electronics
Image Credit: Wikimedia Commons

These power circuits use solid-state switching devices which are usually seen in low signal applications. There is a dedicated branch in electrical engineering that studies the application of these electronic devices in various power circuits and is known as Power electronics. It not only requires power engineering knowledge but also uses fundamentals from electronics engineering as well.

Power electronics, however, is not a new concept. It dates back to 1902 when Peter Cooper Hewitt developed a mercury arc rectifier to convert AC to DC. Now over 100 years later, power electronics has transcended into almost all the fields of electric energy and denotes a term common for all the power conversion and control circuits.

Basically, power electronic circuits use different passive and active devices like GTO, SCR, etc. These active devices work mainly as switches which help in controlling or converting electric power from one form to another. Various switching techniques like PWM, Soft switching techniques have been developed over the years which helps them to achieve the same. The power conversion and control is possible because of the variable components of electric power. As we know, electric power is the product of voltage, current, and frequency(in case of AC signal). A change in any of these or a combination of these can alter the power as well.

For example, rectifiers, which are one of the most used power electronic circuits, convert AC input power to DC power using different switching devices and passive components such as inductors, resistors, and capacitors by altering the input current from bidirectional AC to unidirectional DC.

Another example of a power electronic circuit is a buck voltage converter, where the input voltage is decreased at the load side, using a combination of solid-state switches and passive electrical components.

Now that you’ve gained an idea of what power electronics is, let us make it more interesting by making you realize how it affects your life, without you being aware of it.

Applications of power electronics in daily life:

We live in an era, where more and more technologies are emerging to explore the various ways to make the best out of renewable energy sources like solar, wind, etc. More people are encouraged to use Solar panels to meet the basic requirement of an average household to reduce the use of conventional energy. The main challenge in implementing these nonconventional methods is the variable and low power generated from them, which cannot be directly used to meet the normal electrical power demands where steady and high power is required. This is where power electronics comes to play. Power from say, a solar panel is conditioned to a steady and higher power AC supply using combination of different power electronic circuits such as Buck/boost converter, inverter, rectifier.

Another prominent use is in those little adapters of your laptop/tablet/mobile devices where 240V AC is converted to 5V DC to charge their batteries. Take a look around you, and you’ll find power electronic circuits in the regulator of your fan, the voltage stabilizer of your high power devices like AC, TV, refrigerators etc.. The mood lights of your bedroom are one of the simplest and latest implementations of the power control circuit.

Power electronics implementation can also be seen in your kitchen. The induction heating used to cook food on an induction stove is a classic example where the heat is controlled via a power control circuit which regulates the current which is responsible for the heating.

The uninterrupted power supply systems that continue to power up your computer during power fails, are another example of a power electronics application. The current trend of electric vehicles also uses power electronic circuits. Industries use power control circuits in traction, trolly, fork lifts etc.

The application of power electronics is overwhelming and the list is endless. All these circuits differ in the use of switches like GTO, SCR, IGBT, MOSFET, BJT, and different switching techniques that are used for different applications to suit the need.

Conclusion

Electrical energy is one of the most used forms of energy and electric power conversion and control is one of the most growing subsidiaries of electrical engineering. Power electronics is a combination of power circuits mixed with the low signal electronic circuits to meet these ever-fluctuating electric power demands. These circuits involve high power rated switches like GTO, SCR, BJT, MOSFET, etc and different passive components to get the desired output. From a simple regulator at your home to the traction circuits at various industries, you can find the application of power electronics in almost every field.

With the current trend of renewable energy garnering more attention, power electronics is undoubtedly not only the present but the future of electrical engineering across the globe.


Author: Cicy has a master's degree in electrical and electronics engineering with a specialization in Power Electronics. She is a freelance writer who writes to simplify complicated concepts in an understandable language.

Oct 21, 2019

What is inverter generator? And How It is Different from Conventional Generator?

Many times you may have heard that the inverter generators are fuel-efficient and quieter than conventional generators. Have you wondered why is that so?
Well, today we are going to answer all your queries regarding inverter generators, so keep reading.
But before this you need to understand how alternator works. The alternator is almost the same as generator however there is one big difference. In alternator, the rotor is excited with DC current and thus strong magnetic field is produced by rotor. And when the rotor rotates, the stator cuts these magnetic field and hence the electricity is produced which is collected through the stator.
But in case of generator, armature winding rotates in a fixed magnetic field and the stator produces this magnetic field with the help of excitation winding. The electricity is collected through the rotor with the help of carbon brushes and they wear out quickly so you need to replace them frequently.

Difference between inverter generator and conventional generator




The conventional generator or non-inverter generator produces directly AC current, whereas the inverter generator produces AC current, then converts it to DC current and then again converts it back to AC current, and it has many advantages which we will discuss later. An inverter generator is also fuel-efficient; let’s understand this by this equation.



This is the equation of rotor speed of the generator, and all the generators, including inverter generator, alternator, and the conventional generator, produce the power based on this equation.
Countries like America and Canada use the 60Hz frequency, so here f=60 and P is number poles of any particular generator. Almost all the generators (except for generators used in Hydropower) have two pole arrangement.
Now, as you know, the frequency of the current must be 60Hz, and if the frequency fluctuates even the slightest, let’s say 58Hz or 61Hz, then it may damage your appliances.
If we do the simple math, then to get f=60, the value of n must be 3600 RPM (Rotations per Minute). This means that the rotor of the generator must run at a constant 3600 RPM no matter what. And if this speed increases or decreases, then it may change the frequency of output current.
So now, you know that conventional generator must run at 3600 RPM constantly no matter what amount of power is asked of it.
Let’s understand it by this example. Suppose you have a generator that can supply 1000 watts of continuous power (not peak power), and you want to run a 100-watt bulb. So it will burn some fuel, right? Now let’s say you want to run an electronic device of 500 watts. In both cases the generator will definitely consume fuel, but in both cases the generator must run at 3600 RPM to produce 60Hz current.
So as you can see, there is definitely wastage of fuel; not that high, but some amount of fuel does go to waste.
Well, now let’s understand the inverter generator. As I said earlier, the inverter generator produces power in three stages; first, it produces AC power, then converts it to DC power and then again converts it back to AC power.
This is especially helpful when you need less power from the inverter generator because the generator will rotate at a lower speed (consuming less fuel) and produce power with low frequency. Then the rectifier will convert it to DC power, and then the inverter circuit will convert it to 120V 60Hz power.
Let’s understand it by this example. Suppose you have an inverter generator that can supply 1000 watts continuously, and you want to run a 100-watt bulb. And then you want to run a 500-watt device on it. Now in the case of a 100-watt bulb, the inverter generator will burn less fuel (because it does not need to produce 60Hz supply; hence, the rotating speed will be very low) compared to the conventional generator. And in the case of a 500-watt device, the rotor will rotate accordingly (far less than 3600 RPM) to produce the required power.

[Also Read: Synchronous Generators vs. Induction Generators]

Noise Output

So now you know their difference in fuel efficiency, let’s understand how they differ in terms of noise output.
The generator produces noise mainly due to combustion of fuel, and rotation of mechanical gears. This noise increases when the load demand is increased because in order to cut those intensive magnetic fields of a stator, the rotor needs high torque. And that is why the high amount of fuel is ignited in the chamber and hence, noise production increases too.
The portable generator will make the same amount of noise up to 85% load capacity, but above that, its noise will increase even further. But in the case of an inverter generator, it automatically adjusts its speed according to power demand; thus, it will make less noise at low power requirements.
Moreover, the portable inverter generators are integrated with special mufflers and sound dampening materials, which helps in reducing the noise to a great extent.

So which generator should you use?

Well, the answer is complicated because it depends on your power requirements. As you know, the inverter generators are very expensive and they are designed to be portable and compact; thus, their power output is also low.
If you need a generator for regular use and that too for load demand above 60 or 70%, then you are better off buying a conventional generator because its initial cost is low. But if you need a quiet generator with clean power output, then you should opt-in for an inverter generator.