Understanding Distance Protection & Numerical Relays

Before going to Distance Protection First see what is Protection System in Power System & Transmission Lines.

• The purpose of protective relays and system is to operate the correct CB so as to disconnect only the faulty Equipment/Ckt. From the system as quickly as possible, Thus minimizing the trouble & damage caused by fault when they do occur.

•  Most faults are shunt faults which are characterize by increase in current, reduction in voltage, power factor & frequency.

Primary & Backup Protection

• Primary relaying or also called Group-1, Main-1 or Stage-1, the function of this is first line of defense for protecting the eq. whereas the backup relaying (Group-2, Main-2 or Stage-2) works only when primary relaying fails.

• Time delay and relay settings of backup relays are higher than the primary relays.

• In distance protection Characteristics are also different for both primary & backup relays.

Understanding Distance Protection

 Why Distance Protection

> Since the impedance of a transmission line is proportional to its length, for distance measurement it is appropriate to use a relay capable of measuring the impedance of a line up to a predetermined point (the reach point). Such a relay is described as a distance relay and is designed to operate only for faults occurring between the relay location and the selected reach point, thus giving discrimination for faults that may occur in different line sections.

> The basic principle of distance protection involves the division of the voltage at the relaying point by the measured current. The apparent impedance so calculated is compared with the reach point impedance.

If the measured impedance is less than the reach point impedance, it is assumed that a fault exists on the line between the relay and the reach point. The reach point of a relay is the point along the line impedance locus that is intersected by the boundary characteristic of the relay. Since this is dependent on the ratio of voltage and current and the phase angle between them, it may be plotted on an R/X diagram. The loci of power system impedances as seen by the relay during faults, power swings and load variations may be plotted on the same diagram and in this manner the performance of the relay in the presence of system faults.

DISTANCE RELAY CHARACTERISTICS

Some numerical relays measure the absolute fault impedance and then determine whether operation is required according to impedance boundaries defined on the R/X diagram. Traditional distance relays and numerical relays that emulate the impedance elements of traditional relays do not measure absolute impedance.

They compare the measured fault voltage with a replica voltage derived from the fault current and the zone impedance setting to determine whether the fault is within zone or out-of-zone.

Impedance Characteristics

Relay measuring elements whose functionality is based on the comparison of two independent quantities are essentially either amplitude or phase comparators.

For the impedance elements of a distance relay, the quantities being compared are the voltage and current measured by the relay. There are numerous techniques available for performing the comparison, depending on the technology used. They vary from balanced-beam (amplitude comparison) and induction cup (phase comparison) electromagnetic relays, through diode and operational amplifier comparators in static-type distance relays, to digital sequence comparators in digital relays and to algorithms used in numerical relays.

Plain Impedance Characteristic

 

This characteristic takes no account of the phase angle between the current and the voltage applied to it; for this reason its impedance characteristic when plotted on an R/X diagram is a circle with its center at the origin of the co-ordinates and of radius equal to its setting in ohms.

Operation occurs for all impedance values less than the setting, that is, for all points within the circle. The relay characteristic, shown in Figure 11.7, is therefore non directional, and in this form would operate for all faults along the vector AL and also for all faults behind the Bus bars up to an impedance AM. It is to be noted that A is the relaying point and RAB is the angle by which the fault current lags the relay voltage for a fault on the line AB and RAC is the equivalent leading angle for a fault on line AC. Vector AB represents the impedance in front of the relay between the relaying point A and the end of line AB. Vector AC represents the impedance of line AC behind the relaying point. AL represents the reach of instantaneous Zone 1 protection, set to cover 80% to 85% of the protected line.

Disadvantages of Impedance Char.

A relay using this characteristic has three important disadvantages:

i. it is non-directional; it will see faults both in front of and behind the relaying point, and therefore requires a directional element to give it correct discrimination

ii. it has non-uniform fault resistance coverage

iii. it is susceptible to power swings and heavy loading of a long line, because of the large area covered by the impedance circle.

Impedance relay with Directional element

• Directional control is an essential discrimination quality for a distance relay, to make the relay non-responsive to faults outside the protected line. This can be obtained by the addition of a separate directional control element.

The impedance characteristic of a directional control element is a straight line on the R/X diagram, so the combined characteristic of the directional and impedance relays is the semi-circle APLQ shown in Figure below:

Mho Relay

 

The mho impedance element is generally known as such  because its characteristic is a straight line on an admittance diagram. It cleverly combines the discriminating qualities of both reach control and directional control, thereby eliminating the ‘contact race’ problems that may be encountered with separate reach and directional control elements. This is achieved by the addition of a polarising signal. Mho impedance elements were particularly attractive for economic reasons where electromechanical relay elements were employed. As a result, they have been widely deployed worldwide for many years and their advantages and imitations are now well understood. For this reason they are still emulated in the algorithms of some modern numerical relays.

• The characteristic of a mho impedance element, when plotted on an R/X diagram, is a circle whose circumference passes through the origin, as illustrated in Figure (b).

This demonstrates that the impedance element is inherently directional and such that it will operate only for faults in the forward direction along line AB.

The impedance characteristic is adjusted by setting Zn, the impedance reach, along the diameter and ϕ, the angle of displacement of the diameter from the R axis. Angle ϕ is known as the Relay Characteristic Angle (RCA). The relay operates for values of fault impedance   ZF within its characteristic.

 

Third zone and bus bar back-up zone

 

• In this application it is used in conjunction with mho measuring units as a fault detector and/or Zone 3 measuring unit. So, with the reverse reach arranged to extend into the busbar zone, as shown in Figure 11.10(a), it will provide back-up protection for busbar faults. This facility can also be provided with quadrilateral characteristics. A further benefit of the Zone 3 application is for Switch-on-to-Fault (SOTF) protection, where the Zone 3 time delay would be bypassed for a short period immediately following line energisation to allow rapid clearance of a fault anywhere along the protected line.

Quadrilateral Characteristic

 

• This form of polygonal impedance characteristic is shown in Figure 11.15. The characteristic is provided with forward reach and resistive reach settings that are independently adjustable. It therefore provides better resistive coverage than any mho-type characteristic for short lines. This is especially true for earth fault impedance measurement, where the arc resistances and fault resistance to earth contribute to the highest values of fault resistance. To avoid excessive errors in the zone reach accuracy, it is common to impose a maximum resistive reach in terms of the zone impedance reach.

Recommendations in this respect can usually be found in the appropriate relay manuals.

• Polygonal impedance characteristics are highly flexible in terms of fault impedance coverage for both phase and earth faults. For this reason, most digital and numerical distance relays now offer this form of characteristic.

Protection Features of Numerical Distance relays

Phase and earth fault distance protection, each with up to 5 independent

zones of protection. Standard and customised signalling schemes are available to  give fast fault clearance for the whole of the protected line or cable.

>  Directional earth fault protection (DEF)

• Undervoltage Protection
• Overvoltage Protection
• Directional or non-directional negative sequence overcurrent protection – This  element can provide backup protection for many unbalanced fault conditions.
•  Switch on to fault (SOTF) protection – These settings enhance the protection applied for manual circuit breaker closure.
• Trip on reclose (TOR) protection – These settings enhance the protection applied on auto reclosure of the circuit breaker.
• Power swing blocking – Selective blocking of distance protection zones ensures stability during the power swings experienced on sub-transmission and transmission    systems.

Non-Protection Features

• Autoreclosure with Check synchronism ,

• Measurements – Selected measurement values polled at the line/cable terminal, available for display on the relay or accessed from the serial communications facility.

•  Fault/Event/Disturbance Records – Available from the serial communications or on the relay display (fault and event records only).

• Distance to fault locator – Reading in km, miles or % of line length.

Quadrilateral Characteristic of Typical MICOM P444 Relay

 

 

Zones of Protection

Zone-1

 

The zone 1 elements of a distance relay should be set to cover as much of the  protected line as possible, allowing instantaneous tripping for as many faults as possible. In most applications the zone 1 reach (Z1) should not be able to respond to faults beyond the protected line. For an underreaching application the zone 1 reach must therefore be set to account for any possible overreaching errors. These errors come from the relay, the VTs and CTs and inaccurate line impedance data. It is therefore recommended that the reach of the zone 1 distance elements is restricted to 80 – 85% of the protected line impedance (positive phase sequence line impedance), with zone 2 elements set to cover the final 20% of the line.

Here: Ra = Relay at bus A, Rb = Relay at bus B,

Z1 = Zone-1 Reach for Relay Ra = 80-85% Zab(Imp. Of Line AB),

Z2 = Zone-2 Reach for Relay Ra = 120% Zab or Zab+(< 50% Zbc),

Z3 = Zone-3 Reach for Relay Ra = 120%( Zab+Zbc),

Z4= Zone-4 Reach, reverse zone reach for relay Ra= 10-25% of Zab or

Z4 ≥ ((Remote zone 2 reach, Rb) x 120%) minus the protected line impedance

Zone-2

The zone 2 elements should be set to cover the 20% of the line not covered by zone 1.  Allowing for underreaching errors, the zone 2 reach (Z2) should be set in excess of 120% of the protected line impedance for all fault conditions. Where aided tripping schemes are used, fast operation of the zone 2 elements is required. It is therefore beneficial to set zone 2 to reach as far as possible, such that faults on the protected line are well within reach. A constraining requirement is that, where possible, zone 2 does not reach beyond the zone 1 reach of adjacent line protection. Where this is not possible, it is necessary to time grade zone 2 elements of relays on adjacent lines.

For this reason the zone 2 reach should be set to cover ≤50% of the shortest adjacent line impedance, if possible. When setting zone 2 earth fault elements on parallel  circuits, the effects of zero sequence mutual coupling will need to be accounted for.

The mutual coupling will result in the Zone 2 ground fault elements underreaching.

Zone-3

The zone 3 elements would usually be used to provide overall back-up protection for adjacent circuits. The zone 3 reach (Z3) is therefore set to approximately 120% of the combined impedance of the protected line plus the longest adjacent line. A higher  apparent impedance of the adjacent line may need to be allowed where fault current can be fed from multiple sources or flow via parallel paths.

Zone-4

The zone 4 elements would typically provide back-up protection for the local busbar,where the offset reach is set to 25% of the zone 1 reach of the relay for short lines (<30km) or 10% of the zone 1 reach for long lines. Setting zone 4 in this way would also satisfy the requirements for Switch on to Fault, and Trip on Reclose protection, as described in later sections. Where zone 4 is used to provide reverse directional decisions for Blocking or Permissive Overreach schemes, zone 4 must reach further behind the relay than zone 2 for the remote relay. This can be achieved by setting:

Z4 ≥ ((Remote zone 2 reach) x 120%) minus the protected line impedance.

 

References : Areva Micom Numerical Relays

Now Scan Your Documents even from your mouse: LG introduces mouse scanner

Have you ever thought that your computer mouse can even scan your documents. LG Electronics has announced the launch of the LSM-100 mouse, which comes with a built-in scanner. The concept seems pretty nice, but how do you operate it? Well, LG’s given a brief operating manual and from the looks of it, it appears quite convenient. While holding the Smart Scan button on the left side of the mouse, the user swipes the mouse over the material to be scanned. The scanned image can then be saved in a variety of file types – PNG, JPEG, TIFF, BMP, PDF, XLS and DOC – or can be dragged and dropped into the desired application. Users can also perform OCR (optical character recognition) editing of scanned files, as well as send them as e-mails.

It is having a camera phone like camera that serves to scan the documents. You can scan a document in A4 and upto A3 size. This mouse is come with a software from which you can directly share the scan document directly to facebook, twitter and other sites and email also.

There is some limitations that you have to drag several times over a document to reproduce full doc, also for photo scanning this is not good as traditional scanner. But in form of mouse you can done your daily office needs in a fast way.

for more information see – http://www.lg.com/us/computer-products/it-accessories/LG-MCL1ULOGE.jsp

 

Now Facebook messenger for windows 7

Facebook has launched messenger service for windows, currently it is available for windows 7.

Messenger is a trial application that lets you use Facebook without being on http://www.facebook.com. While you surf the web or use other applications on your computer, you can:

• Chat and message with your friends on Facebook
• See the latest updates from your friends in ticker
• Get quick notifications about what’s going on

During this trial period, facebook are plan on rolling out changes to the app and expect outages and periods of instability as make improvements.

Download this app from here ( after clicking one Facebook page will open , on this page click on the first question “what is messenger for windows” then click on the link “one time setup”).

Now charge your mobile batteries from your shoes

New tech could power portable gadgets with every step

In future it may be possible that your shoes will also work as a battery charger of your mobile or any other gadgets.

Developers are working on it and it may be possible that these shoes will be available in next 1-2 years.

As smartphones and other portable gadgets push the limits of handheld computing, their hunger for electricity has only increased—with no end in sight. A new technology aims to address this issue, not by seeking bigger and better batteries but by looking instead to the shoes on our feet.

When we walk, our bodies create up to 40 watts of mechanical power as heat when our feet strike the ground. A special electricity-generating cushion placed inside the soles of a regular pair of shoes can transform some of that footfall power into several watts of electricity. Over the course of a single day, the generated energy, which gets stored in a small battery in the sole, provides enough electricity for a pedestrian to extend her smartphone’s battery life, for a soldier to augment his portable power needs in the field, or for someone in a developing nation without an electrical grid to power a night’s worth of LED home light use.

The idea of harvesting body energy for portable electronics is certainly not new, although some of this technology is. In 1996, Thad Starner at the MIT Media Lab that piezoelectric generators—solids that generate tiny currents when stretched or stressed—could theoretically generate up to 5 W of electricity at a brisk walking pace.

Today’s best known piezoelectric footwear—Nike+ running shoes—aren’t really harvesting energy at all.

According to  Tom Krupenkin, associate professor of mechanical engineering at the University of Wisconsin–Madisonthe  liquid metals such as mercury and Galinstan, a gallium indium tin alloy  when set on a dielectric-coated conductive substrate with a voltage applied across it, a droplet of liquid metal deforms and spreads across the substrate. When the process is reversed, and the liquid metal in a micro fluid device is moved, it induces a voltage.

According to Krupenkin, InStep is developing a shoe sole that would store the energy from each footfall in an embedded battery. InStep says it would provide up to 10 W from each foot—enough to power a mini Wi-Fi hot spot that communicates with your smartphone via Bluetooth and handles the phone’s biggest battery-draining function: long-range communication with cellphone towers.

Resource : IEEE.ORG

Cyber Security Guide Part 7: Know Basics of Virus

Virus Basics

This information gives an introduction to viruses and ways to avoid them.

 

What is a virus?
A computer virus is a program that spreads by first infecting files or the system areas of a computer or network router’s hard drive and then making copies of itself. Some viruses are harmless, others may damage data files, and some may destroy files. Viruses used to be spread when people shared pen drives and other portable media, now viruses are primarily spread through email messages.

Unlike worms, viruses often require some sort of user action (e.g., opening an email attachment or visiting a malicious web page) to spread.

What do viruses do?
A virus is simply a computer program — it can do anything that any other program you run on your computer can do. Some viruses are designed to deliberately damage files, and others may just spread to other computers.

What is a worm?
A worm is a type of virus that can spread without human interaction. Worms often spread from computer to computer and take up valuable memory and network bandwidth, which can cause a computer to stop responding. Worms can also allow attackers to gain access to your computer remotely.

What is a Trojan horse?
A Trojan horse is a computer program that is hiding a virus or other potentially damaging program. A Trojan horse can be a program that purports to do one action, when in fact, it is performing a malicious action on your computer. Trojan horses can be included in software that you download for free or as attachments in email messages.

Can I get a virus by reading my email messages?
Most viruses, Trojan horses, and worms are activated when you open an attachment or click a link contained in an email message. If your email client allows scripting, then it is possible to get a virus by simply opening a message. It’s best to limit what HTML is available in your email messages. The safest way to view email messages is in plain text.

How can I avoid a virus infection from email?
Most users get viruses from opening and running unknown email attachments. Never open anything that is attached to an email message unless you know the contents of the file. If you receive an attachment from a familiar email address, but were not expecting anything, you should contact the sender before opening the attachment. If you receive a message with an attachment and you do not recognize the sender, you should delete the message.

Selecting the option to view your email messages in plain text, not HTML, will also help you to avoid a virus.

What are some tips to avoid viruses and lessen their impact?

• Install anti-virus software from a reputable vendor. Update it and use it regularly.
• In addition to scanning for viruses on a regular basis, install an “on access” scanner (included in most anti-virus software packages) and configure it to start each time you start up your computer. This will protect your system by checking for viruses each time you run an executable file.
• Use a virus scan before you open any new programs or files that may contain executable code. This includes packaged software that you buy from the store as well as any program you might download from the internet.
• If you are a member of an online community or chat room, be very careful about accepting files or clicking links that you find or that people send you within the community.
• Make sure you back up your data (documents, bookmark files, important email messages, etc.) on disc so that in the event of a virus infection, you do not lose valuable work.

Know about Cloud Computing

The Basics of Cloud Computing

What is the cloud?

 Cloud computing is receiving a great deal of attention, both in publications and among users, from individuals at home to the Big Giants of Corporate sector. Yet it is not always clearly defined.

Cloud computing is a subscription-based service where you can obtain networked storage space and computer resources. One way to think of cloud computing is to consider your experience with email. Your email client, if it is Yahoo!, Gmail, Hotmail, and so on, takes care of housing all of the hardware and software necessary to support your personal email account. When you want to access your email you open your web browser, go to the email client, and log in. The most important part of the equation is having internet access. Your email is not housed on your physical computer; you access it through an internet connection, and you can access it anywhere.

If you are on a trip, at work, or down the street getting coffee, you can check your email as long as you have access to the internet. Your email is different than software installed on your computer, such as a word processing program. When you create a document using word processing software, that document stays on the device you used to make it unless you physically move it. An email client is similar to how cloud computing works. Except instead of accessing just your email, you can choose what information you have access to within the cloud.

How can you use the cloud?

 The cloud makes it possible for you to access your information from anywhere at any time. While a traditional computer setup requires you to be in the same location as your data storage device, the cloud takes away that step. The cloud removes the need for you to be in the same physical location as the hardware that stores your data. Your cloud provider can both own and house the hardware and software necessary to run your home or business applications.

This is especially helpful for businesses that cannot afford the same amount of hardware and storage space as a bigger company. Small companies can store their information in the cloud, removing the cost of purchasing and storing memory devices. Additionally, because you only need to buy the amount of storage space you will use, a business can purchase more space or reduce their subscription as their business grows or as they find they need less storage space.

One requirement is that you need to have an internet connection in order to access the cloud. This means that if you want to look at a specific document you have housed in the cloud, you must first establish an internet connection either through a wireless or wired internet or a mobile broadband connection. The benefit is that you can access that same document from wherever you are with any device that can access the internet. These devices could be a desktop, laptop, tablet, or phone. This can also help your business to function more smoothly because anyone who can connect to the internet and your cloud can work on documents, access software, and store data.

Imagine picking up your smartphone and downloading a .pdf document to review instead of having to stop by the office to print it or upload it to your laptop. This is the freedom that the cloud can provide for you or your organization.

Types of clouds

 There are different types of clouds that you can subscribe to depending on your needs. As a home user or small business owner, you will most likely use public cloud services.

1.  Public Cloud – A public cloud can be accessed by any subscriber with an internet

connection and access to the cloud space.

2.  Private Cloud – A private cloud is established for a specific group or organization

and limits access to just that group.

3.  Community Cloud – A community cloud is shared among two or more

organizations that have similar cloud requirements.

4.  Hybrid Cloud – A hybrid cloud is essentially a combination of at least two clouds,

where the clouds included are a mixture of public, private, or community.

Choosing a cloud provider

Each provider serves a specific function, giving users more or less control over their cloud depending on the type. When you choose a provider, compare your needs to the cloud services available. Your cloud needs will vary depending on how you intend to use the space and resources associated with the cloud. If it will be for personal home use, you will need a different cloud type and provider than if you will be using the cloud for business. Keep in mind that your cloud provider will be pay-as-you-go, meaning that if your technological needs change at any point you can purchase more storage space (or less for that matter) from your cloud provider.

There are three types of cloud providers that you can subscribe to: Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS). These three types differ in the amount of control that you have over your information, and conversely, how much you can expect your provider to do for you. Briefly, here is what you can expect from each type.

1.  Software as a Service – A SaaS provider gives subscribers access to both  resources and applications. SaaS makes it unnecessary for you to have a  physical copy of software to install on your devices. SaaS also makes it easier to  have the same software on all of your devices at once by accessing it on the cloud. In a SaaS agreement, you have the least control over the cloud.

2.  Platform as a Service – A PaaS system goes a level above the Software as a    Service setup. A PaaS provider gives subscribers access to the components that they require to develop and operate applications over the internet.

3.  Infrastructure as a Service – An IaaS agreement, as the name states, deals primarily with computational infrastructure. In an IaaS agreement, the subscriber completely outsources the storage and resources, such as hardware and software, that they need.

As you go down the list from number one to number three, the subscriber gains more control over what they can do within the space of the cloud. The cloud provider has less control in an IaaS system than with an SaaS agreement.

What does this mean for the home user or business looking to start using the cloud? It means you can choose your level of control over your information and types of services that you want from a cloud provider. For example, imagine you are starting up your own small business. You cannot afford to purchase and store all of the hardware and software necessary to stay on the cutting edge of your market. By subscribing to an Infrastructure as a Service cloud, you would be able to maintain your new business with just as much computational capability as a larger, more

established company, while only paying for the storage space and bandwidth that you use. However, this system may mean you have to spend more of your resources on the development and operation of applications. As you can see, you should evaluate your current computational resources, the level of control you want to have, your financial situation, and where you foresee your business going before signing up with a cloud provider.

If you are a home user, however, you will most likely be looking at free or low-cost cloud services (such as web-based email) and will not be as concerned with many of the more complex cloud offerings.

After you have fully taken stock of where you are and where you want to be, research into each cloud provider will give you a better idea of whether or not they are right for you.

Security

The information housed on the cloud is often seen as valuable to individuals with malicious intent. There is a lot of personal information and potentially secure data that people store on their computers, and this information is now being transferred to the cloud. This makes it critical for you to understand the security measures that your cloud provider has in place, and it is equally important to take personal precautions to secure your data.

The first thing you must look into is the security measures that your cloud provider already has in place. These vary from provider to provider and among the various types of clouds. What encryption methods do the providers have in place? What methods of protection do they have in place for the actual hardware that your data will be stored on? Will they have backups of my data? Do they have firewalls set up? If you have a community cloud, what barriers are in place to keep your information separate from other companies? Many cloud providers have standard terms and conditions that may answer these questions, but the home user will probably have little negotiation room in their cloud contract. A small business user may have slightly more room to discuss the terms of their contract with the provider and will be able to ask these questions during that time. There are many questions that you can ask, but it is important to choose a cloud provider that considers the security of your data as a major concern.

No matter how careful you are with your personal data, by subscribing to the cloud you will be giving up some control to an external source. This distance between you and the physical location of your data creates a barrier. It may also create more space for a third party to access your information. However, to take advantage of the benefits of the cloud, you will have to knowingly give up direct control of your data. On the converse, keep in mind that most cloud providers will have a great deal of knowledge on how to keep your data safe. A provider likely has more resources and expertise than the average user to secure their computers and networks.

Conclusions

To summarize, the cloud provides many options for the everyday computer user as well as large and small businesses. It opens up the world of computing to a broader range of uses and increases the ease of use by giving access through any internet connection. However, with this increased ease also come drawbacks. You have less control over who has access to your information and little to no knowledge of where it is stored. You also must be aware of the security risks of having data stored on the cloud. The cloud is a big target for malicious individuals and may have disadvantages because it can be accessed through an unsecured internet connection.

If you are considering using the cloud, be certain that you identify what information you will be putting out in the cloud, who will have access to that information, and what you will need to make sure it is protected. Additionally, know your options in terms of what type of cloud will be best for your needs, what type of provider will be most useful to you, and what the reputation and responsibilities of the providers you are considering are before you sign up.

Cyber Security Guide 6: Secure Yourself Using Public Wi-Fi hotspots

Wi-Fi hotspots in coffee shops, libraries, airports, hotels, universities, and other public places are convenient, but they’re often not secure. When using a hotspot, it’s best to send information only to websites that are fully encrypted.

You can be confident a hotspot is secure only if it asks you to provide a WPA password. If you’re not sure, treat the network as if it were unsecured.

How Encryption Works

Encryption is the key to keeping your personal information secure online. Encryption scrambles the information you send over the internet into a code so that it’s not accessible to others. When using wireless networks, it’s best to send personal information only if it’s encrypted – either by an encrypted website or a secure Wi-Fi network. An encrypted website protects only the information you send to and from that site. A secure wireless network encrypts all the information you send using that network.

How to Tell If a Website is Encrypted

If you send email, share digital photos and videos, use social networks, or bank online, you’re sending personal information over the internet. The information you share is stored on a server – a powerful computer that collects and delivers content. Many websites, such as banking sites, use encryption to protect your information as it travels from your computer to their server.

To determine if a website is encrypted, look for https at the beginning of the web address (the “s” is for secure). Some websites use encryption only on the sign-in page, but if any part of your session isn’t encrypted, your entire account could be vulnerable. Look for https on every page you visit, not just when you sign in.

Don’t Assume a Wi-Fi Hotspot is Secure

Most Wi-Fi hotspots don’t encrypt the information you send over the internet and are not secure.

If you use an unsecured network to log in to an unencrypted site – or a site that uses encryption only on the sign-in page – other users on the network can see what you see and what you send. They could hijack your session and log in as you. New hacking tools – available for free online – make this easy, even for users with limited technical know-how. Your personal information, private documents, contacts, family photos, and even your login credentials could be up for grabs.

An imposter could use your account to impersonate you and scam people you care about. In addition, a hacker could test your username and password to try to gain access to other websites – including sites that store your financial information.

Protect Yourself When Using Public Wi-Fi

So what can you do to protect your information? Here are a few tips:

• When using a Wi-Fi hotspot, only log in or send personal information to websites that you know are fully encrypted. To be secure, your entire visit to each site should be encrypted – from the time you log in to the site until you log out. If you think you’re logged in to an encrypted site but find yourself on an unencrypted page, log out right away.
• Don’t stay permanently signed in to accounts. When you’ve finished using an account, log out.
• Do not use the same password on different websites. It could give someone who gains access to one of your accounts access to many of your accounts.
• Many web browsers alert users who try to visit fraudulent websites or download malicious programs. Pay attention to these warnings, and keep your browser and security software up-to-date.
• If you regularly access online accounts through Wi-Fi hotspots, use a virtual private network (VPN). VPNs encrypt traffic between your computer and the internet, even on unsecured networks. You can obtain a personal VPN account from a VPN service provider. In addition, some organizations create VPNs to provide secure, remote access for their employees.
• Some Wi-Fi networks use encryption: WEP and WPA are the most common. WPA2 is the strongest. WPA encryption protects your information against common hacking programs. WEP may not. If you aren’t certain that you are on a WPA network, use the same precautions as on an unsecured network.
• Installing browser add-ons or plug-ins can help, too. For example, Force-TLS and HTTPS-Everywhere are free Firefox add-ons that force the browser to use encryption on popular websites that usually aren’t encrypted. They don’t protect you on all websites – look for https in the URL to know a site is secure.

Know How Digital Signature Works

Digital signatures are a way to verify that an email message is really from the person who supposedly sent it and that it hasn’t been changed.

What is a digital signature?

There are different types of digital signatures; this tip focuses on digital signatures for email messages. You may have received emails that have a block of letters and numbers at the bottom of the message. Although it may look like useless text or some kind of error, this information is actually a digital signature. To generate a signature, a mathematical algorithm is used to combine the information in a key with the information in the message. The result is a random-looking string of letters and numbers.

Why would you use one?

Because it is so easy for attackers and viruses to “spoof” email addresses, it is sometimes difficult to identify legitimate messages. Authenticity may be especially important for business correspondence—if you are relying on someone to provide or verify information, you want to be sure that the information is coming from the correct source. A signed message also indicates that changes have not been made to the content since it was sent; any changes would cause the signature to break.

How does it work?

Before you can understand how a digital signature works, there are some terms you should know:

• Keys – Keys are used to create digital signatures. For every signature, there is a public key and a private key.
  • Private key – The private key is the portion of the key you use to actually sign an email message. The private key is protected by a password, and you should never give your private key to anyone.
  • Public key – The public key is the portion of the key that is available to other people. Whether you upload it to a public key ring or send it to someone, this is the key other people can use to check your signature. A list of other people who have signed your key is also included with your public key. You will only be able to see their identities if you already have their public keys on your key ring.
• Key ring – A key ring contains public keys. You have a key ring that contains the keys of people who have sent you their keys or whose keys you have gotten from a public key server. A public key server contains keys of people who have chosen to upload their keys.
• Fingerprint – When confirming a key, you will actually be confirming the unique series of letters and numbers that comprise the fingerprint of the key. The fingerprint is a different series of letters and numbers than the chunk of information that appears at the bottom of a signed email message.
• Key certificates – When you select a key on a key ring, you will usually see the key certificate, which contains information about the key, such as the key owner, the date the key was created, and the date the key will expire.
• “Web of trust” – When someone signs your key, they are confirming that the key actually belongs to you. The more signatures you collect, the stronger your key becomes. If someone sees that your key has been signed by other people that he or she trusts, he or she is more inclined to trust your key. Note: Just because someone else has trusted a key or you find it on a public key ring does not mean you should automatically trust it. You should always verify the fingerprint yourself.

The process for creating, obtaining, and using keys is fairly straightforward:

1. Generate a key using software such as PGP, which stands for Pretty Good Privacy, or GnuPG, which stands for GNU Privacy Guard.
2. Increase the authenticity of your key by having your key signed by co-workers or other associates who also have keys. In the process of signing your key, they will confirm that the fingerprint on the key you sent them belongs to you. By doing this, they verify your identity and indicate trust in your key.
3. Upload your signed key to a public key ring so that if someone gets a message with your signature, they can verify the digital signature.
4. Digitally sign your outgoing email messages. Most email clients have a feature to easily add your digital signature to your message.

There are a variety of mechanisms for creating digital signatures, and these mechanisms may operate differently. For example, S/MIME does not add a visible block of letters and numbers within the message, and its digital signatures are verified indirectly using a certificate authority instead of directly with other users in a web of trust. You may just see an icon or note on the message that the signature has been verified. If you get an error about a digital signature, try to contact the sender through a phone call or a separate email address that you know is valid to verify the authenticity of the message.

How to install- uninstall Windows 8

Microsoft has released beta version of Windows 8 for developers to test and discover the features.

you can download the beta version from this link : windows 8 developer preview

This site is having two type of ISO, one is for developers with including developer kit and another version is without developer kit. You can download either 32bit or 64bit version as per your PC hardware. It is suggested that you install 64bit of windows 8 if you already having 64bit version of Windows 7/VISTA/XP so that you can dual boot your PC from boot loader(MBR).

You should also required a free partition to install windows 8 over it. If you are not having any partition you can make a new one by using windows disk management utility to shrink your existing windows partition(c: drive).

Now burn the downloaded ISO over a writable media(DVD) and boot from DVD , if your computer is not set to default booting drive as cd , you can change it by your BIOS settings.

After booting from DVD choose to install as custom and choose the destination drive that you create to install windows 8.  when installation finished you will found dual boot mode with windows 8 with earlier version of windows(7/VISTA/XP).

Now enjoy windows 8 for free for one year from the date of installation. But remember that this is a beta version not a stable and final so use this only for testing purpose.

If you are not happy and want to uninstall windows 8 completely then follow the tips given below to avoid any problem and without loosing your existing windows data or settings:

1. boot from windows 7 or earlier version that you have in your PC

2. Now download and install easybcd from here, this is a very small and powerful software to edit your MBR(a file that is having details of bootloader).

3. In your easybcd goto  add new entry and add windows 8 also go to bcd deployment and click on write mbr, now in mbr windows 8 has been added to your boot menu.

4. Now you can boot either from windows 8 boot menu to windows 7 or earlier or you can boot from windows 7 or earlier to windows 8 vice versa.

5. when you want to uninstall windows 8 , simply boot with windows 7 or earlier version you have and go to easybcd and click on edit boot menu tab now select windows 7 as default and delete windows 8 entry then save . once check by rebooting if everything fine then using disk management utility or by simply right click on windows 8 partition and format this partition. now your PC is as like as it before.

6. If using easybcd you are not not able to delete your windows 8 entry then try msconfig type in run command msconfing and enter , then go to boot tab and delete windows 8 entry.

7. Now reboot and and check the boot-loader, If your PC failed to reboot from HDD after above changes you can also use your windows installation dvd to repair your start-up problem.

Discover Android 4.0 – Ice Cream Sandwitch

Android 4.0 (Ice Cream Sandwich) is the latest version of the Android platform for phones, tablets, and more. It builds on the things people love most about Android — easy multitasking, rich notifications, customizable home screens, resizable widgets, and deep interactivity — and adds powerful new ways of communicating and sharing.

Simple, Beautiful, Useful

Refined, evolved UI

Focused on bringing the power of Android to the surface, Android 4.0 makes common actions more visible and lets you navigate with simple, intuitive gestures. Refined animations and feedback throughout the system make interactions engaging and interesting. An entirely new typeface optimized for high-resolution screens improves readability and brings a polished, modern feel to the user interface.

Virtual buttons in the System Bar let you navigate instantly to Back, Home, and Recent Apps. The System Bar and virtual buttons are present across all apps, but can be dimmed by applications for full-screen viewing. You can access each application’s contextual options in the Action Bar, displayed at the top (and sometimes also at the bottom) of the screen.

Multitasking is a key strength of Android and it’s made even easier and more visual on Android 4.0. The Recent Apps button lets you jump instantly from one task to another using the list in the System Bar. The list pops up to show thumbnail images of apps used recently — tapping a thumbnail switches to the app.

The Recent Apps list makes multitasking simple.

Jump to the camera or see notifications without unlocking.

For incoming calls, you can respond instantly by text.

Rich and interactive notifications let you keep in constant touch with incoming messages, play music tracks, see real-time updates from apps, and much more. On smaller-screen devices, notifications appear at the top of the screen, while on larger-screen devices they appear in the System Bar.

Home screen folders and favorites tray

New home screen folders offer a new way for you to group your apps and shortcuts logically, just by dragging one onto another. Also, in All Apps launcher, you can now simply drag an app to get information about it or immediately uninstall it, or disable a pre-installed app.

The All Apps launcher (left) and resizable widgets (right) give you apps and rich content from the home screen.

On smaller-screen devices, the home screen now includes a customizable favorites tray visible from all home screens. You can drag apps, shortcuts, folders, and other priority items in or out of the favorites tray for instant access from any home screen.

Resizable widgets

Home screens in Android 4.0 are designed to be content-rich and customizable. You can do much more than add shortcuts — you can embed live application content directly through interactive widgets. Widgets let you check email, flip through a calendar, play music, check social streams, and more — right from the home screen, without having to launch apps. Widgets are resizable, so you can expand them to show more content or shrink them to save space.

New lock screen actions

The lock screens now let you do more without unlocking. From the slide lock screen, you can jump directly to the camera for a picture or pull down the notifications window to check for messages. When listening to music, you can even manage music tracks and see album art.

Quick responses for incoming calls

When an incoming call arrives, you can now quickly respond by text message, without needing to pick up the call or unlock the device. On the incoming call screen, you simply slide a control to see a list of text responses and then tap to send and end the call. You can add your own responses and manage the list from the Settings app.

Swipe to dismiss notifications, tasks, and browser tabs

Android 4.0 makes managing notifications, recent apps, and browser tabs even easier. You can now dismiss individual notifications, apps from the Recent Apps list, and browser tabs with a simple swipe of a finger.

A spell-checker lets you find errors and fix them faster.

A powerful voice input engine lets you dictate continuously.

Improved text input and spell-checking

The soft keyboard in Android 4.0 makes text input even faster and more accurate. Error correction and word suggestion are improved through a new set of default dictionaries and more accurate heuristics for handling cases such as double-typed characters, skipped letters, and omitted spaces. Word suggestion is also improved and the suggestion strip is simplified to show only three words at a time.

To fix misspelled words more easily, Android 4.0 adds a spell-checker that locates and underlines errors and suggests replacement words. With one tap, you can choose from multiple spelling suggestions, delete a word, or add it to the dictionary. You can even tap to see replacement suggestions for words that are spelled correctly. For specialized features or additional languages, you can now download and install third-party dictionaries, spell-checkers, and other text services.

Powerful voice input engine

Android 4.0 introduces a powerful new voice input engine that offers a continuous “open microphone” experience and streaming voice recognition. The new voice input engine lets you dictate the text you want, for as long as you want, using the language you want. You can speak continously for a prolonged time, even pausing for intervals if needed, and dictate punctuation to create correct sentences. As the voice input engine enters text, it underlines possible dictation errors in gray. After dictating, you can tap the underlined words to quickly replace them from a list of suggestions.

Data usage controls let you monitor total usage by network type and application and then set limits if needed.

Control over network data

Mobile devices can make extensive use of network data for streaming content, synchronizing data, downloading apps, and more. To meet the needs of you with tiered or metered data plans, Android 4.0 adds new controls for managing network data usage.

In the Settings app, colorful charts show the total data usage on each network type (mobile or Wi-Fi), as well as amount of data used by each running application. Based on your data plan, you can optionally set warning levels or hard limits on data usage or disable mobile data altogether. You can also manage the background data used by individual applications as needed.

Designed for accessibility

A variety of new features greatly enhance the accessibility of Android 4.0 for blind or visually impaired users. Most important is a new explore-by-touch mode that lets you navigate without having to see the screen. Touching the screen once triggers audible feedback that identifies the UI component below; a second touch in the same component activates it with a full touch event. The new mode is especially important to support users on new devices that use virtual buttons in the System Bar, rather than dedicated hardware buttons or trackballs. Also, standard apps are updated to offer an improved accessibility experience. The Browser supports a script-based screen reader for reading favorite web content and navigating sites. For improved readability, you can also increase the default font size used across the system.

The accessibility experience begins at first setup — a simple touch gesture during setup (clockwise square from upper left) activates all accessibility features and loads a setup tutorial. Once accessibility features are active, everything visible on the screen can be spoken aloud by the standard screen reader.

Contacts and profiles are integrated across apps and social networks, for a consistent, personal experience everywhere — from incoming calls to emails.

Communication and sharing

People and profiles

Throughout the system, your social groups, profiles, and contacts are linked together and integrated for easy accessibility. At the center is a new People app that offers richer profile information, including a large profile picture, phone numbers, addresses and accounts, status updates, events, and a new button for connecting on integrated social networks.

Your contact information is stored in a new “Me” profile, allowing easier sharing with apps and people. All of your integrated contacts are displayed in an easy to manage list, including controls over which contacts are shown from any integrated account or social network. Wherever you navigate across the system, tapping a profile photo displays Quick Contacts, with large profile pictures, shortcuts to phone numbers, text messaging, and more.

Unified calendar, visual voicemail

To help organize appointments and events, an updated Calendar app brings together personal, work, school, and social agendas. With user permission, other applications can contribute events to the calendar and manage reminders, for an integrated view across multiple calendar providers. The app is redesigned to let you manage events more easily. Calendars are color-coded and you can swipe left or right to change dates and pinch to zoom in or out agendas.

In the phone app, a new visual voicemail features integrates incoming messages, voice transcriptions, and audio files from one or more providers. Third-party applications can integrate with the Phone app to add your own voice messages, transcriptions, and more to the visual voicemail inbox.

Capture the picture you want, edit, and share instantly.

Rich and versatile camera capabilities

The Camera app includes many new features that let you capture special moments with great photos and videos. After capturing images, you can edit and share them easily with friends.

When taking pictures, continuous focus, zero shutter lag exposure, and decreased shot-to-shot speed help capture clear, precise images. Stabilized image zoom lets you compose photos and video in the way you want, including while video is recording. For new flexibility and convenience while shooting video, you can now take snapshots at full video resolution just by tapping the screen as video continues to record.

To make it easier to take great pictures of people, built-in face detection locates faces in the frame and automatically sets focus. For more control, you can tap to focus anywhere in the preview image.

For capturing larger scenes, the Camera introduces a single-motion panorama mode. In this mode, you start an exposure and then slowly turn the Camera to encompass as wide a perspective as needed. The Camera assembles the full range of continuous imagery into a single panoramic photo.

After taking a picture or video, you can quickly share it by email, text message, bluetooth, social networks, and more, just by tapping the thumbnail in the camera controls.

A Photo Gallery widget on the home screen.

Redesigned Gallery app with photo editor

The Gallery app now makes it easier to manage, show, and share photos and videos. For managing collections, a redesigned album layout shows many more albums and offers larger thumbnails. There are many ways to sort albums, including by time, location, people, and tags. To help pictures look their best, the Gallery now includes a powerful photo editor. You can crop and rotate pictures, set levels, remove red eyes, add effects, and much more. After retouching, you can select one or multiple pictures or videos to share instantly over email, text messaging, bluetooth, social networks, or other apps.

An improved Picture Gallery widget lets you look at pictures directly on the home screen. The widget can display pictures from a selected album, shuffle pictures from all albums, or show a single image. After adding the widget to the home screen, you can flick through the photo stacks to locate the image you want, then tap to load it in Gallery.

Live Effects let you change backgrounds and use Silly Faces during video.

Live Effects for transforming video

Live Effects is a collection of graphical transformations that add interest and fun to videos captured in the Camera app. For example, you can change the background behind them to any stock or custom image, for just the right setting when shooting video. Also available for video is Silly Faces, a set of morphing effects that use state-of-the-art face recognition and GPU filters to transform facial features. For example, you can use effects such as small eyes, big mouth, big nose, face squeeze, and more. Outside of the Camera app, Live Effects is available during video chat in the Google Talk app.

Snapping a screenshot.

Sharing with screenshots

You can now share what’s on your screens more easily by taking screenshots. Hardware buttons let them snap a screenshot and store it locally. Afterward, you can view, edit, and share the screen shot in Gallery or a similar app.

Cloud-connected experience

Android has always been cloud-connected, letting you browse the web and sync photos, apps, games, email, and contacts — wherever you are and across all of your devices. Android 4.0 adds new browsing and email capabilities to let you take even more with them and keep communication organized.

The Browser tabs menu (left) lets you quickly switch browser tabs. The options menu (right) gives you new ways to manage your browsing experience.

Benchmark comparisons of Android Browser.

Powerful web browsing

The Android Browser offers an experience that’s as rich and convenient as a desktop browser. It lets you instantly sync and manage Google Chrome bookmarks from all of your accounts, jump to your favorite content faster, and even save it for reading later in case there’s no network available.

To get the most out of web content, you can now request full desktop versions of web sites, rather than their mobile versions. You can set your preference for web sites separately for each browser tab. For longer content, you can save a copy for offline reading. To find and open saved pages, you can browse a visual list that’s included with browser bookmarks and history. For better readability and accessibility, you can increase the browser’s zoom levels and override the system default text sizes.

Across all types of content, the Android Browser offers dramatically improved page rendering performance through updated versions of the WebKit core and the V8 Crankshaft compilation engine for JavaScript. In benchmarks run on a Nexus S device, the Android 4.0 browser showed an improvement of nearly 220% over the Android 2.3 browser in the V8 Benchmark Suite and more than 35% in the SunSpider 9.1 JavaScript Benchmark. When run on a Galaxy Nexus device, the Android 4.0 browser showed improvement of nearly 550% in the V8 benchmark and nearly 70% in the SunSpider benchmark.

Improved email

In Android 4.0, email is easier to send, read, and manage. For composing email, improved auto-completion of recipients helps with finding and adding frequent contacts more quickly. For easier input of frequent text, you can now create quick responses and store them in the app, then enter them from a convenient menu when composing. When replying to a message, you can now toggle the message to Reply All and Forward without changing screens.

For easier browsing across accounts and labels, the app adds an integrated menu of accounts and recent labels. To help you locate and organize IMAP and Exchange email, the Email app now supports nested mail subfolders, each with synchronization rules. You can also search across folders on the server, for faster results.

For enterprises, the Email app supports EAS v14. It supports EAS certificate authentication, provides ABQ strings for device type and mode, and allows automatic sync to be disabled while roaming. Administrators can also limit attachment size or disable attachments.

For keeping track of incoming email more easily, a resizable Email widget lets you flick through recent email right from the home screen, then jump into the Email app to compose or reply.

Android Beam lets you share what you are using with a single tap.

Innovation

Android is continuously driving innovation forward, pushing the boundaries of communication and sharing with new capabilities and interactions.

Android Beam for NFC-based sharing

Android Beam is an innovative, convenient feature for sharing across two NFC-enabled devices, It lets people instantly exchange favorite apps, contacts, music, videos — almost anything. It’s incredibly simple and convenient to use — there’s no menu to open, application to launch, or pairing needed. Just touch one Android-powered phone to another, then tap to send.

For sharing apps, Android Beam pushes a link to the app’s details page in Android Market. On the other device, the Market app launches and loads the details page, for easy downloading of the app. Individual apps can build on Android Beam to add other types of interactions, such as passing game scores, initiating a multiplayer game or chat, and more.

Face recognition lets you unlock your phone with your face.

Face Unlock

Android 4.0 introduces a completely new approach to securing a device, making each person’s device even more personal — Face Unlock is a new screen-lock option that lets you unlock your device with your face. It takes advantage of the device front-facing camera and state-of-the-art facial recognition technology to register a face during setup and then to recognize it again when unlocking the device. Just hold your device in front of your face to unlock, or use a backup PIN or pattern.

Wi-Fi Direct and Bluetooth HDP

Support for Wi-Fi Direct lets you connect directly to nearby peer devices over Wi-Fi, for more reliable, higher-speed communication. No internet connection or tethering is needed. Through third-party apps, you can connect to compatible devices to take advantage of new features such as instant sharing of files, photos, or other media; streaming video or audio from another device; or connecting to compatible printers or other devices.

Android 4.0 also introduces built-in support for connecting to Bluetooth Health Device Profile (HDP) devices. With support from third-party apps, you can connect to wireless medical devices and sensors in hospitals, fitness centers, homes, and elsewhere.

Resource : Android.com