Divisibility Rule

Divisibility by 2 Rule  

Rule: Almost everyone is familiar with this rule which states that any even number can be divided by 2. Even numbers are multiples of 2. A number is even if ends in 0,2,4,6, or 8.

Divisibility by 3 Rule  

Rule: A number is divisible by 3 if the sum of its digits is divisible by 3.

Divisibility by 4 Rule 

Rule: A number is divisible by 4 if the number's  last two digits are divisible by 4.

Divisibility by 5 Rule 

Rule: A number is divisible by 5 if the its last digit is a 0 or 5.

Divisibility by 8 Rule

Rule: A number passes the test for 8 if the last three digits form a number is divisible 8.

Divisibility by 9 Rule  

Rule: A number is divisible by 9 if the sum of the digits are evenly divisible 9.

Divisibility by 10 Rule  

Rule: A number passes the test for 10 if its final digit is 0.

What Is Dielectric Testing?

Dielectric testing is a evaluation process performed by applying a voltage to an electrical component that exceeds its normal operating voltage. The purpose of the test is to determine if a component’s insulation is adequate enough to protect the user from electric shock. This testing procedure is typically performed on electrical components, such as circuit boards, appliances, cables, transformers, and electric motors. The manufacturer of an electrical component typically conducts the testing at the end of the production process, using a special device known as a dielectric tester.
Almost all electrical components leak a certain amount of electrical current due to a variety of different factors. This very small amount of current is considered to be safe for users, but under certain conditions, the insulating materials or mechanisms can breakdown and allow dangerous amounts to come into contact with the user. This type of insulation failure can sometimes cause serious injury or death. Dielectric testing is necessary to ensure that the insulating mechanism of an electrical component will withstand voltage variations under normal operating conditions.
The most common type of testing is the dielectric breakdown test. In this procedure, a high voltage electrical current is applied to the component. The dielectric tester monitors the amount of current leakage during the test to determine if the insulation has failed. The high voltage current continues to be applied to the device until the insulation fails or the time limit of the procedure has been reached. If the insulating mechanism does not fail, the product is usually considered to be safe for use. Electrical components that fail during dielectric testing are typically redesigned in order to meet safety requirements.
In addition to the dielectric breakdown test, a procedure known as a dielectric withstand test is also conducted to determine if defects have occurred during the manufacturing process. Electrical components sometimes contain small flaws, such as gaps or spaces that can create an electrical short circuit during the normal operation of a device. Dirt, humidity, environmental contaminates, and vibration can combine to produce an electrical shock hazard if these manufacturing flaws go undetected prior to consumer use. In this procedure, electrical current is supplied to the component at normal operating voltage. A dielectric tester is attached to the component to monitor the amount of current leakage present. If the leakage levels are within an acceptable range, the component is approved for use.

Source:- www.wisegeek.org 

What is power factor?

Power factor is the relationship between working (active) power and total power consumed (apparent power). Essentially, power factor is a measurement of how effectively electrical power is being used. The higher the power factor, the more effectively electrical power is being used. A distribution system's operating power is composed of two parts: Active (working) power and reactive (non-working magnetizing) power. The ACTIVE power performs the useful work - the REACTIVE power does not. It's only function is to develop magnetic fields required by inductive devices.

Why improve low power factor?

Low power factor means poor electrical efficiency. The lower the power factor, the higher the apparent power drawn from the distribution network.
When low power factor is not corrected, the utility must provide the nonworking reactive power in addition to the working active power. This results in the use of larger generators, transformers, bus bars, wires, and other distribution system devices that otherwise would not be necessary.
As the utility's capital expenditures and operating costs are going to be higher, they are going to pass these higher expenses to industrial users in the form of power factor penalties and higher utility bills.

 

 

ABB's Power Factor Correction Capacitors Solve the Problem

Solve low power factor problems by adding power factor correction capacitors to your electrical network. As illustrated below, power factor correction capacitors work as reactive current generators "providing" needed reactive power (kvar) to the power supply. By supplying their own source of reactive power, the industrial user frees the utility from having to supply it; therefore, the total amount of apparent power (kVA) supplied by the utility will be less. Power factor correction capacitors reduce the total current drawn from the distribution system and subsequently increase system capacity.

Who can benefit?

Many industrial and commercial applications can benefit from improving power factor levels. These include: manufacturers, hospitals, shopping malls, office building & institutions, pulp & paper mills, saw mills, textile mills, printing plants, Dlastic manufacturers. etc.

How much can be saved?

In the following example, if power factor correction is applied to the electrical network, increasing power factor to 90%, the potential annual savings on utility bills would be $4,322.23, or an average of $360 per month, a savings of up to 15%!

what is the role of reactive power in power generation?why we have maintain it.

 Electrical machines work on the principle of conversion of
electromagnetic energy.A part of input energy is consumed 
for creating and maintaining the magneticfield.This part of
the input energy cannot be converted into active energy and
is returned to the electrical network on removal of the
magnetic field. This power is known as “reactive” power Q.
The Q Power flows back and forth, causing 90º Out of phase
shift between the current and voltage waveform.This
Reactive Power has one half of the Power In the positive
area and the other half in the negative area.
Unlike true power, reactive power is not useful power
because it is stored in the circuit itself.
This power is stored by
1)Inductors,
Because they expand and collapse their magnetic
fields in an attempt to keep current constant,
2) Capacitors, Because they charge and discharge in an
attempt to keep voltage constant. 

Calculator and E+ meaning

Calculators and e+ The e stands for Exponent, which means the number of tens you multiply a number by. For example, if I square 123456789, I get 1.524157875019e+16, which means that the answer is 1.524157875019 times 10 raised to the sixteenth power (that is, multiplied by 10 sixteen times). To write it as a regular number, you can just move the decimal point to the right sixteen places, since multiplying by ten moves the decimal point one place to the right: 1.524157875019e+16 = 15,241,578,750,190,000 That's over 15 quadrillion. You can also have a negative exponent, which means you have to move the decimal point to the left. For example, if I divide 1 by 123456789, I get: 8.10000007371e-9 = 0.00000000810000007371 In both cases, you can see that the reason for using the "e" notation is to be able to show a number that would have too many digits to display if they wrote it all out. If you are interested in more about this, you might do a search in the Dr. Math archives for the words scientific notation . - Doctor Peterson, The Math Forum

How to Set FreeFileSync Realtime Sync.exe to run automatically on Windows

1st thing you need to know how to create a batch job with FreeFileSync main program
go to Menu > Advanced> Create batch job
Configure the settings as you desired then save it to your desire folder, for this case i will
use dektop to save the batch job with a name "MyRealTimeSync.ffs_batch"
make sure that you enable thesilent modeand ignore all error
after you got the file navigate to FreeFileSync Installation Folder and execute
RealtimeSync.exe (Its a litle apps with red FreeFileSync icon)
Navigate to Menu > File> Load Configuration
Choose the *.ffs_batchfile you had created before

1st Method

Navigate to Control Panel> Task Schedulerthen click on Create Basic Task
Give a name for the Task whatever your wish
Select the "When I log on" button
Choose Start a program on Trigger tab
add a location of your batch file on add argumentsbox
if a warning box appear choose Yesand Finish

2nd Method

Create a shortcut on windows Startup folder then add type to the targettextbox with your
batch file location with quote
ex:"C:\Program Files\FreeFileSync\RealtimeSync.exe" "C:SyncJob.ffs_batch"
Now every time you Start your Windows You will had a Realtime Sync Running on the
background

SCR or Thyristor both are same

A silicon-controlled rectifier (or semiconductor-controlled rectifier) is a four-layer solid state current controlling device.

• ·         The name "silicon controlled rectifier" or SCR is General Electric's trade name for a type of thyristor.

The SCR was developed by a team of power engineers led by Robert N. Hall and commercialized by Frank W. "Bill" Gutzwiller in 1957.

Modes of operation

This device is generally used in switching applications. In the normal "off" state, the device restricts current to the leakage current. When the gate-to-cathode voltage exceeds a certain threshold, the device turns "on" and conducts current. The device will remain in the "on" state even after gate current is removed so long as current through the device remains above the holding current. Once current falls below the holding current for an appropriate period of time, the device will switch "off". If the gate is pulsed and the current through the device is below the latching current, the device will remain in the "off" state.

If the applied voltage increases rapidly enough, capacitive coupling may induce enough charge into the gate to trigger the device into the "on" state; this is referred to as "dv/dt triggering." This is usually prevented by limiting the rate of voltage rise across the device, perhaps by using a snubber. "dv/dt triggering" may not switch the SCR into full conduction rapidly, and the partially triggered SCR may dissipate more power than is usual, possibly harming the device.

SCRs can also be triggered by increasing the forward voltage beyond their rated breakdown voltage (also called as break over voltage), but again, this does not rapidly switch the entire device into conduction and so may be harmful so this mode of operation is also usually avoided. Also, the actual breakdown voltage may be substantially higher than the rated breakdown voltage, so the exact trigger point will vary from device to device.

Reverse Bias

SCR are available with or without reverse blocking capability. Reverse blocking capability adds to the forward voltage drop because of the need to have a long, low doped P1 region. Usually, the reverse blocking voltage rating and forward blocking voltage rating are the same. The typical application for reverse blocking SCR is in current source inverters.

SCR incapable of blocking reverse voltage are known as asymmetrical SCR, abbreviated ASCR. They typically have a reverse breakdown rating in the 10's of volts. ASCR are used where either a reverse conducting diode is applied in parallel (for example, in voltage source inverters) or where reverse voltage would never occur (for example, in switching power supplies or DC traction choppers).

Application of SCRs

SCRs are mainly used in devices where the control of high power, possibly coupled with high voltage, is demanded. Their operation makes them suitable for use in medium to high-voltage AC power control applications, such as lamp dimming, regulators and motor control.

99 ka pher

“The 99 Club”

Friends, you may like to go through this wonderful story which I am sure will make you think that why happiness which could have embraced us easily can eludeus at times due to our own behaviour / approach towards life . Please don't forget to leave your valuable comment once you finished reading for the benefit of not just me but for others too visiting this post

Regards,

———————-

Once upon a time, there lived a King who, despite his luxurious lifestyle, was neither happy nor content.

One day, the King came upon a servant who was singing "happily" while he worked. This fascinated the King; why was he, the Supreme Ruler of the Land, unhappy and gloomy, while a lowly servant had so much joy.

The King asked the servant, ‘ Why are you so happy?’

The man replied, "Your Majesty, I am nothing but a servant, but my family and I don’t need too much - just a roof over our heads and warm food to fill our tummies"

The king was not satisfied with that reply. Later in the day, he sought the advice of his most trusted advisor. After hearing the King’s woes and the servant’s story, the advisor said, "Your Majesty, I believe that the servant has not been made part of The 99 Club".

‘The 99 Club? And what exactly is that?’ the King inquired.

The advisor replied, "Your Majesty, to truly know what The 99 Club is, place 99 Gold coins in a bag and leave it at this servant’s doorstep".

So the king did like wise. When the servant saw the bag, he took it into his house. When he opened the bag, he let out a great shout of joy… So many gold coins.

He began to count them. After several counts, he was at last convinced that there were 99 coins. He wondered, ‘ "What could’ve happened to that last gold coin? Surely, no one would leave 99 coins!"

He looked everywhere he could, but that final coin was elusive. Finally, exhausted, he decided that he was going to have to work harder than ever to earn that gold coin and complete his collection.

From that day, the servant’s life was changed. He was overworked, horribly grumpy, and castigated his family for not helping him make that 100th gold coin. He stopped singing while he worked.

Witnessing this drastictransformation, the King was puzzled. When he sought his advisor’s help, the advisor said,"Your Majesty, the servant has now officially joined The 99 Club".

He continued, "The 99 Club is a name given to those people who have enough to be happy but are never contented, because they’re always yearning and striving for that extra 1 telling to themselves: ‘Let me get that one final thing and then I will be happy for life" .

We can be happy, even with very little in our lives, but the minute we’re given something bigger and better, we want even more! We lose our sleep, our happiness, we hurt the people around us; all these as a price for our growing needs and desires. That’s what joining "The 99 Club" is all about. 

******

 Source:-princecharming123

Buck–boost converter

 

The buck–boost converter is a type of DC-to-DC converter that has an output voltage magnitude that is either greater than or less than the input voltage magnitude.
Two different topologies are called buck–boost converter. Both of them can produce a range of output voltages, from an output voltage much larger (in absolute magnitude) than the input voltage, down to almost zero.

Conceptual overview

Like the buck and boost converters, the operation of the buck-boost is best understood in terms of the inductor's "reluctance" to allow rapid change in current. From the initial state in which nothing is charged and the switch is open, the current through the inductor is zero. When the switch is first closed, the blocking diode prevents current from flowing into the right hand side of the circuit, so it must all flow through the inductor. However, since the inductor doesn't like rapid current change, it will initially keep the current low by dropping most of the voltage provided by the source. Over time, the inductor will allow the current to slowly increase by decreasing its voltage drop. Also during this time, the inductor will store energy in the form of a magnetic field.
When the switch is then opened, the inductor will be cut off from the input voltage supply, so the current will tend to drop to zero. Again, the inductor will fight such an abrupt change in current. To do so, it must now act like a voltage source to the rest of the circuit, which it can do using the energy it stored while charging. Since current was previously flowing "down" the inductor, it will want to maintain this direction, and so the voltage that it provides will be inverted relative to input supply. During this time, the inductor will discharge through the load and the rest of the circuit, which will cause its voltage to decrease over time. Also during this time, the capacitor in parallel with the load will charge up to the voltage presented by the inductor.
When the switch is once again closed, the diode is forward biased by the input supply, cutting the load off from the left hand side of the circuit. During this time, the capacitor will discharge into the load, providing energy and voltage to it. By cycling the switch fast enough, the inductor can be allowed to charge and discharge only slightly in each cycle, maintaining a relatively steady voltage to the load. Similarly, the capacitor will only need to discharge slightly while the switch is open before it has a chance to recharge again while the switch is closed.
The voltage presented by the inductor to the load depends on how long the switch is opened and closed. When the switch is closed and the inductor is charging, the current through the inductor is ramping up linearly. The longer the switch is closed, the higher the current will get. When the switch is then opened, it is the end current that the inductor will try to maintain by acting like a voltage source. The higher this current is, the more voltage the inductor will need to provide in order to produce it. Thus, the longer the switch is closed during the on stage, the higher the output voltage will be.

Choosing an Inverter and Battery for Home

Choosing an Inverter and Battery for Home

By: mr_suresh |

Knowledge must be shared. So I thought of sharing my knowledge gained during research on inverters. I hope it will be useful for others to decide the right inverter quickly.
DIFFERENCE BETWEEN UPS AND INVERTER
Inverter is an electronic circuit for converting Direct Current to Alternating Current. They are used in a wide range of applications from small switched power supplies to large electric utility applications to transport bulk power (like Air Conditioners, Fridge, Mixie etc.)

A UPS typically includes the battery and battery charger in one stand alone unit, especially used for computer backups. UPS will effectively switch from utility power to its own power source almost instantaneously.
WAVES - SQUARE WAVE, SINE WAVE AND QUASI SINE WAVE
Square Wave Inverters
Simplest and least expensive in the market. Computers, televisions, induction motors, transformer loads and even light bulbs are not recommended to run on this waveform, because square wave has a high harmonic content.
Sine Wave Inverters
This is the correct waveform on which all electronic equipment, televisions, and computers are designed to run. They filter the output voltage well and recommended.
Quasi-Sine Wave Inverters
Indeed correct selection for running some types of motors and incandescent lighting and not fit for all types of equipments, hence it is not recommended.
CALCULATE YOUR POWER CONSUMPTION
This can be done by adding up the watts on the equipment specifications normally printed below or behind the equipments.

I selected 800 VA which delivers approximately 640 watts. Don’t select very high inverter than the requirement as it will consume more electricity and loss of power is also higher.
CHOOSING THE INVERTER
After calculating the consumption the next step is to select the Inverter VA.

The formula is
Watts / Power Factor = VA
For me it was
542 Watts / 0.8 Power Factor = 677 VA
(Power Factor: 0.8 for most of the UPS, incase of APC Inverters the power factor is 0.6, you can refer product manual or ask dealer for this info)

So the available VA’s in market are 500 VA, 800 VA, 1000 VA, 1400 VA and above. I selected 800 VA.

CHOOSING INVERTER BRAND
This was quite difficult. I selected few known brands in market like Luminous (widely advertised in 2004), Genus (OEM supplier for LG and Samsung), Su-Kam (From few years they are in the market, but most advertised), Hyundai (New, manufactured by Luminous under license from Hyundai Korea), Microtek (Addidas group) and APC (New to Home Inverter).

CHOOSING BATTERY SIZE
Batteries are available in various Amperes. You need to decide how much backup you require and decide on the amperes.
Here is the formula to calculate the backup
Load/Voltage x Backup hours = Amperes
In my case it was
542 Watts / 12 V x 3 hrs = 135 Ah
I selected 130 Ah Standard Furokawa battery for my home.

CHOOSING BATTERY
Battery is a backbone for any inverter. There are different types of battery available in the market.

Maintenance battery
These batteries requires maintenance every month. The distilled water needs to be filled every month.

Maintenance free battery
This comes with flat plate collectors and maintenance free. These batteries will have a life of 4 years.

Tubular batteries
Here the active material (lead oxide) is encapsulated in polyester tubes to prevent ‘Shedding’. The electrode geometry facilitates ‘cyclic’ deep discharges. They are recommended for back up power for UPS and Inverters where environmental conditions are tough and high ambient temperatures are common. These are capable of long hours of backup.