What is capacitor? How capacitor stores charge? How big is Farad?

Capacitor is used to store the energy but the process how capacitor stores energy will be discussed in this article. Capacitor is also known as condenser. It is used both in electrical and electronic circuits and they are available in smaller sizes from Picofarad to KVAr. Capacitors have wide applications in electrical systems such as for starting of single phase motors. Capacitors are also used for providing reactive power so as to improve power factor which will leads to lower electricity bill and lower burden on Generating station.

Capacitors are also used in :-

1.      Oscillation circuits

2.      They are used to smooth rectified AC Outputs.

3.      Radio receivers for tuning.

4.      Time delay circuits

5.      Electrical filters.

Units of capacitor are Farad. It is symbolized by Letter “F”. A Farad is defined as “the capacitance when a potential difference of one volt appears across the plates when charged with one coulomb.”

Capacitors used in day to day activity are Mircofarad i.e. 10<sup>-6

Capacitor Symbol:-</sup>

Capacitor symbols are as shown below:-

You Know how big is the Farad is?? 

Let’s have an idea how big size of plates are required to get a value of just one Farad with a reasonable plate separation of just say 1mm operating in a vacuum. If we rearranging the equation for capacitance above this would give us a plate area of:

 C= Q/V= permittivity, ( ε )X Area of plates

                            Distance between Plates

For air as dielectric medium Value of Permittivity is = 8.85pF/m 

Put the values into formula we get:-

A = (C)d ÷ 8.85pF/m = (1 x 0.001) ÷ 8.85×10^-12 = 112,994,350 m²

or 113 million m² which would be equivalent to a plate of more than 10 kilometres x 10 kilometres (over 6 miles) square. That Value is very huge and is practically not possible.

How Capacitor store Charge??

Two Parallel Plates form a capacitor. When capacitor is connected to DC supply then one side of plate is get positive charged and other get negative charges depending upon polarity of DC supply. I.e. how they store the charge i.e. store energy. If plates are kept on charge in air beyond a certain limit then plates will start getting discharged by spark getting produced due to excessive charge.To increase the amount of stored charge a dielectric medium i.e. a non conducting medium placed between plates. This medium also act as spark blocker .

Types of Dielectric Medium:-

§  Some of dielectric material used in commercial capacitors :-

1.      Paper

2.      Plastic film

3.      Mica

4.      Glass

5.      Ceramic

6.      Air.

The electrical energy is stored in the capacitor in the form of electrostatic field.

C = Q/V

Here
C = Capacitance in F
Q = Charge in Coulomb
V = Voltage applied across the capacitor in Volts

The capacitor current equation is given below
I = C.dV/dt
C =  Capacitance

dV/dt = Change in voltage across the capacitor
I is known as Displacement current. It is not the current flows through the capacitor.

There are so many types of capacitors available depending upon the type of insulation material used as dielectric for knowing about types of capacitors please visit link below:-

http://electrialstandards.blogspot.in/2015/05/types-of-capacitors.html

To know about series and Parallel operation of capacitor, Visit link:-
http://electrialstandards.blogspot.com/2015/05/capacitor-in-series-and-parallel.html

Net metering in Solar Systems; On Grid and Off Grid system in Solar Power

What is Net Metering?
Net metering is the concept  used in Solar Power where discoms will allow Individuals and corporate's to feed power generated from Solar or any means to their grid . A net metering meter will be installed by Power distribution company(DISCOM) which measures power fed to grid and accordingly consumer will be charged or paid back. Alternatively, the meter, having the feature of recording both the import and export values.

Solar PV Power Generation:

Sunlight is converted to electricity directly when made to fall on solar photovoltaic (SPV) modules. This electricity generated is used for lighting and various other purposes. 

Grid connected roof top solar PV system: 

In recent years solar PV systems became viable and attractive.  Available roof-top area on the buildings can also be used for setting up solar PV power plants which will leads to no expenses for land requirements for solar panels installations.

The electricity generated from SPV systems can also be fed to the distribution or transmission grid after conditioning to suit grid integration. There are two types of configurations available for connecting the solar power generated from the system.
(1) On grid
(2) Off grid

In On grid System power generated from solar panels is directly synchronized with existing power source of discom in such a way that solar power generated get consumed in systems and power cost get reduced by power generated by solar system. let's simplify the same with an example:- Suppose there is plant having Three phase 100 KW power requirements now the plant installed 5 KW three phase Solar power panels now in On grid system power generated from solar system is directly get reduced from total power requirement means there will be 95 KW requirement from DISCOM and user have to pay for 95 KW instead of 100 KW. This type of activity is most popularly used worldwide.

Now lets discuss Off Grid system. In off grid power generated from Solar panels is stored in batteries and later on used whenever there is requirement. e.g. in morning power is stored in Batteries and later on this stored power is used for lighting and other purposes by taking the help of Inverters.

Usually On grid System is most preferred as there is no requirement of Batteries . Also efficiency of On grid system is more then Off grid system.

How does it work?

Based on available roof area solar PV panels will be installed on the roof of the building. The output of the panels (DC electricity) connect to the power conditioning unit / inverter which converts DC to AC. The inverter output will be connected to the control panel or distribution board of the building to utilise the power. The inverter synchronises with grid and also with any backup power source to produce smooth power to power the loads with preference of consuming solar power first. If the solar power is more than the load requirement, the excess power is automatically fed to the grid. For larger capacity systems connection through step up transformer and switch yard may be required to feed the power to grid. Operation and Maintenance Requirements: There are no moving parts in the system and it requires only minimal attention. Depending upon the dust level, the system requires periodic cleaning.

Advantages:

The grid connected roof top solar PV system would fulfil the partial / full power needs of large scale buildings. The following are some of the benefits of roof top SPV systems:

· Generation of environmentally clean energy.

· Consumer becomes generator for his own electricity requirements.

· Reduction in electricity consumption from the grid.

 · Reduction in diesel consumption wherever DG backup is provided.

· Feeding excess power to the grid.

Implementation:

a) Implementation of net metering facility shall be made applicable for the consumers having 3-phase supply service connection.

b) Protection system including its switch gear has to be certified by concerned DE/MRT Operation. Further, harmonic suppressive device has to be installed by such SPV generator to suppress the harmonics injection as harmonics is more in case of solar plants where conversion of DC to AC is taking place (Islanding protection requirements are enclosed).

c) The SPV generator shall provide the indication of solar PV plant at the injection point for easy identification to the operating personnel.

d) The SPV generator needs to get statutory approvals from appropriate authority (CEIG) for the connected equipment including its solar panels.

e) The proposed generator shall submit the prescribed application to the concerned DE/Opn.

f) The net meter / meter to be used for arriving net energy shall have the specifications prescribed.

g) Concerned DE/Opn and DE/MRT will issue a technical feasibility certificate and witness the synchronization of SPV plant with distribution network.

h) 0.2 class accuracy, tri-vector based energy meter, non ABT having the MRI downloading facility along with related accessories shall have to be installed by the SPV generator as per the specifications of APTRANSCO/APDISCOMS.

Alternatively, DISCOM may provide the metering arrangement after receiving entire estimated cost from such generator.

i) SPV generator needs to provide an insurance coverage of Rs.5.00 lakhs per annum to meet the expenditure that may be aroused due to electrocution in the event of failure of connected protective and switch gear.

 j) Spot billing is to be arranged by concerned ADE/Opn as per the billing period. DISCOM shall arrange to develop suitable software and incorporate in the billing instrument for such billing. 

Maximum Power Point Tracking in Solar Power; MPPT in Solar Power, MPPT working

Maximum Power Point Tracking is most powerfull concept in the field of Solar power . Let’s study about what is Maximum Solar power point tracking and it’s applications in Solar power systems.

A MPPT is an electronic DC to DC converter that optimizes the midst of the solar array (PV panels), and the battery bank to get the optimum use of Solar power. 

Why There is Need of MPPT

Solar cells are clean source of Energy. Most Solar PV panels are built to give nominal output voltage of 12 volts. But Solar cells designed for 12V can give output from 16V to 18V.  Mostly batteries are charged from about 13.2 to 14.4 volts. Now Solar panels can give output voltage ranging from 16V to 18V but batteries can be charged upto 13.2-14.4V.

Now lets assume that we have a solar panel having Capacity of 150 watt.

The Solar power panel is rated at 8.52 amps at 17.6 volts. (8.52 amps X 17.6 volts = 150 watts).

 i.e. Solar panel will give output voltage of 17.6 Volts at 8.52A. But this is Solar power panel output voltage. 

But batteries can be charged upto maximum of 14.4 volts. Now if we assume that battery is get charged to 14V then output we get is  8.52 A X 14 volts = 119.56 Watts. Now you see that you have paid for 150W and what you get is approx. 120W means there will be loss of 30W every hour. Now what we get if battery is only get charged to 12V.

Output at 12V will be 8.52A X 12V= 102.24 W now loss will become even higher.

The panel is rated at 150 watts at full sunlight at a particular temperature. If temperature of the solar panel is high, you may not get 17.4 volts output. At higher temperatures output voltage of solar panel will get reduced to 16 volts.  

Now question arises why not we install 15V output Solar panels??
Solar panels have to work under worst conditions in some times at that time if output voltage will be 15V then there are chances that batteries doesn't get charged.

How MAXIMUM POWER POINT TRACKING System Works:-

Panel tracking - this is where the panels are vis--vis a mount that follows the sun. The most common are the Zomeworks and Wattsun. These optimize output by as well as the sun across the declare for maximum sunlight. Panel tracking system will give output power increase of 15% in winter and 35% increase in summers.  MPPT is just opposite of the Panel tracking in case of seasonal variations i.e. MPPT will increase power output in winters then in summers. 

Since panel temperatures are much lower in winter, they will give more power. In winter more power needed from solar panels due to shorter days.

Maximum Power Point Tracking is and electronic system. The controller looks at the output of the panels, and compares it to the battery voltage. It as well as figures out what is the best capacity that the panel can to achievement the battery. It takes this and converts it to best voltage to profit maximum AMPS into the battery. Most take in hand looking MPPT's are concerning 93-97% efficient in the conversion. You typically acquire a 20 to 45% gift be in in winter and 10-15% in summer. Actual be in can change widely depending weather, temperature, battery verify of proceedings, and late growth factors.

Grid tie systems are becoming more popular as the price of solar drops and electric rates go occurring. There are several brands of grid-tie by yourself (that is, no battery) inverters comprehensible. All of these have built in MPPT. Efficiency is almost 94% to 97% for the MPPT conversion as regards the order of those.

How Maximum Power Point Tracking works

Here is where the optimization, or maximum adroitness lessening tracking comes in. Assume your battery is low, at 12 volts. A MPPT takes that 17.6 volts at 8.52 amps and converts it also to, consequently that what the battery gets is now 13.04 amps at 12 volts. Now you yet have in this area 156.5 watts, and everyone is glad.

Ideally, for 100% gift conversion you would acquire on the subject of 13.04 amps at 11.5 volts, but you have to feed the battery a far ahead voltage to force the amps in. And this is a simplified checking account - in actual fact the output of the MPPT row controller might adjust forever to become accustomed for getting the maximum amps into the battery.

 Typical Power Curve of a Solar Electric PanelOn the left is a screen shot from the Maui Solar Software "PV-Design Pro" computer program (click upon describe for full size image). If you see at the green extraction, you will see that it has a gifted pinnacle at the upper right - that represents the maximum doer twist. What an MPPT controller does is "see" for that alter mitigation, furthermore does the voltage/current conversion to have an effect on it to exactly what the battery needs. In authentic animatronics, that summit moves as regards for ever and a day behind changes in light conditions and weather.

A MPPT tracks the maximum expertise narrowing, which is going to be oscillate from the STC (Standard Test Conditions) rating asleep not far off from all situations. Under the whole icy conditions a 120 watt panel is actually gifted of putting gone more 130+ watts because the knack output goes taking place as panel temperature goes in addition to to - but if you don't have some exaggeration of tracking that carrying out narrowing, you are going to lose it. On the subsidiary hand numb each and every one hot conditions, the execution drops - you lose facility as the temperature goes happening. That is why you do less reach in summer.

MPPT's are most energetic out cold these conditions:

Winter, and/or cloudy or confusing days - in imitation of the supplementary realization is needed the most.

Cold weather - solar panels perform augmented at chilly temperatures, but without a MPPT you are losing most of that. Cold weather is maybe in winter - the era as soon as sun hours are low and you compulsion the behave to recharge batteries the most.

Low battery dispute - the degrade the fall in along in the middle of of charge in your battery, the more current a MPPT puts into them - again gone the totaling triumph is needed the most. You can have both of these conditions at the joined period.

Long wire runs - If you are charging a 12 volt battery, and your panels are 100 feet away, the voltage drop and faculty loss can be considerable unless you use utterly large wire. That can be certainly costly. But if you have four 12 volt panels wired in series for 48 volts, the proficiency loss is much less, and the controller will convert that high voltage to 12 volts at the battery. That with means that if you have a high voltage panel setup feeding the controller, you can use much smaller wire.

Ok, suitably now lead to the original investigate - What is a MPPT?

How a Maximum Power Point Tracker Works:

The Power mitigation tracker is a tall frequency DC to DC converter. They admit the DC input from the solar panels, involve it to tall frequency AC, and convert it urge around furthermore to to a every second DC voltage and current to exactly harmonize the panels to the batteries. MPPT's conduct yourself at the entire tall audio frequencies, usually in the 20-80 kHz range. The advantage of tall frequency circuits is that they can be expected past every tall efficiency transformers and little components. The design of tall frequency circuits can be altogether tricky because the problems taking into account portions of the circuit "broadcasting" just furthermore a radio transmitter and causing radio and TV interference. Noise coldness and suppression becomes totally important.

There are a few non-digital (that is, linear) MPPT's charge controls on the subject of. These are much easier and cheaper to construct and design than the digital ones. They make a purchase of add together efficiency somewhat, but overall the efficiency can modify a lot - and we have seen a few lose their "tracking reduction" and actually buy your hands on worse. That can happen occasionally if a cloud passed on summit of the panel - the linear circuit searches for the adjacent best want, but subsequently gets too far out upon the deep decline to locate it in imitation of more when the sun comes out. Thankfully, not many of these as regards a new.

The power ambition tracker (and all DC to DC converters) operates by taking the DC input current, changing it to AC, paperwork through a transformer (usually a toroid, a doughnut looking transformer), and later rectifying it consent to help to to DC, followed by the output regulator. In most DC to DC converters, this is strictly an electronic process - no genuine smarts are working except for some regulation of the output voltage. Charge controllers for solar panels mannerism a lot more smarts as animate and temperature conditions rotate constantly every one of hours of day long, and battery voltage changes.

Smart power trackers

All recent models of digital MPPT controllers understandable are microprocessor controlled. They know bearing in mind to footnote yourself the output that it is creature sent to the battery, and they actually shut all along for a few microseconds and "heavens" at the solar panel and battery and make any needed adjustments. Although not in fact auxiliary (the Australian company AERL had some as in front as 1985), it has been unaided recently that electronic microprocessors have become cheap plenty to be cost operating in smaller systems (less than 1 KW of panel). MPPT charge controls are now manufactured by several companies, such as Outback Power, Xantrex XW-SCC, Blue Sky Energy, Apollo Solar, Midnite Solar, Morningstar and a few others.

To know about Net metering concept in solar System visit link:-http://electrialstandards.blogspot.in/2015/05/net-metering-in-solar-systems.html

Capacitor in Series and Parallel; Parallel Capacitors; Series Capacitors

We have seen that in the resistances in the case of a series connection their ohmic value increases, while in the case of a parallel connection decreases.

To know about series and Parallel connection in case of resistor please visit:-
http://electrialstandards.blogspot.in/2014/12/resistance-in-series-and-parallel.html

In capacitors is the exact opposite:-

Series connections of capacitors:-
A series of two capacitors will reduce their net capacitance which is similar to if distance between capacitor plates is increased, but working voltage will increase. In series connections charge stored by each capacitor is same. If we apply a voltage source to series connected capacitors than current flow will have only one path which will leads to same voltage across each capacitor.

Parallel Connections of Capacitors
In the case of a parallel connection the capacitors will have a higher capacity which is similar to as if they increased the size of the two plates, remain unchanged by their working voltage.

So let's see how they are calculated these two aspects will arise .

Capacitors in series: 
the value of the capacity that we will get if we will connect two capacitors in series will always be less than the capacity smaller. For example, if C1 had a capacity of 100 nF and C2 of 10nF, the final capacity will be certainly lower than 10nF.

The formula to derive the final capacity of a series is: (C1xC2) :( C1 + C2), in consequence Ctot = (100x10) :( 100 + 10) = 9.09nF.
If for example in our circuit there were n capacitors, the formula to derive the total capacity is transformed into: 1: 1 + C1: C2 + ... 1: RCN;
This is a formula obtained only to speed up operations in the design phase.



Capacitors in parallel:
The value that will get in the case of a parallel connection, will always be greater than each individual capacitive value. It 'easy to understand why if we keep this formula: Ctot = C3 + C4, therefore 100 + 10 = 110nF. Accordingly, to derive the total capacity of n condenzatori it will use the formula: C3 + C4 + ... Cn.

SI prefixes of capacitive values:

picofarad
microfarads
nanofarad

picofarad: 1,000 = nanofarad
picofarad: 1,000,000 = microfarads

nanofarad: = 1.000 microfarads
nanofarad x 1,000 = picofarad

x = 1.000 microfarads nanofarad
microfarads x 1,000,000 = picofarad

Note1: the formulas described above are valid for all types of capacitors, even if for the electrolytic must respect their polarities. In the case of series connection the positive pole must be connected with the negative pole of the second capacitor, while in the case of a parallel connection, the two positive poles must be connected together, same thing for the negative poles.

Note 2: in the capacitors is very important to the working voltage (is always printed on its wrapping after the capacity). For example, if collaghiamo a capacitor of 16V 100mF the heads of a voltage of 24V, it will damage in a matter of seconds; It is always better to choose a capacitor voltage higher than the required, in this case one from 100mF 35V would do fine.

Electrical Power in Series and Parallel

http://electrialstandards.blogspot.in/2014/12/electrical-power-in-series-and-parallel.html

Power factor Improvement formula; Additional KVAR required for Power factor improvment.

Every industry monitor its power factor so that they will not pay for reactive power at lower factor. It become very important to know what additional capacitor bank required for improvement of power factor. Every industry consists of inductive load such as lights and motors which usually have power factor in the range to 0.8 to 0.85. So power factor improvement is of prime importance as if they kept running their system at same power they suffer loss of 20 to 15%. As if they keep power factor at 1 they will not have pay any additional charges at lower power factor.

So let’s calculate what additional capacitor bank needed for power factor improvement. Let’s take an example that system is running at 0.8 power factor and inductive load is 200 KW what additional capacitor bank required for improvement of power factor from 0.8 to 1.

KVAR Required = KW X [tan (cos^-1(running P.F)- tan (cos^-1(Desired P.F)]

Now KW is 200 KW and running P.F. is 0.8 and desired PF is 1 putting these values into the formula we get:-

KVAR Required= 200 [tan (cos^-1(0.8)- tan (cos^-1(1)]

KVAR Required= 200 [tan 36.86- tan 0]

KVAR Required= 200X 0.75 = 150 KVAR

150 KVAR is additional capacitor bank required for increasing power factor from 0.8 to 1.

This is simpler way of calculating additional KVAR required for power factor improvement.
Visit for Capacitors in Series and Parallel:-

http://electrialstandards.blogspot.in/2015/05/capacitor-in-series-and-parallel.html

Electricity bill understanding/ Electricity bill simplified

Usually understanding electricity is made very simpler by power distribution companies. Whenever new electricity bill received then everyone reads through it to come to know what is the unit consumption this month and whether this consumption is increasing or decreasing everyone uses some trend analysis.

There are some certain terms which should everyone know before understanding electricity bill.

Before going in details please look at the bill mentioned above.

Sanctioned Load

When you look at the bill at the top most there is Name and address is printed on the bill. Then there is Sanctioned load which indicates what is the load sanctioned for Industrial or domestic customers. This is usually sanctioned depending upon load connected at the system .

Maximum Demand Indicator

Then there is MDI means Maximum demand indicator which indicates the Maximum demand for the current month billing period this Maximum demand should not exceed Sanctioned load. For Industrial customers if this maximum demand exceeds the sanctioned load certain amount of penalty will be charged to the customers if that MDI kept on exceeding sanctioned load for three billing cycles then load will be enhanced by power distribution companies depending upon maximum MDI of last three bills and security deposit amount will be charged by power discoms in that new bill. Same will be true for domestic customers but no penalty will be charged for exceeding maximum demand.

Power Factor:-