Tuesday, 20 September 2016

Know about Harmonics and its Effects

Harmonics are the deviation or the distortion of the waveform of its Sinusoidal waveform due to the addition of waveforms of different frequencies.
As per Ohms Law V=I/R,Voltage is proportional to the Current means Current also have a sine waveform except current(which has power factor) does not align perfectly to voltage waveform.
                                         current waveform,voltage waveform,sinewave

The Power supply operates at a standard of 50Hz that means 50Cycles per sec,the voltage changes from positive and negative polarity and back again 50 times per sec.The below is the sinewave of the supply in that the voltage(240V) changes between +240 to -240V thus called alternating voltage.

Figure 2 shows the superimposition of the 3rd order harmonic to the base sine wave due to that the resultant waveform is Distorted waveform(Base+3rd Harmonic).The entire waveform does not follow the Sinusoidal pattern causes unbalance in the load.


                                     sine waveform,supply waveform

Waveform with superimposed harmonics,3rd harmonics,2nd harmonics
The below Fig shows the distorted waveform which is the resultant of the addition of the 3rd harmonic with the fundamental pure sinewave.
Fundamental to Distorted harmonics waveform


The below fig shows the Sine Wave from the Source without harmonics and the fig shows only one cycle having Vmax is the Peak value,Frequency f in Hz and Time period T.

                                    Sinewave of the power supply


The Equation of a Sinewave is written as:

                                     V=VmaxSine(wt)

Note: The harmonics depend on Phase angle,Frequency and also the amplitude.
If the fundamental frequency is given as; E = Vmax(2πƒt),then the complex waveforms will be,

                         

Complex WaveForms due to Harmonics

                       Complex waveform due to the addition of harmonics                   
Harmonic Sequencing

From the below table, Fundamental frequency is either 50Hz or 60Hz. And the 2nd order harmonic frequency will be 100Hz or 120Hz ,the 3rd order harmonic frequency is 150Hz or 180Hz and so on...,

The harmonics are voltages or currents that operate at a frequency that is an integer multiple of the Fundamental Frequency.

Name
Fund.
2nd
3rd
4th
5th
6th
7th
8th
9th
Frequency, Hz
50Hz/60Hz
100/120
150/180
200/240
250/300
300/360
350/420
400/480
450/540
Sequence
+
0
+
0
+
0

Note that in some countries the fundamental frequency will be either 50Hz(UK) or 60Hz(US).

Sequence
Rotation
Harmonic Effect
+
Forward
Excessive Heating Effect
Reverse
Motor Torque Problems
0
None
Adds Voltages and/or Currents in Neutral Wire causing Heating

Common Problems Caused by Harmonics

Overloading Neutral Conductors
The 3-phase system consists of three phase conductors and a neutral conductor. These three phase conductors carry the same amount of current and they used to cancel each other in the neutral conductor makes the load balanced But due to the usage of motors,fans,rectifiers,SMPS causes neutral with increased or twice the current flow of phase current.Hence with balanced load with the currents cancel each other in the neutral conductor, the size of the conductor is minimum, but due to the nonlinear loads, the current draw is higher hence the size of the neutral conductor is bigger than the counterpart.

Overheating Transformers & Losses
The Transformers feeding power to the unbalanced loads like rectifiers,motors, the eddy current loss in the windings is proportional to the square of harmonic current and its frequency thus the losses associated with the transformer with the non-linear load will be twice of the linear load.This condition leads to the overheating of the Transformer which degrades the insulation causes complete failure.

Nuisance Tripping of Circuit Breakers

The RCCB used to check the current between phase to neutral if the neutral current is not same with the phase current then RCCB disconnects power to the Load and also RCCB does not sum the higher frequency components thus sometimes it used to trip.




Thursday, 4 August 2016

RCCB Vs ELCB

                                   RCCB

                                                                           

          


RCCB refers to Residual Current Circuit Breaker which is a rival to the ELCB(Earth Leakage Circuit Breaker). As both the circuit breaker works for the same cause but the difference is RCCB connectivity is different also it gives better protection over ELCB.

ELCB is a voltage operated device which has Line,Neutral, and Earth Connections detects potential in the earth when the voltage is non-zero and indicates that there should be a leakage current in the earth and it protects by tripping.The ELCB can protect from earth fault only  and doesn't provide protection from overload and short circuit so better opt for RCCB than ELCB.

Meanwhile, RCCB which has Line and Neutral connections and the working is when there is a difference in current level from Line to neutral indicates a fault or earth leakage and it trips.As line current always equal to the neutral current which flows back in neutral conductor any difference in current means that somewhere earth fault occurs so the RCCB will get tripped.

The RCCB doesn't require earth connection so that even it can provide shock or fault protection to the device which does not have the earth of its own.

The Tripping of the RCCB is within 30milliSeconds of the earth fault.
The widely used RCCB rating is 30mA and 100mA.
The Human body can withstand up to 30mA.

Like ELCBs,RCCB doesn't protect from the following,

1.Overload(Due to huge current even undetected).
2.Nuisance Tripping(Due to sudden changes in electrical load like switching Airconditioner or Motor etc...)
3.Non-Standard Waveforms(Not guaranteed for the operation by other than nominal waveforms like from halfwave rectifiers).
4.Short Circuits(Due to Line-Neutral Schock).

Friday, 10 June 2016

Best institute for Solar Training In India



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MSME- MINISTRY OF MICRO,SMALL AND MEDIUM ENTERPRISES

                             MSME is a branch of Indian Government,Which is the body for the formulation and administration of rules,regulations and laws for micro,medium and small enterprises.This is providing Employment and training for the peoples to create a skilled workforce in emerging India. The MSME approved institutes are there in every state and the details can be accessed from mnre website.

Location: New Delhi
Facebook: https://www.facebook.com/minmsme/

GERMI – GUJARAT ENERGY RESEARCH & MANAGEMENT INSTITUTE

                        Gujarat Energy Research & Management Institute (GERMI) promoted by Gujarat State Petroleum Corporation Ltd. (A Govt. of Gujarat Undertaking). GSPC is a fully integrated energy company having a presence in various operations like Exploration & Production, Transportation of Gas, and Power Generation, IT services. It is one of the fastest growing state owned companies and has excellent support from Gujarat Govt. as well as from Central Govt.

It has already established a specialised technology & management institute focusing on the Oil & Gas Sector and is actively pursuing initiatives in the areas of research and alternative energy resources.

Location: Gujarat, India
Phone: +91 079-66701362
E-mail: information@germi.org


NPTI – NATIONAL POWER TRAINING INSTITUTE
            
The Primary objective of NPTI includes the below mentioned functions;

1.Operation and Maintenance of Power Stations.
2.All other aspects of Electrical Energy Systems including Transmission,Sub-Transmission and distribution
3.To act as an apex body for initiating and coordinating training programs in the Power Sector of the country
4.To establish and run Training Institutes for Engineers, Operators, Technicians and other personnel of the Power Sector.

Location: Faridabad, India
Phone: 9818897666
E-mail: rkmishra@npti.in


NCPRE – NATIONAL CENTRE FOR PHOTOVOLTAIC RESEARCH AND EDUCATIO             
The National Centre for Photo-voltaic Research and Education (NCPRE) at IIT Bombay was launched in 2010.For the Jawaharlal Nehru National Solar Mission (JNNSM) to succeed, the availability of trained manpower is a prerequisite. NCPRE aims to provide the framework to meet this need.

1.Design and run appropriate post-graduate programmes in PV at IIT Bombay.
2.Design and offer appropriate undergraduate programmes and courses in Energy at IIT Bombay
3.Create appropriate course modules, including laboratory modules, which can be replicated at other institutions and universities.
4.Train teachers at other institutions and universities.
5.Offer IITB's courses through distance education channels.
6.Design and run special programmes (including certificate-level and diploma programmes) for industry personnel on a part-time basis.
7.Run short-term continuing education programmes for industry personnel
8.Train master trainers for teaching technicians.
9.Provide access to a running fabrication and characterisation facilities for researchers and industry users.

Location: Mumbai, India
Phone: +91 22- 2576 4476 ; 4480 ;4479
E-mail: ncpre@iitb.ac.in


GUJARAT INSTITUTE OF SOLAR ENERGY (GISE)

The Gujarat Energy Development Agency's an ISO 9001:2008 certified educational institute that provides technical training Programs on Solar energy.The major objective of the institute is to produce solar energy skilled manpower. 

GISE has set the pace of Renewable Energy Development in the country with the foundation laid for Asia’s first Solar Park that envisaged an investment of Rs. 7500 crore. The Solar Park will be established on 2,000 ha of arid land in Village: Charanka (Taluka: Santalpur Taluka) District Patan bordering Pakistan. Plots have been allocated to 16 Private investors to generate to 176 MW solar power.

Courses Offered
Course NameDurationEligibility
Diploma in Solar System & Inverter Installation & Servicing1 Year (Short Term)12th Passed (Any Stream) / ITI
Diploma in Solar System & Environmental Engineering6 Semester12th Passed (Any Stream) / ITI
B.Tech in Solar & Environmental Engineering8 Semester10+2(Science + Maths)
B.Tech in Solar & Environmental Engineering
(Lateral Entry to 3rd Semester)
6 SemesterPolytechnic Diploma of 3 year after 10th Class
M.tech in Solar & Environmental Engineering4 SemesterPassed in B.E./B.Tech
Certificate in Solar Photo-voltaic Application , Design & Technology3 MonthsPassed in Diploma, Bachelor or Master in Any Stream
Solar Technical Workshop3 DaysPassed in 12th , Diploma, I.T.I, Bachelor or Master in Any Stream

Location: Gujarat, India
Phone: 079 – 2768 01 22
E-mail: info@gise.in


NISE – NATIONAL INSTITUTE OF SOLAR ENERGY

The National Institute of Solar Energy (formerly Solar Energy Centre) was established by MNRE in 1982. NISE is an autonomous institute under Ministry of New and Renewable Energy, Government of India established to facilitate the Research & Development, Testing, Certification, Skill development activities in the field of Solar energy technologies.

NISE also supports the ministry in the implementation of prestigious National Solar mission. The institute is committed to the development and demonstration of solar energy related technologies and its applications to the common man in the country.

Location: Gurgaon, India (Campus)
Telefax: 0091-124-2579207
E-mail: sec.nic@in


RENEWABLE ENERGY CENTRE MITHRADHAM

Mithradham also offers student internship training in renewable energy. The aim of the training programme is to offer hands on training on the core concepts necessary to work with all PV systems, including system components, site analysis, PV module criteria, mounting solutions, safety and commissioning. We train decision makers, technicians, and end-users in order to create sustainable renewable energy projects

The present programme offers a one week training with German experts who have international exposure and expertise in on-grid and off-grid solar P-V. It is tailored to all who have a basic knowledge in electricity and intend to make use of it. Practical installation and study visits to different solar installations are also offered as a part of the programme. Consultancy services of the expert is available by prior appointment during the training programme.

A certificate will be issued at the end of the training programme. The following are the areas of theoretical and practical training:
  1. Basics of solar energy
  2. Stand alone PV systems: Planning, Designing and Installation
  3. Grid connected systems
  4. Solar cable technology
  5. Maintenance and Surveillance of PV installations
Location: Kerala, India
Phone: +91(0)484 2839185
E-mail: director@mithradham.org


GSES – GLOBAL SUSTAINABLE ENERGY SOLUTIONS

GSES is leading the industry in providing accredited solar training for the safe design and installation of grid connected solar systems. It offers solar training and renewable energy courses to cater to a broad range of students. Their courses include:
  1. Grid Connected PV Systems Design and installation (Online and face-to-face)
  2. Standalone Solar PV Systems Design and Installation (Face-to-face)
  3. Rooftop PV Systems Design and Installation (Face-to-face)
  4. Solar PV Best Practices (Face-to-face)
  5. Solar Power System Fundamentals (Online)
  6. Solar PV course for Startups and Entrepreneurs (Online and face-to-face)
Location: New Delhi, India
Phone: +91 1140587622
E-mail: info@gses.in

PROMOTERS AND RESEARCHERS IN NON-CONVENTIONAL ENERGY – PRINCE

            PRINCE (Promoters and Researchers In Non-Conventional Energy) provide "Entrepreneurship Training in Renewable Energy". This includes hands on/Field training as well as classroom sessions. Many entrepreneurs in solar concentrating cookers, Scheffler concentrators are their trainees.


Location: Maharashtra, India
Phone: 91 2562 271795
E-mail: chandak@princeindia.org

Thursday, 11 February 2016

Lithium ion batteries



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Lithium ion batteries,These batteries are now becoming popular especially in telecom sectors,Space projects etc...because of their charging and discharging feature,Compact,energy density and finally the monitoring feature involved in Li-Ion batteries.

Working of a Battery?

The batteries is a storage device,that converts chemical energy.The batteries are having 3 major parts or components.Anode(negatively charged),Cathode(Positively charged) and Electrolytes.

For example,Take one container and fill it with diluted sulfuric acid as the electrolyte. Now immerse zinc and one copper rod in the solution and connect them externally by an electric load. Now your simple voltaic cell is completed. Current will start flowing through the external load.

Zinc in diluted sulfuric acid gives up electrons as below:

                                                  
These Zn + + ions pass into the electrolyte, and their concentration is very high near the zinc electrode. As a result of the above oxidation reaction, the zinc electrode is left negatively charged and hence acts as cathode. The diluted sulfuric acid and water disassociate into hydronium ions as given below:

                                       
Due to the high concentration of Zn + + ions near the cathode, the H3O+ ions are repelled towards the copper electrode and get discharged by removing electrons from the copper atoms. The following reaction takes place at the anode:

                                       
As a result of the reduction reaction taking place at copper electrode, copper is left positively charged and hence it acts as the anode.


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Lithium ion Battery?

These batteries having better features compared to other lead acid or other batteries because there will be a monitoring section provided which can give you all real time data's at that time, means Voltage of individual cells,battery pack,total voltage,cell temperature,Over current or Under current etc...., each and every parameters of the battery including SOH and SOC also tracked using the in-build BMS(Battery Monitoring System).


The Lithium ion batteries have high energy density, means the amount of energy stored per unit volume is higher than the traditional Lead acid batteries so that the size of the battery was compact too.

The Li-Ion is a lightweight metal so that it is easy to form ions at the time of chemical reaction,The Li-ion battery can store as much as twice of the power Lead Acid battery can hold and also these batteries are also environmentally friendly but susceptible to 100% discharge so 80% discharge is recommended.

Let us take an example of 48V/75AH Li-Ion battery,so it has 15 no of 3.2V cells connected in series,thus makes you 48V battery.thus for the same size it give twice the power of other battery types.

These batteries have some modern electronics involved to better understand each and every parameters,so mainly BMS (Battery monitoring system),Contractors,Temperature sensors,Shunt,RS485,Data Logger,CAN.

The BMS may contain MOSFET to replace contractors which are responsible for charging and discharging,The BMS can able to control the battery from fail due to any Over or Under current/Voltage/Temperature,also it has alarms in case of any problems occurred so that these BMS are very helpful to protect batteries by monitoring all possible parameters.


RS485 which is used to monitor the parameters by connecting PC/Laptop.CAN communication is used to communicate between each battery so that the data logger can store the data of all the batteries.Data logger is used to log all the parameters of the battery and generally the Master module hold data logger and CAN communication allow to get information from each battery.


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The commercially used negative electrode is graphite and  positive electrode will be one of these three materials- lithium cobalt oxide, a polyanion-such as lithium iron phosphate or a spinel -such as lithium manganese oxide.The electrolyte will be a mixture of some organic carbonates such as ethyliene carbonate or diethyl carbonate containing complexes of Li ions,

Charging:

The external voltage was given through any external charger with the same polarity is applied between the electrodes, thus the charging process will start. The lithium atoms leave the metal oxide structure and ionize into Li+ ions under the release of an electron of each one. In this process Li+ ions diffuse to the negative electrode(anode). At the surface of the graphite particles the Li+ ions and electrons recombine with each other forming neutral lithium atoms and are reintercalated into the molecular structure of the graphite particles,otherwise Lithium is deposited in the anode.When no more ions will flow, the battery is fully charged and ready to use.

Ref:TUM EES YouTube Channel

Discharging

During discharge, lithium atoms oxidize by forming Li+ ions and electrons, whereas Li+ ions move to the positive electrode diffusing through the electrolyte and the separator. The electrons flow from the negative electrode to the positive on the external circuitry, where the resulting current flow can be used for an application. At the positive electrode the electrons recombine with the Li+ ions and are stored in the molecular structure of the active material, otherwise Lithium is deposited in the cathode.When all the ions have moved back, the battery is fully discharged and needs charge again.