Wednesday, 23 April 2014

Electrical MS Excel Spreadsheets

Electrical Tools - MS Excel Spreadsheets

Electrical tools (MS Excel Spreadsheets)

This section is dedicated to tools every electrical engineer can use in daily work. These spreadsheets below will make your job much more easier, alowing you to shorten the time used for endless calculations of cables, voltage drop, various selctions of circuit breakers, capacitors, cable size and so on.

Most of spreadsheets are developed by two electrical engineers and programmers mr. Jignesh Parmar and mr. Hemant Kashikar. They all really did an awsome job, you must admit.

Siemens High Voltage Instrument Transformers

Power flow

Current transformers are used for protection, instrumentation, metering and control. It is only the first function that has any bearing on the location of the current transformer.

Ideally the current transformers should be on the power source side of the circuit breaker that is tripped by the protection so that the circuit breaker is included in the protective zone.

In many circuits the power flow can be in either direction and it then becomes necessary to decide which location of fault is most important or likely and to locate the current transformers on the side of the circuit breaker remote from those faults. In the case of generator (and some transformer) circuits it is necessary to decide whether the protection is to protect against for faults in the generator or to protect the generator against system faults.

Current transformers can often be located in the generator phase connections at the neutral end and will then protect the generator from the system faults and to a large degree give protection for faults in the generator.

When current transformers can be accommodated within the circuit breaker, they can in most cases be accommodated on both sides of the circuit breaker and the allocation of the current transformers should give the desired overlapping of protective zones.

Short To Full name

Abbreviation           Expansion
ACDB                                                 Alternate Current Distribution Box
AMF                                                   Auto Mains Failure
AQA                                                   American Quality Assessors
AVM pads                                          Anti Vibration Mould pads
AGL                                                   Above Ground Level
BB                                                      Battery Bank
BIS                                                     Bureau Of Indian Standards
BOM                                                  Bill Of Material
BTS                                                    Base Trans Receiver Station
BV & DV                                           Build Vendor & Delivery Vendors
CELL Site                                          Composition Of Tower, DG and Shelter
CDMA                                               Code Division Multiple Access
CPRI                                                  Centre Of Power Research Institute
CT & PT                                            Current & Potential Transformer
CVCL                                                Certificate Generator Set
DG Set                                               Diesel Generator Set
Day Markings                                     Orange & White pint bands on tower
DPR                                                   Daily Progressive Report
EAT                                                   Electrical Acceptance Testing
EGB                                                   External Grounding Bus Bar
FA                                                      Final Acceptance
FCU                                                   Fan Control Unit
FS                                                      Foll Scope
FTA                                                   First Time Acceptance
GBT                                                   Ground Base Tower
GI                                                      Galvanized Iron
GSM                                                  Globar System Mobilization
ICAO                                                 International Code Of Aviation Organization
IGB                                                    Internal Grounding Bus Bar
ISO                                                    International Organization Of Stanards
ISO-9001 & 14001                            9001 represents Quality & 14001 Environment
ISMB                                                 I Section Medium Beam
MCB                                                  Miniature Circut Board
MHz                                                   Mega Hertz
MIS                                                    Management Information System
MW Antenna                                      Micro Wave Antenna
NGL                                                 Normal Ground Level
Night Beacom                                   Aviation Lamp
OFC                                                   Optical Fibre Cable
O & M                                               Operations & Maintenance
O & E M                                           Operations & Equipment Mainenance
OPC                                                  Ordinary Portland Cement
PABX                                                Public Automatic Branch Exchange
PCB                                                   Printed Circuit Board
PCC                                                   Plain Cement Concrete
PCM                                                  Phase Change Material
PIU                                                    Power Interface Unit
PM                                                    Project Management
PMC                                                 Project Management Consultancy/ Company
PPC                                                  Pozzalana Portland Cement
RC                                                    Rate Contract
RCC                                                 Reinforce Cement Concrete

Selection Of Number Of Cable Cores With Emphasis On Sizing Parameters

Selection Of Number Of Cable Cores With Emphasis On Sizing Parameters (photo by dnvkema.com)

Dependance On Installation Site

The selection of number of cable cores basically depends on the type of system where it is going to be installed.

Generally we have two types of systems:

A perfectly balanced system and
A system with some degree of unbalance (or Unbalanced System).

Generally cable sizing includes below parameters:

Cable installation conditions and the load it will carry
Continuous current rating of the cable
Voltage drop and short circuit considerations
Earth fault loop impedance

Here, I am going to describe that how the number of cores can be selected.

3-Core Cables

These cables are used generally for a perfect balanced 3-phase system. When the currents on the 3-live wires of a 3-phase system are equal and at an exact 120° phase angle, then the system is said to be balanced. The 3-phase loads are identical in all respects with no need of aneutral conductor.

An important example of 3-phase load is electric motor and that is why, they are fed through 3-Core cables in most cases.

3.5-Core Cables

A 3-phase system may have a neutral wire. This wire allows the 3-phase system to be used athigher voltages while it will still support lower voltage single phase loads.

It is not likely in such cases that the loads will be identical, so the neutral will carry the out-of-balance current of the system. The greater the degree of imbalance, the larger the neutral current.

3-5-core cable construction (figure by mitesh-raval.blogspot.com)

When there is some degree of unbalance and the amount of fault current is very small, then 3.5 core cables are used. In these types of cables, a neutral of reduced cross section as compared to the 3-main conductors is used, which is used to carry the small amount of unbalanced currents.

4-Core Cables

When there is severe out-of-balance conditions, the amount of fault current will raise to a very high level. Generally in the case of linear loads, the neutral only carries the current due to imbalance between the phases.

4-core PVC insulated and sheathed copper conductor power cable

The non-linear loads such as switch-mode power supplies, computers, office equipment, lamp ballasts and transformers on low loads produce third order harmonic currents (Definition of Harmonics and Their Origin) which are in the phase of all the supply phases.

These currents do not cancel at the star point of a three-phase system as do normal frequency currents, but add up, so that the neutral carries very heavy third harmonic currents.

That is why the neutral of the cable feeding the equipment are not reduced and made with cross sectional area same as that of the main conductor to carry this high amount of current.

5 and 6-Core Cables

Some conditions may arrive when the amount of fault (neutral) current becomes very large than the phase currents. When the load concerned to this type of situation is fed through a multi-core cable, it is necessary to use a 5-Core or 6-Core Cable.

5-core PVC insulated and sheathed copper conductor power cable

In this condition, two (or three) conductors can be used in parallel formation to carry the high amount of generated unbalanced currents.

Monday, 14 April 2014

Power Substation Guides

Electricity generation

An electrical substation is a subsidiary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers. Electric power may flow through several substations between generating plant and consumer, and may be changed in voltage in several steps.

A substation that has a step-up transformer increases the voltage while decreasing the current, while a step-down transformer decreases the voltage while increasing the current for domestic and commercial distribution. The word substation comes from the days before the distribution system became a grid.

Bend it, charge it, dunk it: Graphene, the material of tomorrow

Graphene is the strongest, thinnest material known to exist. A form of carbon, it can conduct electricity and heat better than anything else.

I just want to say one word to you. Just one word.

No, fans of "The Graduate," the word isn't "plastics."

It's "graphene."

Graphene is the strongest, thinnest material known to exist. A form of carbon, it can conduct electricity and heat better than anything else. And get ready for this: It is not only the hardest material in the world, but also one of the most pliable.Only a single atom thick, it has been called the wonder material.
Graphene could change the electronics industry, ushering in flexible devices, supercharged quantum computers, electronic clothing and computers that can interface with the cells in your body.

Overcoming barriers to renewable energy deployment

Overcoming barriers to renewable energy deployment (photo credit: nickmastrini via Flickr)

Undeservedly second…

Despite some gains in recent years, renewable energy sources make only a modest contribution to the provision of modern energy services worldwide. Why is it so?

The principal constraints to their growth are their costs and their unrewarded environmental characteristics (the continuing and exclusive use of production costs to compare energy options without adjustment for environmental externalities). Some renewables have also been hampered by siting concerns and intermittent supply.

Moreover, there is a variety of challenges stemming from the inertia in turnover of existing energy infrastructure, the relatively recent development of marketable products based on renewable energy, as well as the costs and difficulties of creating new technical, business and human support structures on a global scale.

Research papers

No.	Reasearch / Project	Download
1	The Four Layers of Smart Grid Security
2	Planning application of equipments in hydro power projects
3	Leakage and ground currents: Measurement techniques
4	The applicability of lighting elimination, devices to substations and power lines
5	Active current, Reactive current, Kirchhoff’s laws and Tellegen’s theorem Shared by Mr. Shailesh Kumar
6	Micro Hydro Project: an option for development of Rural Areas Shared by Mr. Pravesh Kafle

How to calculate voltage regulation of distribution line

Introduction to voltage regulation

Voltage (load) regulation is to maintain a fixed voltage under different load.Voltage regulation is limiting factor to decide the size of either conductor or type of insulation.

In circuit current need to be lower than this in order to keep the voltage drop within permissible values. The high voltage circuit should be carried as far as possible so that the secondary circuit have small voltage drop.

Voltage Regulation for 11KV, 22KV, 33KV Overhead Line

Do you know that changing your v-belt can reduce your electrical bill?

With today’s increasing energy costs everyone is looking for a way to have energy efficient systems, but do you know that you can also help reducing this costs by changing your V-Belt drive to synchronous drive?

Today’s industries spend about 70% of the energy running electrical motor systems, so the obvious thing to do will be change them to new energy-efficient units, right?. Well, the answer is: not always; as this will be a high costs and long down time on production.

A high efficiency unit or system is one that has the ability of transmitting the most power with less energy loss. What we see in the industry is that the most common form of energy loss is heat, which is generated by friction.

Economical Voltage for Power Transmission:

Economic generation voltage is generally limited to following values (CBIP Manual).

Economic generation voltage (CBIP Manual)
Total Load	Economical Voltage
Up to 750 KVA	415 V
750 KVA to 2500 KVA	3.3 KV
2500 KVA to 5000 KVA	6.6 KV
Above 5000 KVA	11 KV or Higher

Generally terminal voltage of large generators is 11 kV in India. Step up voltage depends upon Length of transmission line for interconnection with the power system and Power to be transmitted.
High voltage increases cost of insulation and support structures for increased clearance for air insulation but decreases size and hence Cost of conductors and line losses.
Many empirical relations have been evolved to approximately determine economic voltages for power evacuation. An important component in transmission lines is labor costs which are country specific.

Abstract of IE Rules for DP Structure

IER-61-2.	Only one connection with earth has been provided for the frame of A B switch. One more Separate and Distinct connection with earth should be provided for frame of the A B switch.
IER-61-2.	Only one connection with earth has been providing for the frame of the H G fuse. One more Separate and distinct connection with earth should be provided for the frame of HG fuse.
IER -29&5b	The metal cover of the transformer (top cover) on which the HV and or LV busing are Housed should be Looped to earth to avoid any fault current passing through fastening bolts
IE R-9 2.	The earthling lead of the HV lighting arrester is not kept separate but it mixed with other Connections. The earthling lead from the HV lighting arrester should not be used for earthling Any other gear and should be taken to a separate electrodes
IER-51-1 b & 61 -3	The GI pipe enclosing the MV circuits on the secondary side of the transformer are Not earthed. This should be earthed.
IER- 29&9 2	The earth lead from the HV lighting arrestor is taken through GI pipe. The above earth lead Should not Pass through any iron steel pipes.
IER 29&51b	The AB switch handle has not been earthed. The same should be earthed effectively.

Carbon-Core Overhead Transmission Conductor Unveiled

Utilities looking for greater flexibility, reliability and single-failure tolerance for critical transmission lines now have an affordable carbon-fiber option in the new Southwire C7TM Overhead Conductor. The multi-stranded composite core using advanced polymers, resins and thermoplastics from Celanese delivers increased performance and a service life in excess of 40 years.

Southwire has been developing the C7 Overhead Conductor for the past seven years, creating a transmission conductor with nearly double the capacity and less sag than the same diameter ACSR. . The new overhead conductor has a stranded continuous carbon-fiber thermoplastic composite core for rugged flexibility and reliability. The carbon fibers are embedded in a heat-resistant Fortron® PPS polymer matrix and capped with a layer of high-performance PEEK. The design allows for minimum sag at higher power transfer, and the stranded core means there is no single point of failure for the overhead conductor.

The difference between distribution and power transformers

An overview of liquid filled, dry type and GSU transformers

On the distribution level (transmitted power up to 10MVA) there are two main categories of distribution transformers: liquid filled (using mineral oil or replacement fluids such as synthetic or natural esters) and dry type. The liquid filled transformers are the most compact and cost efficient solution, whereas dry type transformers are preferred in environments where fire safety is of special importance such as, for example, underground substations, mining sites, marine and some industrial applications.

Standard versions of distribution transformers are cooled passively as the heat generated by losses is transported away from the core by natural convection of the insulation medium. In the case of liquid filled products, this heat is then transported through the tank walls by thermal conduction and removed by the natural or forced convection of air. Dry transformers in closed environments usually have a forced internal convection flow of air to ensure sufficient cooling of the transformer core.

By Alan McHale

One of the main tasks in delivering a smart grid will be to install and bring together smart grid systems such as AMI and automated demand response with distributed energy and smart buildings to win negawatts. This will go a long way to achieving the main aim of smart grid, which has to be to accommodate the maximum amount of renewable energy on the grid and to reduce carbon emissions.

The smart grid manufacturer, installer, and supply business underwent a massive consolidation in 2012. Investment through venture capital amounted to $779 million after adjusting for senior debt finance transactions.

The structure is changing in a perceptible but slow way with a shift from the dominance of the international major players to the medium and small specialist companies that are increasing their market share. A significant number of new entrants from outside the industry (the information technology and communications businesses) are increasing competition and strengthening the business.

However, the industry is still too fragmented with hundreds of companies. Consolidation will continue for years to come. It is the demand side and structure of the utility market that needs to change if smart grid is to be realized in the next 20 years.

Electrical Power Sector