മഴക്കാലത്തു സ്വീകരിക്കേണ്ട വൈദ്യുത സുരക്ഷാ മുൻകരുതലുകൾ

How take C class Electrical Contractor License

Supervisor B Grade Examination (Part I) 2018 Result

Supervisor B Grade Examination (Part I) 2018 Result

ELECTRICAL CONTRACTOR മാര്‍ക്ക് ചെയ്യാവുന്ന ജോലിയുടെ കണക്ക്

ELECTRICAL CONTRACTOR മാര്‍ക്ക് ചെയ്യാവുന്ന ജോലിയുടെ കണക്ക്



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27-11-2018 ലെ KSELB യോഗത്തിലെ പ്രധാനപ്പെട്ട തീരുമാനങ്ങൾ

  

27-11-2018 ലെ KSELB യോഗത്തിലെ പ്രധാനപ്പെട്ട  തീരുമാനങ്ങൾ 

1. Professional Diploma in Industrial Electrical Engineering (PDIEE), Professional Diploma in Computerised Instrumentation (PDCI),എന്നീ 12 മാസ കാലാവധിയുള്ള കോഴ്സുകളുടെ സിലബസ്സിൽ വയർമാൻ പരീക്ഷയ്ക്കാവശ്യമായ വിഷയങ്ങൾ ഉൾപ്പെട്ടിരിക്കുന്നതിനാലും ഈ രണ്ട്‌ കോഴ്സുകളും 10 മാസ ദൈർഘ്യമുള്ളതും വയർമാൻ പരീക്ഷയ്ക്ക് അനുവദിച്ചിട്ടുള്ളതുമായ "ഇലക്ട്രിക്കൽ വയർമാൻ ആൻറ് സർവീസിങ്" എന്ന കോഴ്സിന് തുല്യമാണ് എന്ന തുല്യത സർട്ടിഫിക്കറ്റ് ഡയറക്ടർ, സെന്റർ ഫോർ കണ്ടിന്യൂയിങ് എഡ്യൂക്കേഷൻ, കേരള നല്കിയിട്ടുള്ളതിനാലും മേൽപ്പറഞ്ഞ രണ്ട്‌ കോഴ്സുകൾ പഠിച്ചു ജയിച്ചവരെ വയർമാൻ പരീക്ഷയ്ക്കു പങ്കെടുക്കാൻ അനുവദിക്കണമെന്ന് യോഗം തീരുമാനിച്ചു.

 

2. സി- ക്ലാസ് കോൺട്രാക്ടർമാർ ജോലി ചെയ്യുന്ന പ്രതിഷ്ഠാപനങ്ങളിൽ എർത്ത് റെസിസ്റ്റൻസ് അളക്കേണ്ടത് അനിവാര്യമായതിനാൽ, നിലവിലുള്ള ഉപകരണങ്ങളായ ഇൻസുലേഷൻ ടെസ്റ്റർ, മൾട്ടിമീറ്റർ ഇവയ്ക്കു പുറമെ   എർത്ത് ടെസ്റ്റർ കൂടി സി- ക്ലാസ്  കോൺട്രാക്ടർമാർക്ക് ഉണ്ടായിരിക്കണം എന്ന് യോഗം തീരുമാനിച്ചു.  

 

3. കരാർ പ്രകാരം ഒരു കോൺട്രാക്ടർ ജോലി ഏറ്റെടുത്ത ശേഷം ജോലി കൃത്യസമയത്തു പൂർത്തീകരിക്കാതെ വരുമ്പോൾ, പ്രതിഷ്ഠാപന ഉടമയ്ക്ക്  നിലവിലെ കോൺട്രാക്ടറെ നിയോഗിക്കുന്നതിനു മുൻ കോൺട്രാക്ടറിൽ നിന്നുമുള്ള എൻ.ഒ.സി ആവശ്യമാണ്.  എന്നാൽ ഇലക്ട്രിക്കൽ ഇൻസ്പെക്ടറേറ്റിൽ നിന്നുമുള്ള 'സ്കീം അപ്പ്രൂവൽ' ലഭിക്കുന്നതിനു മുൻപാണ് കോൺട്രാക്ടറെ മാറ്റുന്നതെങ്കിൽ മുൻ കോൺട്രാക്ടറിൽ നിന്നുമുള്ള എൻ.ഒ.സി വാങ്ങേണ്ടതില്ല എന്ന് യോഗം തീരുമാനിച്ചു.

 

4. 'ബി' ക്ലാസ് ലൈസൻസ് ഉള്ളവർക്ക് (150kW & 250kW only) 3 വർഷത്തെ എക്സ്പീരിയൻസ് (കുറഞ്ഞത് 10 വർക്ക് എങ്കിലും) ഉണ്ടെങ്കിൽ അവർക്ക് കെ.സ്.ഇ.ബി.ലിമിറ്റഡ് / ലൈസെൻസിയുടെ എൽ.റ്റി ലൈൻ വർക്കുകൾ ചെയ്യുന്നതിനുള്ള ലൈസൻസിനായി അപേക്ഷിക്കാവുന്നതും ആയത് നിലവിലുള്ള ലൈസൻസിൽ രേഖപ്പെടുത്തി നല്കാവുന്നതുമാണ് എന്ന് യോഗം തീരുമാനിച്ചു.

 

Full form of Electrical part

Full form of Electrical part

XLPE = Cross Linked Poly Ethelene Cable

PVC = Poly Vinyle Chloride Cable

PILC = Paper Insulated Lead Covered Cable

MCB = Miniture Circuit Breaker

ELCB = Earth Leakage Circuit Breaker

MCCB = Moulded Case Circuit Breaker

BDV = Breake Down Voltage

MOCB = Minimum Oil Circuit Breaker

ACB = Air Circuit Breaker

SF6 = Surfar Hexa Floraid

VCB = Vaccuam Circuit Breaker

OCB = Oil Circuit Breaker

SF6CB = Salfar Hexa Floride Circuit Breaker

HT = High Tension

LT = Low Tension

ST = Super Tension

EHT = Extra High Tension

ESV = Extra Super Voltage

IDMT = Inverse Definit Minimum Timmelag Relay

DT = Definit Time lag relay

RCCB =Residual Current Circuit Breaker

RCD = Residual Circuit Device

RCBO = Residual Circuit Breaker with Overload

HRC = High Reputuring Capacity

LED =Light Emiting Diod

CFL = Compact Fluresent Lamp

Electrical Wireman Exam notification 2019

Electrical Wireman Exam notification 2019   Click Here


wireman Exam malayalam Note     Click Here


Electrical Supervisor Exam Malayalam Note   Click Here

Indian Electricity Rule 2003

supervising malayaam note   Click Here

Wireman malayalam note        Click Here

                                      MINISTRY OF LAW AND JUSTICE

                                             (Legislative Department)

                                 New Delhi, the 2nd June, 2003.Jyaistha 12, 1925 (Saka)

The following Act of Parliament received the assent of the President on the 26th May, 2003, and is hereby published for general information:

                                                 THE ELECTRICITY ACT, 2003

                                                        [No.36 of 2003]

                                                                                                             [26th May, 2003] 

                 An Act to consolidate the laws relating to generation, transmission, distribution, trading and use of electricity and generally for taking measures conducive to development of electricity industry, promoting competition therein, protecting interest of consumers and supply of electricity to all areas, rationalization of electricity tariff, ensuring transparent policies regarding subsidies, promotion of efficient and environmentally benign policies, constitution of Central Electricity Authority, Regulatory Commissions and establishment of Appellate Tribunal and for matters connected therewith or incidental thereto.

Be it enacted by Parliament in the Fifty-fourth Year of the Republic of India as follows:-

                                                                               PART I

                                                                       PRELIMINARY

Section  1. (Short title, extent and commencement) --- (1) This Act may be called the Electricity Act, 2003.

(2) It extends to the whole of India except the State of Jammu and Kashmir.

(3) It shall come into force on such date as the Central Government may, by notification, appoint:

                Provided that different dates may be appointed for different provisions of this Act and any reference in any such provision to the commencement of this Act shall be construed as a reference to the coming into force of that provision.

Section 2. (Definitions): --- In this Act, unless the context otherwise requires,--

(1)“Appellate Tribunal” means the Appellate Tribunal for Electricity established under section 110;

(2) "appointed date" means such date as the Central Government may, by notification, appoint;

(3) "area of supply” means the area within which a distribution licensee is authorised by his licence to supply electricity;

(4) "Appropriate Commission” means the Central Regulatory Commission referred to in sub-section (1) of section 76 or the State Regulatory Commission referred to in section 82 or the Joint Commission referred to in section 83, as the case may be ;

(5) "Appropriate Government" means, -

 (a) the Central Government, -

(i) in respect of a generating company wholly or partly owned by it;

 (ii) in relation to any inter-State generation, transmission, trading or supply of electricity and with respect to any mines, oil-fields, railways, national highways, airports, telegraphs, broadcasting stations and any works of defence, dockyard, nuclear power installations;

(iii) In respect of National Load Despatch Centre; and Regional Load Despatch Centre;

 (iv)  In relation to any works or electric installation belonging to it or under its control;

(b) In any other case, the State Government, having jurisdiction under this Act;

(6) “Authority” means the Central Electricity Authority referred to in sub-section (1) of section 70;

(7) "Board" means, a State Electricity Board, constituted before the commencement of this Act, under sub-section (1) of section 5 of the Electricity (Supply) Act, 1948;

(8) “Captive generating plant” means a power plant set up by any person to generate electricity primarily for his own use and includes a power plant set up by any co-operative society or association of persons for generating electricity primarily for use of members of such cooperative society or association;

 (9) "Central Commission" means the Central Electricity Regulatory Commission referred to in sub-section (1) of section 76;

(10) "Central Transmission Utility" means any Government company which the Central Government may notify under sub-section (1) of section 38;

(11) "Chairperson" means the Chairperson of the Authority or Appropriate Commission or the Appellate Tribunal, as the case may be;

(12) “Cogeneration” means a process which simultaneously produces two or more forms of useful energy (including electricity);

(13) "company" means a company formed and registered under the Companies Act, 1956 and includes any body corporate under a Central, State or Provincial Act;

(14) "conservation" means any reduction in consumption of electricity as a result of increase in the efficiency in supply and use of electricity;

(15) "consumer" means any person who is supplied with electricity for his own use by a licensee or the Government or by any other person engaged in the business of supplying electricity to the public under this Act or any other law for the time being in force and includes any person whose premises are for the time being connected for the purpose of receiving electricity with the works of a licensee, the Government or such other person, as the case may be;

(16) “dedicated transmission lines" means any electric supply-line for point to point transmission which are required for the purpose of connecting electric lines or electric plants of a captive generating plant referred to in section 9 or generating station referred to in section 10 to any transmission lines or sub-stations or generating stations, or the load centre, as the case may be;

(17) "distribution licensee" means a licensee authorised to operate and maintain a distribution system for supplying electricity to the consumers in his area of supply;

(18) "distributing main" means the portion of any main with which a service line is, or is intended to be, immediately connected;

(19) "distribution system" means the system of wires and associated facilities between the delivery points on the transmission lines or the generating station connection and the point of connection to the installation of the consumers;

(20) "electric line" means any line which is used for carrying electricity for any purpose and includes

(a) any support for any such line, that is to say, any structure, tower, pole or other thing in, on, by or from which any such line is, or may be, supported, carried or suspended; and

(b) any apparatus connected to any such line for the purpose of carrying electricity;

(21) "Electrical Inspector" means a person appointed as such by the Appropriate Government under sub-section (1) of section 162 and also includes Chief Electrical Inspector;

(22) "electrical plant" means any plant, equipment, apparatus or appliance or any part thereof used for, or connected with, the generation, transmission, distribution or supply of electricity but does not include-

(a) an electric line; or

(b) a meter used for ascertaining the quantity of electricity supplied to any premises; or

 (c) an electrical equipment, apparatus or appliance under the control of a consumer;

(23) "electricity" means electrical energy-

(a) generated, transmitted, supplied or traded for any purpose; or

(b) used for any purpose except the transmission of a message;

(24) "Electricity Supply Code" means the Electricity Supply Code specified under section 50;

(25) "electricity system” means a system under the control of a generating company or licensee, as the case may be, having one or more –

(a) generating stations; or

 (b) transmission lines; or

(c) electric lines and sub-stations; and when used in the context of a State or the Union, the entire electricity system within the territories thereof;

(26) "electricity trader" means a person who has been granted a licence to undertake trading in electricity under section 12;

(27) “franchisee means a persons authorised by a distribution licensee to distribute electricity on its behalf in a particular area within his area of supply; (28) "generating company" means any company or body corporate or association or body of individuals, whether incorporated or not, or artificial juridical person, which owns or operates or maintains a generating station;

(29) "generate" means to produce electricity from a generating station for the purpose of giving supply to any premises or enabling a supply to be so given;

(30) "generating station" or “station” means any station for generating electricity, including any building and plant with step-up transformer, switchgear, switch yard, cables or other appurtenant equipment, if any, used for that purpose and the site thereof; a site intended to be used for a generating station, and any building used for housing the operating staff of a generating station, and where electricity is generated by water-power, includes penstocks, head and tail works, main and regulating reservoirs, dams and other hydraulic works, but does not in any case include any sub-station;

(31) “Government company” shall have the meaning assigned to it in section 617 of the Companies Act, 1956;

 (32) "grid" means the high voltage backbone system of inter-connected transmission lines, sub-stations and generating plants;

(33) "Grid Code" means the Grid Code specified by the Central Commission under clause (h) of sub-section (l) of section 79;

(34) "Grid Standards" means the Grid Standards specified under clause (d) of section 73 by the Authority;

(35) "high voltage line” means an electric line or cable of a nominal voltage as may be specified by the Authority from time to time; (36) “ inter-State transmission system” includes –

(i) any system for the conveyance of electricity by means of main transmission line from the territory of one State to another State;

(ii) the conveyance of electricity across the territory of an intervening State as well as conveyance within the State which is incidental to such inter-State transmission of electricity;

 (iii) the transmission of electricity within the territory of a State on a system built, owned, operated, maintained or controlled by a Central Transmission Utility. (37) “intra-State transmission system” means any system for transmission of electricity other than an inter-State transmission system ; (38) “ licence” means a licence granted under section 14;

(39) “ licensee” means a person who has been granted a licence under section 14;

 (40) “ line” means any wire, cable, tube, pipe, insulator, conductor or other similar thing (including its casing or coating) which is designed or adapted for use in carrying electricity and includes any line which surrounds or supports, or is surrounded or supported by or is installed in close proximity to, or is supported, carried or suspended in association with, any such line;

 (41) “local authority” means any Nagar Panchayat, Municipal Council, municipal corporation, Panchayat constituted at the village, intermediate and district levels, body of port commissioners or other authority legally entitled to, or entrusted by the Union or any State Government with, the control or management of any area or local fund;

42) "main” means any electric supply- line through which electricity is, or is intended to be, supplied ;

 (43) "Member" means the Member of the Appropriate Commission or Authority or Joint Commission, or the Appellate Tribunal, as the case may be, and includes the Chairperson of such Commission or Authority or Appellate Tribunal;

 (44) "National Electricity Plan" means the National Electricity Plan notified under sub-section (4) of section 3;

 (45) “National Load Despatch Centre” means the Centre established under subsection (1) of section 26;

 (46) “notification” means notification published in the Official Gazette and the expression “notify” shall be construed accordingly;

(47) “open access” means the non-discriminatory provision for the use of transmission lines or distribution system or associated facilities with such lines or system by any licensee or consumer or a person engaged in generation in accordance with the regulations specified by the Appropriate Commission;

 (48) “overhead line” means an electric line which is placed above the ground and in the open air but does not include live rails of a traction system;

 (49) “person” shall include any company or body corporate or association or body of individuals, whether incorporated or not, or artificial juridical person; (50) "power system" means all aspects of generation, transmission, distribution and supply of electricity and includes one or more of the following, namely:-

(a) generating stations;

(b) transmission or main transmission lines;

(c) sub-stations;

(d) tie-lines;

(e) load despatch activities;

(f) mains or distribution mains;

(g) electric supply-lines;

 (h) overhead lines;

(i) service lines;

(j) works;

(51) “premises” includes any land, building or structure;

(52) “prescribed” means prescribed by rules made by the Appropriate Government under this Act;

 (53) "public lamp" means an electric lamp used for the lighting of any street;

(54) "real time operation" means action to be taken at a given time at which information about the electricity system is made available to the concerned Load Despatch Centre;

(55) “Regional Power Committee” means a committee established by resolution by the Central Government for a specified region for facilitating the integrated operation of the power systems in that region;

(56) "Regional Load Despatch Centre" means the Centre established under subsection (1) of section 27;

 (57) "regulations" means regulations made under this Act;

(58) “repealed laws” means the Indian Electricity Act, 1910, the Electricity (Supply) Act, 1948 and the Electricity Regulatory Commissions Act, 1998 repealed by section 185;

(59) "rules " means rules made under this Act;

(60) “schedule” means the Schedule to this Act;

(61) "service-line" means any electric supply-line through which electricity is, or is intended to be, supplied –

 (a) to a single consumer either from a distributing main or immediately from the Distribution Licensee's premises; or

(b) from a distributing main to a group of consumers on the same premises or on contiguous premises supplied from the same point of the distributing main;

(62) "specified" means specified by regulations made by the Appropriate Commission or the Authority, as the case may be, under this Act;

(63) “stand alone system” means the electricity system set-up to generate power and distribute electricity in a specified area without connection to the grid;

(64) "State Commission" means the State Electricity Regulatory Commission constituted under sub-section (1) of section 82 and includes a Joint Commission constituted under sub-section (1) of section 83;

(65) "State Grid Code" means the State Grid Code specified under clause (h) of sub-section (1) of section 86;

(66) "State Load Despatch Centre" means the centre established under subsection (1) of section 31;

(67) "State Transmission Utility" means the Board or the Government company specified as such by the State Government under sub-section (1) of section 39;

 (68) "street" includes any way, road, lane, square, court, alley, passage or open space, whether a thoroughfare or not, over which the public have a right of way, and also the roadway and footway over any public bridge or causeway;

(69) "sub-station" means a station for transforming or converting electricity for the transmission or distribution thereof and includes transformers converters, switch-gears, capacitors, synchronous condensers, structures, cable and other appurtenant equipment and any buildings used for that purpose and the site thereof;

(70) "supply", in relation to electricity, means the sale of electricity to a licensee or consumer;

 (71) "trading" means purchase of electricity for resale thereof and the expression "trade" shall be construed accordingly;

(72) “transmission lines" means all high pressure cables and overhead lines (not being an essential part of the distribution system of a licensee) transmitting electricity from a generating station to another generating station or a substation, together with any step-up and step-down transformers, switch-gear and other works necessary to and used for the control of such cables or overhead lines, and such buildings or part thereof as may be required to accommodate such transformers, switch-gear and other works;

(73) "transmission licensee” means a licensee authorised to establish or operate transmission lines;

(74) "transmit" means conveyance of electricity by means of transmission lines and the expression "transmission" shall be construed accordingly;

(75) "utility" means the electric lines or electrical plant, and includes all lands, buildings, works and materials attached thereto belonging to any person acting as a generating company or licensee under the provisions of this Act;

(76) "wheeling" means the operation whereby the distribution system and associated facilities of a transmission licensee or distribution licensee, as the case may be, are used by another person for the conveyance of electricity on payment of charges to be determined under section 62;

 (77) "works" includes electric line, and any building, plant, machinery, apparatus and any other thing of whatever description required to transmit, distribute or supply electricity to the public and to carry into effect the objects of a licence or sanction granted under this Act or any other law for the time being in force.

Electrician Courses and Classes Overview

Electrician Courses and Classes Overview

Electrician courses often focus on electrical skills in maintenance, construction or industrial applications, and they're typically available through diploma, certificate and associate's degree programs. Read on for more info about common electrician courses.

Electrical safety

Principles of DC/AC electricity

National Electrical Code

Cabling and wiring

Electrical system design

Trigonometry and algebra

List of Classes

Electrical Safety and Tools Course

This course covers general and accepted safety rules and practices for working with electrical circuits. Students gain a thorough understanding of federal, state and local safety rules and regulations. The selection and use of hand and power tools for electrical wiring as well as the instruments used for electrical measuring are addressed.

Commercial Wiring Course

Students learn commercial and industrial wiring through the examination of building plans. They also examine the wiring of appliances and equipment in a commercial structure. Areas of study include safety procedures, grounding techniques, over-current protection and raceway panel board installation. The course may include a lab section wherein students can practice wiring.

Blueprint Reading Course

This course teaches students to read electrical blueprints. The class uses the National Electrical Code manual, the national safety standard for electrical wiring used by national, local and state law. Curriculum covers circuit analysis, branch circuit calculations, electrical theory and load calculations. A lab component affords students the opportunity for hands-on experience wiring a building according to blueprints.

Photovoltaic (PV) Theory and Systems Design Course

As solar energy becomes a more viable alternative to the electrical energy supplied by power plants, there is an increasing need for people who know how to install PV systems. This course provides an introduction to the various types of photovoltaic cells and how they are put together to form modules. Students learn how to use the National Electrical Code to design and install PV systems correctly. This combination lecture and lab course prepares those interested in solar energy installation to take the North American Board of Certified Energy Practitioners (NABCEP) Entry Level Certificate of Knowledge test.

Fault Current Calculation

Question

A 400 KVA ,11 KV/415 volt transformer is to be installed at the premises of 
a proposed industries. The fault level at the 11 KV sides of the consumers 
Premises is 250 MVA the earth resistivity at the site was measured and 
Found to be 150 ohm meter find the number of earth electrode required 
And size of earthing  conductor on  HT and LT side .assume Duration of earth 
Fault as 3 second.
The percentage of impedance of the transformer is 5%

MALAYALAM NOTE CLICK HERE

Answer

1. Transformer Capacity = 400 KVA
2. fault level at 11 KV = 250 MVA
3. Soil Resistivity = 150 ohm meter
4. Duration of Earth Fault = 3 second
5. percentage impedance of the transformer = 5 %
6. Assume base MVA = 100 
7. earth plate size = 1.2 × 1.2 × 0.12 mtr (Standerd)
8. Area of plate Both side =2.88 m2
9. Current Density assumed as = 118 A / Sq mm for Copper
Formula applicable = 
Power = √(3 )×V I
I =P/(√3×V)
For rectifying current density =〖7.57 ×10 〗^3/√(ϱ×t)   (Standerd value)
Calculation 
Fault level at 11 KV =250 MVA
There for percentage impedance at 11 KV side assuming 100 MVA as Base=
= (Base MVA)/(11 KV side fault level)
= (100 )/250 × 100 = 40 %
Transformer 400 KVA Impedance = 5 %
There for
Impedance of the transformer at 100 MVA Base = 
= (transformer percentage impedence )/(transformer capacity in MVA)  × 100=
 (5 )/(.400) × 100 = 1250 %
There for
Total impedance of LT side of the transformer = 40 + 1250 = 1290 %
LT side
Fault level at LT side = (Base MVA×100)/(Total Impedence) × 100 
Fault level at LT side = 100/1290 × 100 = 7.75 MVA
Fault current LT side  = (Fault level in Volt Ampiar)/(√3×415 volt)
Fault current LT side  = (7.75 ×〖10〗^6)/(√3×415 volt) = 10781.84 A
Current density Assumed as = 118 A / Sq mm For Copper and there for Size of 
the  earth Conductor Required =
=(Fault  current )/(Current density of the Copper) = 10781.84/118 = 91.37 mm2
Standerd size of the copper 25× 6 copper strip of 150 Sq mm
There for we can use 25 × 6 mm copper strip for earthing
HT Side
Fault current at 11 KV side =(Fault current at 11 KV side )/(√3×11) 
Fault current at 11 KV side =(250 ×1000)/(√3×11) = 131121.59 A (13122 A)
Permissible current density = 〖7.57 ×10 〗^3/√(ϱ×t)  
Permissible current density = 〖7.57 ×10 〗^3/√(150×3 )  = 356.8 Ambiar/m2
Total area of plate electrode required for the fault level current =
= (Fault  level current  )/(current density)  = (13122  )/356.8  = 36.77 m2
Hence number of plate earth required (Plate) =
=  (Total area of plate electrode required for the fault level current  )/(Area of the plate Both side)  
=  (36.77 )/2.88  =12.77
Number of Earth Plate= 12.77 = 13 plat

MALAYALAM NOTE CLICK HERE

Efficiency of Transformer

Efficiency of Transformer

Transformer efficiency may be defined as the ratio between Output and Input.

Transformer Efficiency = Output / Input

On specified power factor and load, the transformer efficiency can be found by dividing its output on Input (similar to other electrical machines i.e. motors, generators etc). But the values of both Input and Output should be same in unites (i.e. in Watts, kilowatts, megawatts etc)

But note that a transformer has very high efficiency because the losses occur in transformer are very low. Since the Input and Output almost equal, therefore measurement of input and output is practically not possible. The best way to find the transformer efficiency is that, first determine the losses in transformer and then calculate the transformer efficiency with the help of those losses calculation.

Formulas for Transformer Efficiency

Efficiency = η = Output / Input

Efficiency = η= Output / (Output + Losses) ….. (As Input = Output +Losses)

Efficiency = η= Output / (Output +Copper Losses + Iron Losses)

You may also find the Efficiency by the following formula

Efficiency = η= Output / Input Efficiency = η = (Input – Losses) / Input ….. 

(As Output = Input – Losses)

Taking LCM

As we know that the rating of Transform is expressed in kVA not in kW. But the efficiency doesn’t depend on VA i.e. it would be expressed in Power Watts (kW) not in kVA. Although, the Losses are directly proportional to VA (Volt-Amperes), thus, efficiency depends on Power factor on every kind of VA load. And the efficiency would be maximum on unity (1) Power factor.

Condition for Maximum Efficiency of Transformer

We know that,

Copper Loss = WC = I12 x R1   or    I22 x R2

Iron Loss= WI = Hysteresis Loss + Eddy Current Loss = WI = WH + WE

Suppose to the primary side of transformer…

Primary Input = P1 = V1 x I1 Cosθ1

Efficiency = η = Output / Input

Efficiency = η = (Input – Losses) / input ….. (As Output = Input – Losses)

Efficiency = η = (Input – Copper losses – Iron Losses)/Input

Efficiency = η = (P1 – WC – WI) / P1

Efficiency = η = (V1 x I1 Cosθ1 – I12  x R1 – WI) / V1 x I1 Cosθ1

Taking LCM

Efficiency = η = 1- (I12 x R1 / V1I1 Cosθ1) – (WI / V1 x I1 Cosθ1)

Or

Efficiency = η = 1- (I1 x R1 / V1 Cosθ1) – (WI / V1 x I1 Cosθ1)

Differentiate both sides with respect to I1

Dη / dI1 = 0 – ( R1 / V1 Cosθ1) + (WI /V1 x I12 Cosθ1)

Dη / dI1= – ( R1 / V1 Cosθ1) + (WI / V1 x I12 Cosθ1)

For Maximum Efficiency, the value of (Dη / dI1) should be Minimum i.e.

Dη / dI1 = 0

The above Equation can be written as

R1 / (V1 Cosθ1) = (WI /V1 x I12 Cosθ1)

Or

WI = I12 x R1     or       I22 x R2

Iron Loss = Copper Loss

The value of Output current (I2) on which Maximum efficiency can be gained

I2 = √ (WI / R2)

The value of output current (I2) is the actor who equals the value of copper loss and iron loss (i.e. Copper Loss = Iron Loss)

Doing so, the maximum efficiency can be gained. Therefore, with proper designing, maximum efficiency can be attained at any desired load i.e. Copper loss and Iron Loss can be equaled.

• Also read: Transformer Phasing: The Dot Notation and Dot Convention

Good to Know

• Efficiency is usually less than 1 and it is often expressed as a percent (%).
• Ideal Transformer is 100% efficient i.e. the efficiency of ideal transformer is 1.
• Practical transformers efficiencies are generally quite high in compression to other electrical machines and electronics devices (i.e. motors, generators etc) on the ordure of 90 t0 98%.

All Day Efficiency of Transformer

As we know that the commercial or typical efficiency of a transformer is the ratio of Output and Input in watts.

Efficiency = Output (in Watts) / Input (in Watts)

But there are number of transformers whose performance can’t be monitored according the above general efficiency formula.

Those distribution transformers which supply electrical energy to lighting and other general circuits, their primary energize for 24 hours, but the secondary windings does not energize all the time at once. In other words, secondary windings only energize at the night time when they supply electrical energy to lighting circuits. I.e. secondary windings supply eclectic power for very small load or no load for maximum time in 24 hours. It means that core loss occurs for 24 hours regularly but copper loss occurs only when transformer is on load.

• Also read: Difference between Power Transformers and Distribution Transformers?

Therefore, it realizes the necessity to design a transformer in which the core loss should be low. As copper loss depends on load, therefore, they should be neglected. In this type of transformers, we can track their performance only by all day efficiency.

All day efficiency may be also called “Operational efficiency”. On the base of usable energy, we estimate the all day efficiency for a specific time (during the 24 hours = one day). And we can find it by the following formula

All Day Efficiency = Output (in kWh) / Input (in kWh)

To understand about the all day efficiency, we must know about the load cycle i.e. how much load is connected for how much time (in 24 hours).