Power Substations HV/MV/LV Guides
Power Substations HV/MV/LV 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.

The first substations were connected to only one power station where the generator was housed, and were subsidiaries of that power station.

Equipment in substation

Substations generally have switching, protection and control equipment and one or more transformers. In a large substation, circuit breakers are used to interrupt any short-circuits or overload currents that may occur on the network. Smaller distribution stations may use recloser circuit breakers or fuses for protection of distribution circuits. Substations do not usually have generators, although a power plant may have a substation nearby.

Other devices such as power factor correction capacitors and voltage regulators may also be located at a substation.

Substations may be on the surface in fenced enclosures, underground, or located in special-purpose buildings.

High-rise buildings may have several indoor substations. Indoor substations are usually found in urban areas to reduce the noise from the transformers, for reasons of appearance, or to protect switchgear from extreme climate or pollution conditions.

Where a substation has a metallic fence, it must be properly grounded (UK: earthed) to protect people from high voltages that may occur during a fault in the network. Earth faults at a substation can cause a ground potential rise. Currents flowing in the Earth’s surface during a fault can cause metal objects to have a significantly different voltage than the ground under a person’s feet; this touch potential presents a hazard of electrocution.

All documents, EE software and EE books are free to download.

1Answering Substation Automation Questions Through Fault Tree Analysis
2Applying an Ethernet LAN in a Substation
3Power Plant Accoustic
4Power Transformer Maintenance And Acceptance Testing
5Selecting Energy Efficient Distribution Transformers
6MV-LV transformer substations – theory and examples of short-circuit calculation
7Electric Power Substations Engineering
8Implementation of IEC61850 in a Substation Environment New
9Design Guide for Rural Substations New
10Guide To Forms Of Separation In LV SwitchGear and ControlGear – UPDATED! New
11Factory Acceptance Test (FAT) procedure
12Best Practice Manual For Transformers
13Schneider Electric – Low Voltage Switchboard Inspection Guide star
14Difference Between Switchgear and Switchboard star
15Protection of Electrical Networks star
16Technical Guideline For Interconnection Of Generators To The Distribution System
17Power transformer – testing procedures
18Electric Power Applications, Engine and Generator Sizing
19Megger – Fault Finding Solutions star
20Electric Distribution Load Characteristics
21Power Plant Practices to Ensure Cable Operability star
22Substation Design Application Guide star
23XLPE Underground Cable Systems star
24Guidlines for substation service inspection & condition monitoring star
25Using of Latched Contactors to Switch Transformers
26INSTRUCTIONS – Installation, Operation, and Maintenance of Medium Power Substation Transformers
27Uninterruptible Power Supply (UPS) Types
28High Voltage Techniques Course star
29Real-time Monitoring and assessment of CB operations for diagnostics and control applications
30Capacitor Application Issues New star
31Medium Voltage Switching Devices Selection for application and purpose
32Preventive maintenance and reliability of LV overcurrent protective devices New
33ABB – SF6 or Vacuum MV Circuit Breaker? star
34Why Is Arc Detection Important? star
35DC Transmission and Distribution star
36Underground Power Transmission Lines New star
37Test Guide for Cast Resin Dry Type Transformer – TRIHAL star
38Low Voltage Switchgear and Controlgear – Technical Document (Allen-Bradley)
39Transformer Differential Protection Scheme With Internal Faults Detection Algorithm
40Grounding Systems
41Insulator Pollution In Transmission Lines
42Transformers Basics, Maintenance and Diagnostics
43Guidelines For Earthing In Maritime Installations – Norwegian Electrical Safety Directorate
44Fixed or withdrawable MV switchgear? star
45Power System Earthing Guide star
46Ground Fault Protection Technical Guide star
47Introduction to IEC 61439 – A new standard on Switchgear and Controlgear Assemblies
48Commissioning of HT Electrical System star
49Electrical design of the on-site generation system star
50Safety operations on medium voltage switchgear star
51Mitigate The Magnetic Field Exposure Near Transformer Substation
52General Technical Specification For 220kV SF6 Gas Insulated Metal Enclosed Switchgear (GIS) New
53Measuring Earth Resistance star
54National Electrical Code design considerations as applied to Utility Substations
55A Practical Guide To Earth Resistance Testing New star
56Load Shedding For Utility and Industrial Power System Reliability
57Energy Transmission and Distribution Guide
58Improving safety on ageing switchgear New
59Technical Considerations in the Specification and Design of LV Switchboards New star
60The 21st Century Substation Design New star
61Switchgear and Motor Control Centres in Oil, Gas and Petrochemical Industry
62Low voltage switchgear and controlgear application guide for electrical engineers
63Static Analysis of Power Systems New
64Practical guide to electrical measurements in LV switchboards – ABB
65Power System and Substation Automation Guide
66Reliability of Substation Configurations star
67Substation Design Guideliness star
68Power Transformer Maintenance and Field Testing star
69Selection of CTs and wire sizing in power substations star
70Copper for Busbars – Guidance for Design and Installation star
71Thermal design of MV/LV substations star
72Guidelines for Conducting an Energy Audit in Industrial Facilities star
73Transformer Protection Application Guide star
74Instrument Transformers Application Guide
75How to assemble LV electrical switchboard – Technical guidestar
76A Guide To Power Factor Correction For The Plant Engineers star
77Complete Guide To Wind Power Plants New star
78Design of Electrical Power Supply System in an Oil and Gas Refinery
79Guidelines to Power Transformer Type, Routine and Special Tests
80Guidelines to the construction of a low-voltage assembly
81Guide to High Voltage Direct Current (HVDC) Transmission New
82Design Manual For High Voltage Transmission Lines New
83Power Plant Horror Stories – The Loss Of a Generator
84Electrical Design Of 132/33KV Substation star
85Operation and Maintenance of a 220/132KV Substation star
86Design and construction of long-distance HV transmission systems New star
87Development of 22kV Distribution Systems and Switchgear star
88Electrical Safety Hazards Handbook star
89Complete Guide To Diagnostic Insulation Testing Above 1 kV star
90Transfer Switch Application and Selection Manual star
91Guide to Low Voltage Circuit Breakers Standards star
92Battery Maintenance and Testing Guide New star
93Design Guide For Overhead Distribution Systems New star
94Guide to MV/LV transformer substations (2000 kVA or two 1000 kVA) New star

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Page edited by E.C. (Google).


  1. Qaisar Jamil Akhtar
    Apr 20, 2016

    Hi, i study your E E portal, That is good attempt to convey your syetem specs to Readers, pls i need substations details on my Email site.

    Thanks & Regards

  2. hossein
    Apr 05, 2016

    Hello my Friend.Could we omit the GCB(Generator Circuit Breaker) of a 160MW Combined Cycle unit (with a 160MW/15.75kV Genarator and a 200MVA/230/15.75kV Unit Transformer)?

  3. Saadat
    Mar 26, 2016

    How can i find the book “Substation Commissioning Training Course” written by Mr. Raymond Lee ??
    It is very Urgent.
    Thank you.
    My email:

  4. zaya
    Dec 11, 2015

    Thank you,7

  5. sathish
    Aug 30, 2015

    I’m a substation supervisor in Bangalore.

  6. Nicks Mutuku
    Jul 13, 2015

    This quite helpful. Keep it up.

  7. Using Voltage Stabilizer and UPS systems can prevent you from any kind of power mishaps.

  8. George
    Oct 23, 2014

    how to make electric motor solo run procedure

  9. Elvis Mulowa
    Jul 24, 2014

    thanks for the good works we are really updated

  10. letlhogonolo mogorosi
    Mar 27, 2014

    I am working as a technician in eskom, i like knowing about different protection we found in our substation,different relays how they operate when flacked what fault to be expected.more especially in distribution substations.i hope ill learn a lot from you thanks.if posible can you send me theorytical guardes.

  11. AIDIL ARIFIN, E Eng.
    Mar 21, 2014

    Thanks & Regards,

  12. B.Venkat Reddy
    Feb 16, 2014

    Excellent Technical Knowledge Site, I Like Very much and Many Thanks for providing such useful technical paper, keep the good works.

  13. cristian
    Jan 19, 2014

    Thanks for your documentations ,my job is electrical technician ,vendor position for italian provider LV & MV electrical equipment.


  14. Aljan24uson
    Oct 25, 2013

    Thanks for this kind of portal site. It is very informative and helps a lot to our fellow electrical practitioners….keep it up guys!!!

  15. DONDON
    Mar 03, 2013

    Can anyone show me the Fault Current Calculation of Transmission Lines?

  16. namnguyen
    Mar 02, 2013

    Thanks for useful technical paper, keep the good works.

  17. alhana89
    Jan 27, 2013

    Thanks for making these references available for us. Keep up the good work, guys!

  18. lollo
    Jan 08, 2013

    Hi the people iv just finished my studies and am currently working,and I have been learning on how to use the new software “Janitza GridVis software” and this software monitors power from High to Low voltage systems and currently i have been tasked yo write a programm that will be used for valves have any of you people got maybe some idea on this new jasic programming??

    • Edvard
      Jan 08, 2013

      To be honest I never heard of it. Can you share with me some information about it, some links.

  19. Rateb Fares
    Oct 25, 2012

    thank you very much

  20. Jones
    Jun 16, 2012

    kindly provide substation earth mat calculation …

  21. engrwaqas_11
    Nov 20, 2011

    thank you very much for such nice work..if possible please upload field testing date e.g. transformers testing, under ground cable testing, relays testing..etc


    Waqas Ahmed

  22. subhransu
    Nov 13, 2011

    want to be a part of this knowledge pool. Help me out.

    Aug 01, 2011


  24. diamond
    Jul 27, 2011

    thanks a lot

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