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.

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

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.
95Guidelines for grounding of outdoor high voltage power substation New star.
96Guide to selection of current transformers and wire sizing in substations New.
97Guide to manual and automatic transfer switch equipment New.
98Guide to understanding of earth / ground resistance testing New.
99Safe isolation procedures for low voltage installations New.
100Shunt capacitor bank applications and protection fundamentals New.
101Training report on 33/11 kV substation New.
102Operation and commissioning of 33/11 kV power substation New.
103IEC 61850 standard application examples of substation automation New.
104Selecting and installing a new medium voltage motor control center.
105Construction and Maintenance of High Voltage Power Transformers (For Students).
106Inspection and Test Procedures For Electrical Power Equipment and Systems.
107Design Of Earthing System For (Extra) High Voltage AC Power Substations.
10825 High Voltage Transformer Tests and Commissioning Procedures (Before Energizing).
109Designing a new IEC 61850 substation architecture and solving encountered issues.
110Factory and Site Acceptance Tests (FAT, SAT) For Electrical and Automation Systems In a Power Plant.
111Guide To Medium Voltage Capacitor Bank Switching And Impact Of Overvoltage On The System.
112Measurements Of Transformer Winding Resistance For Diagnostic Purposes.
113Ground Fault Protection Scheme For an Ungrounded Power System.
114Technical Specification Of 11 kV SCADA Controlled Indoor Switchgear (With Interlocking Diagrams).
115Analysis And Implementation Of The IEC 61850 Standard For Substation Automation Systems.
116Substation Event Monitoring Based On IEC 61850 and IEEE 1588.
117Substation Automation Systems Based On IEC 61850 Communications Standard.
118The Concept Of High Voltage Distribution Networks Including Wind Power.
119Design Of 400/220/132 KV 1316 MW Power Substation.
120Transformer Short-Circuit Current Calculation and Reinforcement Solutions.
121Transmission and Substation Design and Operation (Technical Papers).
122Guidelines to properly designed substation grounding system.
123Earth electrode and earth loop impedance testing (Theory and applications).
124Insulation testing using guard terminal (for HV cables, bushings, transformers and CBs).
125Electric power quality in LV grid (Measurements in office buildings and rural substation).
126Fundamentals of HV circuit breakers (applications, failure analysis and maintenance).
127Power Substation Design Course (Parameters and Physical Layout).
128Operation and maintenance of 33/11 kV substation.
129Partial Discharge Analysis in HVDC GIS (Gas Insulated Substations).
130Big data mining and analytics in substation automation and network management.
131SCADA application in Kenyan National Power Grid.
132Operation and maintenance of substation equipment and EHV transmission lines.
133Design study for new 132/33/11 kV power substation in Kingdom of Nepal.
134Design study for 33/11 kV substation, distribution and protection in the city of Kenya.
135Construction & electrical design of 400/220/132 KV power substation.
136Testing and commissioning of 66/33 KV substation.
137Substation equipment maintenance, tests and checkings.
138EHV substation layouts for busbar systems (up to 400 kV).
139Substation data acquisition, automation and control (Future design research).
140Instrument Transformer Calculations and Dimensioning For Substation Protection.
141Synchronising problems in substation protection and automation applications.
142132 KV substation basic training for students.
143New Technologies in Substation Automation Systems.
144Test procedures for large power transformers.
145Wireless sensor network in distribution substation (IEEE 802.15.4 / Zigbee and IEC 61850).
146Best practice in power substation grounding.
147Substation single bus scheme with bus section circuit breakers and interlockings.

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  1. Mphumzi Kleinbooi
    Jan 24, 2019

    Good day sir/madam,
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    Nov 07, 2018

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      Apr 24, 2018

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  9. baseemnasir
    Jan 12, 2018

    Hello dear
    please i want to get the calculation design on a capacitores in electrical substation and and how can we calculate the size of capacitance to instull in electrical power system

  10. Manikandan
    Dec 18, 2017

    How to calculate the substation fault level and what are the inputs are required

  11. vijaya manikanta
    Dec 15, 2017

    Can we consider parallel runs in determining short circuit rating of feeder?

    Example: 33KV incoming feeder has to be designed for 33KV, 31.5KA, 1sec rated Panel to feed 20MW, feeder length is about 2000 m to be laid in RCC Trenches.

    2Runs 33KV, 300 Sqmm, AL Cond., XLPE Cable is recommended to cater 20MW, 350A & fault current of 31.5KA, 1 Sec.

    1Run of 300 Sqmm, AL Cond., XLPE Cable can carry 310A in duct @ 30 deg C and about 28KA for 1 sec as per manf. catalog.

    Considering De-rating Factors for temperature & grouping etc. actual capacity 237Amps/ Run

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    As 2 Runs are considered it is supposed to cater 31.5KA, 1sec considering current sharing in parallel runs.

    Kindly give your advice on the above.

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    Oct 09, 2017

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    May 31, 2017

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    Mar 17, 2017

    Hello, Mr. Csanyi, If you wouldn’t mind, while we are on the subject on the subject of Electrical Software, I would like to hear your opinion on custom software development for power networks. Seeing how the market is dominated by a particular number of companies, can outsiders (IT company) step in and be competitive.

    I’ve recently graduated and now I found myself in this particular business, directly connected with the marketing department. Although I can’t say much about details and particulars (NDA, I’m sure you understand), I work on adaptive coordination for overcurrent relays. I can share link to the particular article (it’s potential customer oriented, not purely technical), discussing the possibilities and advantages of implementing the adaptive OCR.

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    Jan 24, 2017

    This site makes me a better person daily

    Jan 03, 2017


    Please, Can I find books about Photovoltaic systems / Substations?


  18. Faysal
    Dec 31, 2016

    I will be benefited if you assist to know how to calculate HT CT ration for HT/VCB Panel.
    Thanks in Advance ….

  19. Qaisar Jamil Akhtar
    Apr 20, 2016

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  20. 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)?

  21. Saadat
    Mar 26, 2016

    How can i find the book “Substation Commissioning Training Course” written by Mr. Raymond Lee ??
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  22. zaya
    Dec 11, 2015

    Thank you,7

  23. sathish
    Aug 30, 2015

    I’m a substation supervisor in Bangalore.

  24. Nicks Mutuku
    Jul 13, 2015

    This quite helpful. Keep it up.

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

  26. George
    Oct 23, 2014

    how to make electric motor solo run procedure

  27. Elvis Mulowa
    Jul 24, 2014

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  28. 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.

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

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    Feb 16, 2014

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    Jan 19, 2014

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    Oct 25, 2013

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  33. DONDON
    Mar 03, 2013

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

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    Mar 02, 2013

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    Jan 27, 2013

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  36. 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

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  37. Rateb Fares
    Oct 25, 2012

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  38. Jones
    Jun 16, 2012

    kindly provide substation earth mat calculation …

  39. 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

  40. subhransu
    Nov 13, 2011

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    Aug 01, 2011


  42. diamond
    Jul 27, 2011

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