To read & understand control & protection drawings of electrical installations e.g Electrical Grid Station/ Sub-station

Home Electrical Engineering Forum General Discussion To read & understand control & protection drawings of electrical installations e.g Electrical Grid Station/ Sub-station

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    Facing difficulty in this regard, please advice me how to solve this problem.


    Please read the book in electricalengineering drawing (about drawing) More information & Legible drawing is available


    There are different groups of drawings e.g. (i) Interconnection Diagrams and (ii) Schematic Diagrams

    The Interconnection Diagrams usually explain how a cable is connected on both ends or how does it interconnects two equipments?

    All cables are primarily identified from its given identification number and if it is multi core cable, each core is either identified by numbering or by colour coding. An interconnection drawing very well shows the terminal blocks where its cores are to be terminated. This can be found in Cable Schedule indicating where both ends of a particular cable are connected. These drawings also show clearly the terminal blocks with their location in the equipment / panel. These drawings are easy to read.

    The schematic drawings show the whole scheme of a particular circuit (or even the whole grid station). For example a schematic diagram for closing circuit of a circuit breaker  will show the all elements (showing conditions for closing) in the circuit. Those elements may be placed in different equipment or panels. First thing is to understand location of such elements, it is usually marked with different shapes indicating particular equipment or a panel and number of terminal  of that particular terminal block in the terminal box.  Second important thing is to read the schematic diagram in the direction of flow of current in a circuit. It is further advised to start reading a diagram from LEFT upper corner and proceeding downwardly reaching to the lower RIGHT corner of the drawing (as we read any English written page of any book). Thirdly, understand the drawing elements like how the normally close / open contacts, coil of a contactor are shown. What shape represents CTs & PTs, circuit breakers, isolators, lightning arresters etc?

    If Mr. Mushtaq, the initiater of this topic, lives near by Lahore, I may offer my services to let him learn how to read these drawings in just a one hour sitting.


    it needs you supply more information of the grid system what you need protection. Maybe you can find some information from this website:


    it always better to consult different books on the

    Electrical Engineering Reference Manual for the PE Exam, 5th Edition.


    hi friend.. i will give you some articles…i am sure it will help you to read an electrical drawing..

     electrical drawing standard symbol



    there are several types of drawing in sub-station


    1. Single line diagram : which shows No.bays and bus-bar arrangement.

    2. Protection and metering single line duagram : which shows you how the your bays are protecting with diffrent tpye of faults and deatils of your breaker tripping and closing coil assignment for tripping.

    3. Schematic drawings with interface : which show you panel wiring with interpanel connection

    Only main thing is you need understand is how to read

    1. first page of any drawing is index/contents

    2. second page contain legends of symbol : Here you need to go through each and every symbol representation and other presentation


    presentation of terminals -X1:1 ( X1 represents terminal block label and 1 terminal number)

    presentation of component and contacts of the coil given exactly below or side of same page drawing from there you can identify the no of normally open and normally close contacts assigned some definate function

    presentation of sheet to sheet reference eg: _ _

                                                                      -k1 / 4G2

           k1 is component name you can find that that component in the sheet 4 ( each and every sheet is devided in row and clolumn, rows are represented by alphabetical character and column are represented by numbers) G row 2nd column, The above contact is normally open when the respect coil energized this contact will close.


    please send me your mail ID, insha allah i will share my knowledge                                                         


    Components used for making a electrical control circuit and its standard symbols.

    Push buttons.
    Pilot lights.

    how to read electrical drawings? it is very simple. first of all we want to know abt the symbols used. read the below articel

    learn to read electrical drawing

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