Dear
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
like
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.
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