• What Is A Single Line Diagram

ELECTRICAL AND ELECTRONICS DIAGRAMS USAS Y14.15 -1966 USA STANDARD APPROVED includes the following: 15-1 Scope 15-2 Definitions 15-3 General Infonnation 15-4 Single-Line Diagrams, General 15-5 Single-Line Diagrams (Electronics and Communications) 15-6 Single-Line Diagrams (Power Switchgear and Industrial Control).

SINGLE LINE DIAGRAM: As a layman View, SLD is nothing but consisting of various components of the Electrical System like, Transformer, DG, Panels consisting of HT Breaker, LT Breaker, CT, PT. The PDF file structure was designed to work while 'online' therefore saving these PDF files to a desktop will cause the bookmarked links to each SLD to be broken. 2019 Straight Line Diagrams (2.2m) (This is the entire SLD including the greeting, terms abbreviations, definitions and enlarged diagram views. The high-voltage winding is rated 69 line to- line kilovolts (kV) and The low-voltage winding is rated 13.8 line-to-line kilovolts. The note, Z=7.6%, indicates that the impedance of the transformer is 7.6%. Unless otherwise noted, the impedance shown on a one-line diagram is based on the transformer’s OA rating.

DC Combiner Panel 3 ###A, ###VDC DC Combiner Panel 2 ###A, ###VDC DC Combiner Panel 1 ###A, ###VDC ##A XYZ Co. Model A Inverter ##kWAC, ###VAC. Single-Line Diagram Development The single-line diagram is the blueprint for electrical system analysis. It is the first step in preparing a critical response plan, allowing you to become thoroughly familiar with the electrical distribution system layout and design in your facility. A typical diagram will include: yyIncoming lines showing voltage.

SINGLE LINE DIAGRAM:

As a layman View, SLD is nothing but consisting of various components of the Electrical System like, Transformer, DG, Panels consisting of HT Breaker, LT Breaker, CT, PT, Fuses, Meters, Capacitor and many on. Also it have HT Cables, LT Cables & Earthing System.

HOW TO READ A SINGLE LINE DIAGRAM:

STEP 1:

First you should know the common symbols used in an sld. Without knowing the symbols, you can neither draw an sld nor read it. Below are the picture of some commonly used symbols.

2nd step:

You should know the common abbreviations used in an sld. Below is the list of few commonly used abbreviations:

EXAMPLES OF SINGLE LINE DIAGRAM:

1) ELECTRICAL POWER SYSTEM NETWORK:

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INTERPRETATION:

1) Electricity is usually generated in the ranges of 11-33kv from different sources at generating station. After that it is stepped up to either 132kv, 220kv, 500kv etc by using step up power transformer. Lets say 132kv

2) After that it is send along transmission lines spread on hundreds to thousands of kilometres. It is received in a station called transmission substation where it is stepped down to lower voltage levels. In the above example it is stepped down to 33kv.

3) It is send to another substation called distribution substation where it is stepped down to 11kv and then from 11kv to 440volts. Industrial consumers are supplied electricity at 11kv and residential consumers at 440volts or 220volts.

EXAMPLE 2:

INTERPRETATION:

1) 132KV is stepped down to 11kv by using a step down transformer which is having configuration as delta star. This configuration is normally used in distribution transformer because there will be 3 lines available at high voltage side and four lines available at low voltage side. So, to provide neutral point to consumer this configuration is used.

2) Then electricity passes through Current transformer and potential transformer. These CT and PT are connected to relay coil( its not shown in picture but it is there). Relay coil will detect the high current in CT and low voltage or voltage drop in PT. As soon as it detects it, it will send signal to circuit breaker and breaker will trip. After tripping of breaker, isolators will open to disconnect remaining circuit from source of supply.

3)Isolator is connected to LT bus bar. This bus bar is connected to feeder which supplies electricity to different areas.

3rd example:

INTERPRETATION:

1) Transformer is feeding power to system. This transformer steps down voltage from 35/15kv. Once voltage is stepped down it passes through to a circuit breaker. CB(a1) is connected to main bus.

2) Two more circuit breaker b1 and b2 are connected to main bus. Attached to CB(b1) is a stepped down transformer which steps down from 15 to kv.

3) On the 5kv side of this transformer( Tx-2), a disconnected switch is shown. This disconnecter switch is used to isolate or connect the equipment below it from transformer.

4) Below isolator two medium voltage motor starter are connected. A number of starters could be connected depending upon system requirements.

5) CB(b2) is connected to a step down transformer(TX-3) and transformer is connected to CB(b3).

6) On left side a generator is connected to automatic transfer switch. This area of one line diagram tells us that it is important for equipment connected below automatic transfer switch to keep on running even from power from bus is lost. This generator is acting as an emergency generator.

7) On right side (section C), another circuit breaker CB(c2) is connected to meter centre. This indicates that the electric company is using these meters to keep track of power consumed by the equipment connected below meter.

What Is A Single Line Diagram

8) Below the meter centre is load centre that is feeding a number of smaller circuits. This could represent load centre in a building that feeds power to light, AC or other electrical equipments connected to building