[NTYNUT (OP)]

Hello
What is one/single line diagram how to draw it
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[evan_au]

What is a Single Line Diagram ?

Homework?

[evan_au]

A single line diagram is a high-level overview of a three-phase electrical network.

It focusses on power generated and power consumed (which must always be equal), and ignores:
- The fact that there are three phases in an AC system
- Voltage and Current in each phase
- An earth wire may or may not be present (star or delta, respectively)
- Often a tower will carry two independent three-phase circuits (6 wires), to assist maintenance
- Geography

Instead, it focuses on:
- the product of Volts and Amps when they are in-phase: VA (or Millions of Volts x Amps = MVA), which could be considered a measure of AC power
- the product of Volts and Amps when they are at 90° Phase: VAR (or Millions of Volts x Amps Reactive = MVAR), which could be considered a measure of wasted AC power (it must be carried, causes load on the network, but it delivers no real energy)
- The generators of this power
- The consumers of this power
- The boxes in-between that let you control this power (circuit breakers, power factor correction devices, etc).

See: https://en.wikipedia.org/wiki/One-line_diagram

[NTYNUT (OP)]

Hello
What is triangle in it?
and why we make Single line diagram in substation

[evan_au]

What is triangle in it?

The triangle is an arrow showing the direction of power flow (and flow of VARS) from generator (sine wave in a circle) towards the load (lines going off the diagram). The arrow is shown more clearly in the Wikipedia article.

why do we make Single line diagram in substation

A single-line diagram is a useful overview of a substation or a whole network.

In a substation, it helps experienced operators to see at a glance:
- how to set voltage ratios on transformers
- Whether you need to turn on power factor correction, and how much
- how to share power between different transmission lines, so they don't get overloaded
- whether part of the substation is shut down for maintenance
- if some part of the network is drawing unusually high power
- when some fault has occurred:
     - where the fault is located
     - what has shut down because of the fault
     - whether some equipment is now overloaded because something else shut down
     - how to route power around the fault
- etc etc.

A Single Line Diagram is like a dashboard for the substation.

The power Engineer's Lament
What annoys electricity operators about solar cells is that it obsoletes all their network diagrams.
- In the "good old days", you knew where your generators were, and you knew where your load was, and you could control the load by controlling the generators. There was a known voltage drop across the substation.
- These days, sometimes the load is a generator, and the transmission line towards the generator is a load, and you can't ring up all those houses to control the generation. Now the voltage drop across the substation sometimes translates into a voltage increase, and the whole network is becoming impossible to manage like it was in the "good old ways" (or so it seems).
- Electricity transmission operators and retailers need to get out a mindset that "we have the power" to one where "we are sharing power". This "democratization" of a critical energy resource represents a significant power shift in the economy.

[NTYNUT (OP)]

Hello
I found this single line diagram can you explain it in details