Switchyard main bus sizing in one and half breaker scheme

Could you provide the one line diagram for this scheme?

It would greatly help iin the analysis.

main bus one and two shall be 3000amp, bay bus 2000amp.all bay breakers disconnectors 2000amp.this is standard design.

attached please find the single line diagram for the same.

cleaer veiw of single line diagram is required

Although several other considerations have to be taken into account in sizing the main busses, a simple method is consider total power, take 20% margin on top of that and work out the rating.

In your case, the bus bar may be sized for 3000A.

Short circuit rating needs to be worked out. However, mostly in 400kV system, it works out to be 40kA for 1 sec.

Quad moose conductors or 4" IPS tubes may be selected.

You have to furnish complete details for detailed design.

best wishes

I think with the rating of 3000A, I am oversizing my bus bar. Because if we calculate the power flow diagram under different conditions, No section of the bus will see current more than 1200 Amp assuming that each outgoing line can carry upto max of 600 MW (1200 A) of power.

The different conditions, I mentioned above could be

1) when all lines are healthy

2) Outage of any one line or two line simultaneously.

Busses must be designed for carrying maximum connected load.

Individual feeders are designed based on expected loads connected.

The rating of 3000Amps is adequate for the busses.

However, you can select single or twin moose or any other conductors for line bays depending upon the maximum current required.

Our practice in our utility company is to size the main bus bar at full capacity plus 10% (ultimate design). This works out well with our local weather. However, localities of usually higher than 34 deg Celsius temperature may require bigger sized conductors.

Individual bays are sized at their individual full capacities also.

We sometimes overload our systems, but not more than 10% and 1 hour continuously.

Can u kindly calculate the main bus bar and individual bay current rating?