Isc by utility companies

[Toros]

Hi
do you know
why LADWP gives or reports available fault value sometimes more than 50000 amp
but SCE Edison utility company gives 4200 amp maximum

thank yiu

 

[wbdvt]

Without more details, it could be that LADWP is giving a fault current based on an infinite bus and 50kA would be around a 2500kVA txf with a 480Y/277V secondary. SCE could be giving primary available fault current.

Really need more details.

 

[ron]

Con Ed in NYC generally reports 200,000 A on their 208V grid

 

[chris kennedy]

Con Ed in NYC generally reports 200,000 A on their 208V grid

On grid? On tranny secondary bushings?

 

[texie]

On grid? On tranny secondary bushings?

It is common for POCOs the tie the secondary's of multiple transformers together to form a secondary grid. Usually in dense urban areas. The down side is it leads to very high available fault currents.

 

[ron]

On grid? On tranny secondary bushings?

They join XFMR secondary bushings to make grid.

 

[chris kennedy]

Interesting. Never seen that.

 

[ron]

Interesting. Never seen that.

Lots of weird stuff under the sidewalk / street

 

[kwired]

Less liability for them to give someone a high figure in this area than to give a figure that is low, especially if they didn't take the time to actually do the calculations specific to a particular installation.