short circuit calculation with motor contribution

[hhsting]

Does anyone know of free good calculator or free software for short circuit fault current calculation and gives motor contribution also? I have POCO xfmr fault current secondary

 

[mayanees]

I do not know that such a program exists, but if you post the info or PM me I'll run the calc for you.

 

[hhsting]

I do not know that such a program exists, but if you post the info or PM me I'll run the calc for you.

Ok here goes:

Poco secondary xfmr 65ka fault current. 208/120V three phase. Need short circuit calculation following points:

1. Switchboard: located 14 feet away from POCO transformer secondary 65kA fault current. Service entrance cable 9 sets of 500kcmil AL direct buried.

2. Panelboard DP: located 75 feet from switchboard with direct buried 4 sets of 350MCM AL

3. Meterstack 1: located 142 feet from panel DP with feeder 2 sets of 500 MCM AL in conduit

4. Meter stack 2: located 149 feet from panel DP with feeder 2 sets of 500 MCM Al in conduit


What are the fault currents at above 4 points?

 

[winnie]

Ok here goes:

Poco secondary xfmr 50kA fault current. 208/120V three phase. Ineed short circuit following points:

1. Switchboard: located 14 feet away from POCO transformer secondary 50kA fault current. Service entrance cable 9 sets of 500kcmil AL direct buried.

2. Panelboard DP: located 75 feet from switchboard with direct buried 4 sets of 350MCM AL

3. Meterstack 1: located 142 feet from panel DP with feeder 2 sets of 500 MCM AL in conduit

4. Meter stack 2: located 149 feet from panel DP with feeder 2 sets of 500 MCM Al in conduit


What are the fault currents at above 4 point?

I don't have the software, but I know that if you want to include the motor calculation you will need to provide the motor specs....

*grin*
Jon

 

[hhsting]

I don't have the software, but I know that if you want to include the motor calculation you will need to provide the motor specs....

*grin*
Jon

For now regular fault current calculation. I need to compare what is regular with what is provided in plans

 

[Dsg319]

Does anyone know of free good calculator or free software for short circuit fault current calculation and gives motor contribution also? I have POCO xfmr fault current secondary

Not sure if the bussman app does?

 

[hhsting]

Not sure if the bussman app does?

Dont see direct buried cable? Only raceway

 

[jim dungar]

Does anyone know of free good calculator or free software for short circuit fault current calculation and gives motor contribution also? I have POCO xfmr fault current secondary

Have you looked at the calculator from Schneider Electric? It can handle motor loads.

Fault Current Calculator

Use PVC (non-metallic) conduit for direct burial applications.

 

[mayanees]

Ok here goes:

Poco secondary xfmr 65ka fault current. 208/120V three phase. Need short circuit calculation following points:

1. Switchboard: located 14 feet away from POCO transformer secondary 65kA fault current. Service entrance cable 9 sets of 500kcmil AL direct buried.

2. Panelboard DP: located 75 feet from switchboard with direct buried 4 sets of 350MCM AL

3. Meterstack 1: located 142 feet from panel DP with feeder 2 sets of 500 MCM AL in conduit

4. Meter stack 2: located 149 feet from panel DP with feeder 2 sets of 500 MCM Al in conduit


What are the fault currents at above 4 points?

Do you have motors?

 

[mayanees]

Do you have motors?

That's using non-magnetic conduit. If magnetic conduit is used for the runs to the meter stacks, the fault current levels drop below 18 kA.

 

[augie47]

I would suggest that you proceed down this road very carefully from a liability standpoint.
These numbers should be developed by an engineer. As a plan review person, if you start "engineering" to confirm the numbers and the is an error you might be opening your self up to liability.

 

[topgone]

Do you have motors?

Good question. If I may add, disregard motor loads under 50HP in the calculations for fault contribution.

 

[MyCleveland]

Good question. If I may add, disregard motor loads under 50HP in the calculations for fault contribution.

Is this not acceptable for MV applications only.

 

[mayanees]

I would suggest that you proceed down this road very carefully from a liability standpoint.
These numbers should be developed by an engineer. As a plan review person, if you start "engineering" to confirm the numbers and the is an error you might be opening your self up to liability.

I am an engineer, licensed in the state that hhsting resides in. He gave me the parameters and I provided the calculation.
But, to your point, I don't expect hhsting to use my 5-minute fault current calculation to make design decisions. There are numerous parameters that go into the calculation and would need to be verified, like the Utility contribution with X/R ratio (likely not 65kA), the cable length and type, ...

 

[xformer]

Eaton Bussman has a phone app that might be utilized. Its called FC2