Fault Current Analysis Motor Contribution
Fault Current Analysis Motor Contribution
(OP)
Hey all,
I am currently performing an arc flash analysis on our industrial plant. Am in the fault current calculation stage but am having trouble dealing with motor contribution. I understand the 4x factor on the FLA of the motor. It's the flow of the available fault current (AFC) from the motor in to parallel branches of the one-line that has me puzzled. What is the best way to incorporate the motor contribution throughout the system?
I was thinking that I could neglect the line impedance seen by the motor contribution (mc) and sum all the mc current values upstream to the utility. Add the total mc current to the utility AFC, and then carry that value downstream degrading it due to impedances of the lines and transformers. Does this seem like a valid method? Or is there a better way.
Unfortunately, I don't have fancy software, just using the one-line and a custom spreadsheet.
Thanks for any help you can offer!
I am currently performing an arc flash analysis on our industrial plant. Am in the fault current calculation stage but am having trouble dealing with motor contribution. I understand the 4x factor on the FLA of the motor. It's the flow of the available fault current (AFC) from the motor in to parallel branches of the one-line that has me puzzled. What is the best way to incorporate the motor contribution throughout the system?
I was thinking that I could neglect the line impedance seen by the motor contribution (mc) and sum all the mc current values upstream to the utility. Add the total mc current to the utility AFC, and then carry that value downstream degrading it due to impedances of the lines and transformers. Does this seem like a valid method? Or is there a better way.
Unfortunately, I don't have fancy software, just using the one-line and a custom spreadsheet.
Thanks for any help you can offer!






RE: Fault Current Analysis Motor Contribution
RE: Fault Current Analysis Motor Contribution
RE: Fault Current Analysis Motor Contribution
Hand calculations for systems like this (more than 10-15 buses) are usually not done anymore; look at software packages.
RE: Fault Current Analysis Motor Contribution
What he said. You need one of the software packages designed for this purpose. Do a search on this forum for system analysis software.
RE: Fault Current Analysis Motor Contribution
RE: Fault Current Analysis Motor Contribution
I guess I'll have to tough it out and figure out a way to deal with it! Thanks for the tips, all.
RE: Fault Current Analysis Motor Contribution
RE: Fault Current Analysis Motor Contribution
RE: Fault Current Analysis Motor Contribution