Synchronous Generation and System Fault Current Limitations

When a fault or short-circuit occurs in an electric power system, all synchronous generators contribute current until protective equipment acts to either isolate the fault or trip (switch off) the generators. If the fault current exceeds equipment’s ability to protect the system, the result could be a catastrophic failure of the equipment, as well as significant portions of the electric system infrastructure.

The fault current contribution of any local generation that uses synchronous generators must be considered prior to the acceptance and approval of your application. There are several options that may be available, depending on your choice of local generation configuration:

  • Reduction of total aggregate synchronous generation at the site to an acceptable level
  • Use of alternative generation strategies, such as induction or DC inverted generators
  • Use of an “AC-to-AC DC Link” product, in which the electric conversion equipment would also minimize the generator’s fault current contribution
  • Use of a “Fast Fuse” or “Power Fuse,” which acts to rapidly trip your generator within an acceptable time limit

There may be additional options available, depending on your choice of local generation equipment and the electric system infrastructure near your proposed site. These options can be explored and evaluated through discussions with the local generation experts at Con Edison.

To check availability, choose the borough where your proposed local generation installation is located.

Fault Current Maps by Borough

Bronx (PDF)
Brooklyn (PDF)
Manhattan (PDF)
Queens (PDF)
Staten Island (PDF)
Westchester (PDF)