The following article describes how transmission transformers are managed in the Pennsylvania–New Jersey (PJM) Interconnection. PJM is a regional transmission organization (RTO) that operates approximately 19% of the transmission infrastructure of the U.S. Eastern Interconnection. As of 2007, there were 188 transmission transformers (500/230 kV) and 29 dedicated spare transformers in the PJM system. A Probabilistic Risk assessment (PRA) model is applied to PJM transformer asset management.

A. What are the potential consequences of running a transmission transformer to failure with no available spare to replace it?

B. What are the benefits of sharing spare transmission transformers among utility companies?

C. Where should spare transmission be located?