Substation Auxiliary Power Design Considerations for the Installation of Physical Security Systems

Since the issuance of NERC CIP-014-1 in 2015, utilities across the country have invested significant resources into the hardening of their substations and associated assets to prevent future threats and coordinated attacks resulting in potential extended outages for critical customers ranging from airports and hospitals to corporate headquarters. The installation of enhanced physical security systems at electric substations results in additional electrical loads onto the substation's auxiliary power system. For many substations the addition of these loads and dedicated circuits puts an already strained auxiliary power system into an at-capacity or overloaded situation. Many utilities have not taken into consideration the loading of their auxiliary power system early enough in the design phase as it relates to the addition of an enhanced security upgrade or new installation. The design of the auxiliary power system, whether it is existing or newly upgraded, plays a critical role in the methodology used in a security design. This paper will highlight various design considerations for both utilizing an existing panelboard and station auxiliary power system as well as evaluating designs when a new auxiliary power system is required.