NERC’S PRC-005-6 RELIABILITY STANDARD HAS PLACED INCREASED DEMAND ON UTILITIES FOR BATTERY MONITORING AND MAINTENANCE.
AND, IT HAS IMPOSED STRINGENT DATA REPORTING REQUIREMENTS THAT MUST BE MET.
Managing and protecting power system assets has always been an important part of operating an electric power system, but it has also posed some serious challenges. The parts that make up a utility’s Protection System like Protective Relays or communications systems do not typically perform their protective function until a fault or other power system problem demands that they operate to protect power system elements or the entire Bulk Electric System (BES). In fact, lacking any faults or system/operation problems, the Protection Systems may not need to operate at all unless a test is conducted. But when a fault or problem is detected, it is vital that a utility’s Protection System function as it is intended to function. A utility’s Protection System must be reliable and adequate to respond on demand to:
protect utility personnel and
ensure that power customers do not experience disturbances or outages.
Batteries are an important part of a utility’s Protection System, and they play an important role, but like the other parts of the Protection System- they are not called upon to provide power instantaneously and on-demand UNTIL power is required by the Protection System to operate circuit breakers or circuit interrupting devices to clear faults or to protect power system elements.
Utilities often use flooded batteries for backup power in the Protection System because they can hold higher reserve power capacity and because they have a longer life than some other battery options, upwards of 20 years if kept at or near 77°F / 25°C. Because NERC understands that these batteries play an important role in the protection of the power system and that a flooded battery poses a unique dilemma due to the fluid or electrolyte held within the battery and how that electrolyte is affected during the charge and discharge process, they have specified per their required reliability standard: PRC-005-6 that each VLA should meet some very specific 4-, 6-, and 18-month maintenance requirements in order to be in compliance.