Embracing NERC PRC-005-2 Compliance

NERC PRC-005-2, the new standard developed by the North American Electric Reliability Corporation (NERC) for bulk power systems, went into effect last year. Here is a look at what makes this standard so unique and some tips on how best to comply.

By George Brendahl, Marketing Manager, Utilities and Nuclear, EnerSys

NERC PRC-005-2, the new standard developed by the North American Electric Reliability Corporation (NERC) for bulk power systems, went into effect last year. Here is a look at what makes this standard so unique and some tips on how best to comply.

Effective February 2014, NERC PRC-005-2 defines maintenance and monitoring activities for substation batteries. It is different from other industry standards, such as IEEE, in a number ways.

NERC PRC-005-2 Adds Enforceable Time Frames
The standard requires battery inspections every four months. Every 18 months, it requires additional testing, such as float voltage, battery continuity, battery terminal connection resistance and battery intercell/unit-to-unit connection resistance. The standard also requires internal ohmic value testing every 18 months or battery capacity testing every six years (as per IEEE 485). It is our experience that, while some utilities may monitor to these standards, many do not record data with this frequency. As such, many utilities now are reevaluating and, in some cases, altering their current battery maintenance procedures, such as using automated monitoring and data collection.

A benefit of the NERC maintenance requirements is that, for the first time, it can reveal trending information in as little as a month. This is especially true if the utility is using an automated testing system. For while technicians only may visit a substation once or twice a year, an automated system can check measurements every day, several times a day. As such, it can take a technician up to a year to identify a potential problem with a battery, whereas the same problem may be identified in as little as a month using an automated system. The latter allows technicians to correct the problem immediately, potentially extending the life of the battery.

At the same time, trending data may cause some concerns for utilities. For example, it may be difficult to identify if a shift in float voltage is a natural occurrence or an indication of a problem. Since many utilities have not seen trending data like this before, it may be hard to know the difference. Battery manufacturers can serve as a good resource here, helping utilities weed through this “noise” of data.

NERC PRC-005-2 Allows Flexibility in Performance Testing
The NERC regulations allow utilities to choose either the NERC internal resistance tests or the IEEE capacity test. From a battery manufacturer’s perspective, the standard should require both, as the capacity test is a more reliable indicator of battery health.

Voltage is not nearly as reliable, as it doesn’t account for potential voltage migration. It is important to realize that voltage migration is not necessarily an indicator of failure; some batteries just may be performing better than others.

Performance under load puts the spotlight on actual response to the demand load. As a battery manufacturer, we strongly recommend that utilities employ capacity testing to check performance under load. Many variables can impact performance under load, such as environment or changes in the grid, making it difficult to pinpoint which ones are causing a battery failure indication. A seasoned technician can be invaluable in this situation. However, with fewer experienced technicians in the field, utilities will be well served to work closely with the battery vendor directly. Ideally, the utility should work with the manufacturer of the installed batteries rather than a competitive manufacturer, as the manufacturer of the installed batteries may be more likely to seek a solution to the problem, rather than simply replacing the battery.

NERC PRC-005-2 is enforceable by the Federal Energy Regulatory Commission (FERC).
Under NERC PRC-005-2, utility owners are responsible for not just monitoring but also analyzing data, recognizing when a disparity means a problem and determining whether corrective action is needed -- at the risk of facing sanctions from the FERC.

This is not an easy task. The NERC PRC-005-2 Standard is a daunting 40-page document that specifies what measurements are required, but not how to do them for optimum accuracy. There also is no guidance to indicate compliance with the standard. This puts a tremendous burden on utility management to consistently deliver accurate results -- all while coping with a dwindling work force of seasoned technicians and the natural effects of human variance and error.

Here again, some utilities are turning to automated systems to facilitate compliance with NERC PRC-005-2 and to gather the necessary data to evaluate their batteries. With an automated system, the measurements are taken exactly the same way each time.

As for guidance, battery manufacturers can be of invaluable help to utilities in establishing performance limits, determining the best test data to collect, interpreting this new data and recommending the best corrective actions. In this way, battery manufacturers can help utilities realize the complete value of their data, ensuring that the utility achieves optimum battery performance and reliability under the new NERC standard.

For more information, including a supplementary reference guide and FAQ on NERC PRC-005-2, visit http://www.nerc.com/pa/Stand/Pages/PRC0052RI.aspx.

EnerSys, the global leader in stored energy solutions for industrial applications, manufactures and distributes reserve power and motive power batteries, battery chargers, power equipment, battery accessories and outdoor equipment enclosure solutions to customers worldwide. Motive power batteries and chargers are utilized in electric forklift trucks and other commercial electric powered vehicles. Reserve power batteries are used in the telecommunication and utility industries, uninterruptible power supplies, and numerous applications requiring stored energy solutions including medical, aerospace and defense systems. Outdoor equipment enclosure products are utilized in the telecommunication, cable, utility, transportation industries and by government and defense customers. The company also provides aftermarket and customer support services to its customers from over 100 countries through its sales and manufacturing locations around the world.

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