Battery Power - Summer 2015 - (Page 18)

Feature Protecting Batteries that Protect Your Power System Wally Vahlstrom, Director of Technical Services Emerson Network Power, Electrical Reliability Services According to the US Department of Energy, reported electric emergency incidents and disturbances are on the rise with approximately 23 percent more events reported last year as compared to 2013. These outages or disturbances can cost facilities thousands or even millions of dollars if their emergency power systems do not immediately switch on and provide back-up power. Ensuring that emergency power systems will provide reliable back-up power begins with battery management. Batteries are considered the most critical, yet vulnerable component of emergency power systems. Battery failure is one of the leading causes of back-up power system failure and the resulting outages and losses. Additionally, in the event of a power outage, a single bad cell in a string can leave a facility's critical processes without protection. Despite having this knowledge, many users do not have a proactive battery management strategy in place. Following are some key strategies and best practices that should be considered when determining the strategy that is right for your application and business. Strategy 1: Comprehensive Battery Maintenance A comprehensive preventive maintenance program for emergency power system batteries is one of the most cost-effective measures that can be taken to ensure reliability and prevent costly downtime. An effective preventive maintenance program should include regular inspections of batteries and battery charging equipment, thorough and well-documented battery testing, and proactive battery replacement to ensure batteries are capable of doing their job and supporting critical operations when needed. In fact, one Emerson analysis involving more than 450 million operating hours for more than 24,000 strings of batteries revealed that an increase in the number of preventive maintenance visits substantially increased a system's mean time between failures. Preventive maintenance on batteries should be completed according to industry standards like the following from the Institute of Electrical and Electronics Engineers (IEEE): * IEEE 450 for vented lead-acid (VLA) * IEEE 1188 for valve-regulated lead-acid (VRLA) * IEEE 1106 for nickel-cadmium (NiCad) Battery manufacturers often cite IEEE standards and require adherence in order to maintain a valid product warranty. All of these standards provide recommended practices for maintenance, testing and replacement of batteries for stationary applications. They address the frequency and type of inspection or measurements that need to be made to validate the condition of the battery. Inspections The measurements needed such as string/cell voltage or battery float charging current are outlined in the IEEE standards based on monthly, quarterly, and annual inspections. The more frequent the inspection or testing intervals, the better. Gathering data on a more regular basis can be very helpful for trending battery performance and ultimately extending the useful life of these critical assets. Capacity Tests Recommendations for capacity testing of VLA and VRLA batteries are very similar. Both should be tested at installation, during periodic intervals (no greater than 25 percent of the expected service life), and annually when the battery shows signs of degradation or has reached 85 percent of the expected service life. The IEEE standard also suggests that VRLA batteries should be tested when internal ohmic values have changed significantly between readings or physical changes have occurred. For these two battery groups, degradation is indicated when the battery capacity drops more than 10 percent from its capacity on the previous test or is below 90 percent of the manufacturer's rating. For NiCad batteries, capacity/discharge testing should be done within the first two years of service, at five-year intervals, or annually if the previous test shows evidence of excessive capacity loss. Replacement Both IEEE 450 and 1188 recommend replacing the battery if its capacity is below 80 percent of the manufacturer's rating. And the replacement should be made expeditiously. Physical characteristics such as plate condition or abnormally high cell temperatures are often indicators that the complete battery string or individual cell should be replaced. NERC Standards for Utilities In addition to the IEEE standards, utilities also need to meet battery maintenance requirements stipulated by the North American Electric Reliability Corporation (NERC). NERC's 18 Battery Power * Summer 2015 www.BatteryPowerOnline.com http://www.BatteryPowerOnline.com

Table of Contents for the Digital Edition of Battery Power - Summer 2015

Battery Power - Summer 2015
Table of Contents
Wearable Medical Devices Embrace Lithium Polymer Cells
Five Building Blocks of Self-Powered Wireless Sensor Nodes
Conference Preview: Battery Power 2015
Protecting Batteries that Protect Your Power System
Batteries
ICs & Semiconductors
Components
Chargers
Industry News
Conference Review: Battery Japan 2015
Calendar of Events
Marketplace

Battery Power - Summer 2015