By Bhavesh S. Patel
Good power quality is extremely important in “high-tech” facilities such as data centers, hospitals, and manufacturing plants, as well as in “low-tech” facilities such as government buildings and commercial enterprises with limited tolerance for electrical disturbances.
Compromised power quality can have costly repercussions, ranging from premature aging/damage of equipment to reduced productivity and interference with business as usual. Common causes of variations in power quality include voltage sags, spikes, and swells, short and long interruptions of power lasting from a few milliseconds to 2+ seconds, and harmonic disturbances.
Facilities vested in good power quality can take advantage of power quality monitoring systems that, operating 24/7, use hardware including sensors and meters to measure electrical sensitivity, software to record and interpret the data, and wired and wireless communications to inform management about what went wrong that affected power quality and where in the electrical system it happened. Power quality monitoring also can keep tabs on a facility’s emergency/backup and/or standby power system.
Where good power quality and operational continuity are critical, facility professionals benefit from the focus of a dedicated critical power management system (CPMS) that complements a building management system (BMS). A BMS aggregates data from all engineered systems in a facility but, operating on a narrow bandwidth, lacks the speed necessary to monitor multiple microsecond changes in the electrical system. In contrast, a CPMS, which operates at a high bandwidth and high speed, typically monitors data from the point utility power enters the facility and forward and looks and analyzes the operation and status of the electrical components of the normal power and emergency power systems.
A sophisticated CPMS can cache or share large amounts of data from one device to another. (Very high rates of speed are required to generate such power quality details as wave form capture or transient harmonic displays.) A BMS and a CPMS can work together to optimize the benefits of monitoring power closely. For example, a CPMS may send automatic alerts on system operation via pager, e-mail, or selected system alarms to the BMS.
Monitored components of a full featured CPMS usually include transfer switches and generator paralleling control switchgear; circuit breakers, bus bar of the normal power system, gensets, loadbanks, and components of the UPS. The system can monitor normal and emergency voltages and frequency, current, power and power factor, and indicate transfer switch position and source availability. It can also monitor the status of both the utility power and on-site power from multiple points of access. Web-enabled communications can provide access to any/all of the information from anywhere in the world.
Here are six benefits of sophisticated power quality monitoring:
1. Early detection of an incipient problem. Awareness of a problem early on, before it escalates and when it is easy to address, minimizes the likelihood of costly interruptions to operations and, possibly, avoids the need for emergency repairs during inconvenient times.
2. Power quality analysis that takes advantage of continuously recorded waveforms that can identify such anomalies as power outages, sags and swells, and transient harmonics, cycle by cycle in milliseconds, can compare current operating parameters of electrical equipment against the manufacturer’s baseline to detect any anomalies that could lead to inefficient operation or failure. The ability to review stored, continuously recorded waveform helps in the diagnosis of problems before an unwanted event recurs.
3. Power quality analytics also supports forensics, allowing management to determine how a chain of events occurred as it did, such as why a facility lost a particular breaker that tripped the PDU (power distribution unit) and resulted in a switchover to the UPS. Power quality analytics could, in that scenario, pinpoint what the root cause was – e.g. a short, an electrical spike, or a floating ground. It can also pinpoint power quality problems that can prematurely age equipment.
4. Power quality analysis can also be used for pre-function testing to look closely at systems and their responses and to simulate transients and other events. Historical records become a baseline that can be compared to equipment and component performance over time, enabling detection of performance trends that can be interpreted to enhance preventive maintenance programs, predict future power requirements, and aid in plans for additional electrical equipment, such as servers or variable frequency drives to control energy costs.
5. A CPMS may include the ability for testing to comply with regulatory reporting requirements. For example, specific reports can help meet various requirements such as the National Fire Protection Association’s NFPA 70, NFPA 99, and NFPA 110. May also include testing to ensure everything in the emergency/backup power system is operating as it was designed and constructed to, even when facilities are not required to perform periodic emergency power testing.
6. Bolstering reliability and efficiency of a facility’s power infrastructure results will help uphold customer and occupant perception of reliable service and help sustain good relations with these stakeholders.