Rationalizing an investment in a facility's infrastructure can be a difficult prospect, often requiring an extensive justification—especially if your facility is owned by the federal government. Investments that are deemed "low risk" and have a fast return on investment (ROI) are typically the simplest to substantiate. One such investment that will pay considerable dividends over its operating life is a comprehensive power monitoring system.
Increased energy prices are already exerting a substantial influence on the balance sheet than in years past. Federally owned facilities, however, have an additional challenge: to meet energy efficiency mandates. The Energy Policy Act of 2005 (EPAct 2005) and the Energy Independence and Security Act of 2007, for example, affect the energy efficiency of federal buildings. Essentially, this legislation requires all federal government facilities to reduce energy consumption by 3% per year through 2015 for a total 30% reduction. Additionally, EPAct 2005 requires facility managers to develop a metering plan for their building and install advanced electric meters on all federal buildings by October 1, 2012.
Without power monitoring systems in place, federal building facility managers will likely have only a vague understanding of their building's energy usage, making it much more difficult to meet established energy efficiency and energy management mandates. In addition, many facility managers who do have power monitoring systems in place are not using them to their fullest potential. To optimize an investment in a power monitoring system it is important to understand both the intended application and the energy usage priorities within a given facility. This article lists key questions to consider when choosing a power monitoring system for a federal facility or when reassessing an existing power monitoring system.
Why Install a Power Monitoring System?
A properly designed and installed power monitoring system provides federal facility managers with a deeper understanding of the operational parameters of the facility's electrical system, along with securing energy mandate compliance. A close appraisal of the data generated by a monitoring system can reveal a variety of overt and subtle opportunities for the end user bent on decreasing energy consumption:
- Environmental—A better knowledge of how energy is used within a facility allows management to identify an array of prospects to improve efficiency, minimize waste, and reduce energy consumption, thereby allowing the facility to meet mandated energy efficiency targets.
- Reliability—Assessment of data from the monitoring system can reveal existing or imminent problems that can negatively affect a facility's operation. Historical data from power monitoring systems can help locate and correct both acute and chronic problems.
- Maintenance—Data trends allow forecasting and notifying the end user when discrete equipment parameters may be exceeded, giving the end user an opportunity to proactively plan ahead for electrical equipment maintenance.
- Safety—Monitoring systems can limit the exposure of personnel to potentially hazardous electrical environments by providing remote status and operational parameters of equipment within hazardous areas.
- Financial—Each of the items listed influences a federal facility's budgetary parameters, either directly or indirectly. In most cases, the monetary savings from even one or two of these benefits can justify the purchase and installation of a power monitoring system.
Additional advantages offered by power monitoring systems may include features such as accurate evaluation of spare electrical system capacity, billing allocation and validation, and optimum placement of mitigation devices. When deployed properly, power monitoring systems can accurately quantify energy usage, even down to the level of discrete components. This capability allows facility managers to more effectively target and address equipment that is operating below a predetermined energy efficiency threshold.
What Monitoring Equipment Should Be Installed?
A true power monitoring system contains two or more discrete metering points that are interconnected through some other medium. The three primary components of a power monitoring system include:
- Discrete metering devices to record data
- Software to accumulate, manage, and display the data
- A communications interface between the software and metering devices
The monitoring system components should be compatible with each other to ensure that the greatest benefits are realized from the system. There may be other ancillary components, but these are defined by each specific power monitoring system's requirements.
A wide array of metering devices is available commercially. The devices come in all shapes and sizes, ranging from the basic to the complex. Selecting an appropriate metering device requires an understanding of both the intended application and the goals for the entire power monitoring system.
Mid-range metering devices, such as the Square D PowerLogic PM800 power meter (Figure 1), generally provide basic measurements including voltage, current, real and reactive power, power factor and energy usage. These have an economic advantage but provide less functionality and flexibility than their high-end counterparts.
Figure 1. The PowerLogic PM800 is a mid-range energy meter that provides basic electrical measurements
High-end metering devices, such as the Square D PowerLogic ION7650 power and energy meter (Figure 2), are more complex and offer a variety of features. In addition to the measurements provided by mid-range meters, high-end devices can perform more sophisticated tasks, such as disturbance detection and location, automated alarm configuration, harmonic distortion analysis, flicker detection and location, high-speed transient detection, and anti-aliasing. High-end metering devices are usually manufactured with components that are intrinsically more accurate than mid-range metering devices; as a result, they are also more expensive. Ultimately, the choice of one device versus another should depend on the intended application of that device or system.
Figure 2. The PowerLogic ION7650 power and energy meter provides basic measurements in addition to more sophisticated measurement and analysis capabilities
Evaluating data from monitoring devices is more easily and efficiently performed with PCs than at the discrete monitoring device. Software allows facility management to view data from discrete devices and also to perform complex analyses at a system level. The software provides a means to log data in low-end devices that lack logging capabilities. It can also be configured to aggregate data across single or multiple monitoring systems. Finally, the end user can also view alarm data from any device on the monitoring system at a single point—the personal computer.
Protocols provide a common convention for power monitoring system components to communicate with each other. Power monitoring system components that use disparate protocols will be unable to effectively exchange information. Monitoring device manufacturers may use proprietary protocols or open-source protocols. There are a multitude of proprietary protocols available; however, Modbus TCP/IP is probably the most popular open-source protocol. Some metering products can communicate using mixed protocol modes, with both proprietary and open-source protocols. (An explanatory white paper is available in PDF form at the Modbus Web site) The advantage of using an open-source protocol is that the software can be configured to read data from monitoring devices made by various manufacturers.
Where Should the Equipment Be Installed?
Facility management's goals for the power monitoring system determine both the type of monitoring device to be installed in a federal facility and its best placement. One philosophy is to install high-end metering devices at the main electrical switchgear and less sophisticated metering devices farther into the electrical system. This approach allows the end user to understand the quality of the energy provided by their utility while also understanding basic electrical characteristics within their facility. Another philosophy is to install metering devices that correspond with their application throughout the facility. Conscientious consumers rely on this more expensive approach to understand both their energy usage and the quality of their energy throughout their facility. Monitoring large loads may allow facility management to identify energy savings opportunities while simultaneously identifying electrical parameters that could damage the load. More monitoring points will provide the end users with a better model of their electrical system.
Because power monitoring systems are permanently installed, they operate on a 24/7 basis. Continuous logging of energy-related data provides information on the operational characteristics of an electrical system. This includes where the energy is being consumed, when the energy is being consumed, how the energy is being consumed, and what loads are consuming the energy. This knowledge can help the end user reduce the energy delivered to, and consumed by, their electrical system.
The quality of energy supplied to a federal facility can adversely affect that facility's operation, leading to loss or degradation of equipment. Many high-end monitoring devices include features that notify the end user of potential power quality problems. Some of these devices can also help identify and locate the source of power quality issues.
Making the Choice
As with any investment, the decision to invest in a power monitoring system should be thought through carefully. Federal facility management needs to consider a number of factors when choosing the components of a power monitoring system. By understanding the primary objective(s), they will be able to design and build an efficient and effective power monitoring system that will pay dividends for years to come.
Square D and PowerLogic are registered trademarks of Schneider Electric.