The Basics of Power Monitoring Systems

Dec 1, 2007 12:00 PM, By Jon A. Bickel, Square D Co./Schneider Electric

What you need to know when evaluating the need for a power monitoring system or reassessing an existing one

Rationalizing an investment in a facility's infrastructure can be a difficult prospect for any plant engineer or technician, often requiring extensive justification. Investments that are deemed “low-risk” by upper management and have a fast return on investment (ROI) are typically the easiest to substantiate. One such investment that will pay considerable dividends over the course of its operating life is a comprehensive power monitoring system.

Because power monitoring systems operate around the clock, they can provide comprehensive historical data that helps end-users reduce the energy delivered to and consumed by electrical systems in their facilities.

Even though increased energy prices have become a larger influence on the balance sheet, many facilities do not take advantage of opportunities to better manage these expenses. Those without power monitoring systems likely have no understanding of their energy usage; those with them may not be using their systems to the fullest potential. In order to optimize a power monitoring investment, it's important to understand both the intended application and energy usage priorities within the facility.

When evaluating the need for a power monitoring system — or reassessing an existing system — it's important to ask yourself certain questions.

Who needs a power monitoring system?

A properly installed and configured monitoring system is a valuable asset to almost any type of energy consumer. Energy consumers have a wide variety of considerations and concerns where energy usage is involved. This is largely due to the diversity of load types and requirements, energy consumption schedules, and the facility's level of toleration for a less-than-ideal energy source. In general, there are four basic categories of consumers: industrial, commercial, governmental, and residential. While each has a different objective for energy consumption and different expectations from its energy provider, many commonalities exist.

Energy usage/cost and the reliability of the electrical system are major concerns for most energy consumers. Different rate structures exist, depending on the category of consumer. Basic residential consumers generally incur a flat or tiered billing structure rate that corresponds to their energy usage. More complex loads, such as industrial and commercial consumers, incur more complex rate structures that typically include some variation of power demand and energy usage. Clearly, power monitoring systems become more beneficial for heavier consumers.

Monitoring systems are also very useful for consumers that have a low tolerance for electrical perturbations, such as semiconductor fabrication or pharmaceutical industries. In these cases, the consumer's need for a reliable power source may outweigh their energy cost considerations because of the expenses associated with equipment downtime (e.g., loss of product, equipment, etc.). For this category of consumer, monitoring systems are used to quickly identify and resolve problems occurring on 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 you reduce the energy delivered to and consumed by your electrical system.

Because the quality of energy supplied to a facility can adversely affect its operation, oftentimes leading to loss or degradation of equipment, product, revenue, and reputation, plant managers must weigh the advantages of implementing a power monitoring program.

Why install a power monitoring system?

There are many benefits to installing a power monitoring system — some of which strongly interrelate with each other. A properly designed and installed monitoring system offers a deeper understanding of the operational parameters of the facility's electrical system. A close appraisal of the data generated by a monitoring system can reveal a variety of overt and subtle opportunities, including:

Environmental — A better knowledge of how energy is used within a facility allows you to identify an array of prospects to improve efficiency, minimize waste, and reduce energy consumption, thereby allowing the facility to be a better steward of its allotted natural resources.
Reliability — Assessment of data from the monitoring system can reveal existing or imminent issues that can adversely affect the operation and product within a facility. Historical data from power monitoring systems can help locate and correct both acute and chronic problems, resulting in increased productivity.
Maintenance — Data trends can forecast and notify the appropriate people when discrete equipment parameters may be exceeded, allowing you to plan ahead instead of facing an unscheduled shutdown.
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. Some monitoring devices also offer a variety of additional parameters (temperature, pressure, flow rate, vibration, status indicators, etc.) through the use of transducers.
Financial — Each benefit discussed above either directly or indirectly influences a business's bottom line. In most cases, the monetary impact from even one or two benefits can quickly justify the purchase and installation of a power monitoring system.

Additional advantages offered by power monitoring systems may include features such as accurate evaluations of spare electrical system capacity, billing allocation and validation, or optimum placement of mitigation devices. Once you decide if a power monitoring system makes sense in your particular situation, the next step is narrowing the field of choices.