Power Quality Analysis: The Value Of Circuit Level Sub-Metering
August 30, 2016 — By Jeffrey Kistner, G.S.C., Vice President Sales North America, Circuitmeter
The Value of Circuit Level Sub-Metering in Power Quality Analysis
In this article, we explore the rising importance of power quality analysis and outline where technology has made the greatest advances in circuit-level sub-metering. As this article emphasizes, there are many contributing factors to power quality and a variety of benefits available with new circuit level sub-metering technology.
Power quality has been considered a “utility” problem for more than 100 years. Today, great strides have been made by the power supply authorities to install conditioning equipment in the supply infrastructure to minimize poor power quality. Nevertheless, in order to understand these improvements in power quality, we must first consider their causes.
Transmission and distribution can influence power quality but the utility can manage these variables because it has control over its supply network. On the other hand, the utility cannot manage connected consumer loads. Equipment and demand can change daily, and utilities have no information regarding the behaviour of connected loads. Essentially the utility is at the mercy of its customers and these consumer load demands can “pollute” the power supply. As a result we must all deal with unpredictable power quality issues.
Poor power quality can and does adversely affect operations and equipment efficiency, and it increases energy costs. Why is this aspect of our cost base routinely ignored when it is needed in every aspect of our business? Why do we pollute our energy source? The answer is simple, of course. In general, power quality information is not continuously monitored and, therefore, cannot be managed.
Three analogies to consider
1 For the most part, an average facility has a main utility revenue meter and perhaps a few additional meters packaged in its main switchboards. Typically, many of these meters are stand and read meters and simply provide a measurement of volts and amps: in essence, “dumb meters”. Many facilities invest in building automation systems (BAS) as a way to provide efficiencies in operation. These systems are primarily focused on the mechanical loads in a facility: HVAC, boilers, chillers, ventilation, etc. The essence of the BAS is to provide control for comfort and efficiency by collecting information from field sensors and manage systems based on inputs using predetermined protocols when pre-set conditions are met. Some conditions include air temperature, humidity, airflow, water temperature, etc., that ensure the health and comfort of the occupants. These systems rely on input information to measure and manage the systems for the facility.
2 Most businesses rely on a financial accounting system to inform, measure and manage their business. The accounting systems rely on input regarding financial transactions and corporate inventory, payroll, operational costs, plus a wide variety of variables to measure and manage their business. The output allows the business to understand its current financial health, use historical data for projections, and most importantly, maintain precise information to support sound business decisions.
3 Let’s step out of the box. Your automobile is regulated to give an EPA rating. This rating is based on standards and your experience will depend on your driving habits and conditions. Most of today’s automobiles come with a sophisticated onboard computer which calculates the distance you can travel until you have to refuel and provides varied data on the vehicle’s status and external conditions. With this information, you can adjust your driving habits to maximize efficiencies and reduce mechanical failure. In fact, today’s vehicles provide more information about the status of the vehicle than many facilities have for their energy consumption.
Information is power
What do these analogies have in common? They all refer to technologies that collect, measure and process data, and ultimately help their host manage and improve performance, based on factual information. These examples, use the power of information to improve efficiencies, maximize asset life cycles, and ultimately decrease operating costs.
For far too long, we have accepted energy consumption as the cost of doing business. Why is it not common to manage energy costs using similar management tools? Generally speaking, it it because it widely accepted that the technology is too expensive to implement and that it would take too much work to make it worthwhile. According to the U.S. Department of Energy, the average business spends 33% of its revenue on energy. In general, a facility will manage every other aspect of the business to improve the bottom line yet manage a third of the operational costs on an ad hoc basis. When it comes to power quality, we blame the utility, not realizing the causes are likely ‘behind the meter’.
Every piece of electrical equipment is affected by Power Quality (PQ) within all facilities and should be of major concern to every facility manager and operator. However, in the majority of cases, PQ information is either measured only at the incoming utility supply or not at all. An important oversight about power quality is that poor PQ can be caused by the connected loads within a facility and not solely from the utility supply. Today, sub-metering technology has advanced to provide PQ data down to the circuit level. Affordability, combined with powerful analytic software, enables every facility manager to access the information in understandable terms. By providing user friendly menus, real time and historical data and most importantly, threshold notifications, every facility can have the energy data available to identify PQ tendencies before these anomalies result in expensive equipment replacement. Sub-metering provides performance benchmarking, efficiency status and the consumption rate of all circuits. Advanced submetering technology provides energy analytics at the circuit level for variables such as power factor, voltage (RMS), inductive and apparent power, reactive power real power and a host of other energy characteristics vital to the efficiency of a facility and the protection of its assets.
In today’s world, we take many things for granted. Nothing is truer than with electricity and our expectation that it is always available at the flick of a switch. On a larger scale, every commercial, institutional, residential, hospitality, government and industrial facility relies on the constant supply of electricity from the utility to operate, and more so, to survive. Over the decades, utilities have had to face increased demands that place tremendous stress on their infrastructure. To combat the rising demand, energy conservation programs have been implemented. These programs vary from the traditional lighting and HVAC retrofit programs to larger scale energy modeling. All these initiatives benefit the consumer by lowering the demand on the electrical supply infrastructure. Though the intent of these programs is admirable, more is possible.
Conservation efforts can have repercussions
Let’s use electronic lighting retrofits as an example. In the real world, we must consider the era and the original electrical design of a facility. A case in point: every city has many high-rise multi-tenant commercial facilities as part of the city skyline. Many were designed and constructed some fifty plus years ago when it was prestigious to light up the city skyline. Electricity was plentiful and, most importantly, affordable. It was a time when cities illustrated how prosperous they were by the number of lighted buildings dotting their horizon. If we fast forward to present times, we realize that energy consumption needs to be curtailed. Many solutions seem practical: change fluorescent lighting to LEDs and reduce energy consumption. Such changes, however, can produce an unintentional adverse reaction. Harmonic distortion is one contributing factor to poor power quality that directly affects the internal electrical distribution system. Sub-metering can identify this effect and can enable the implementation of corrective measures before equipment begins to fail.
Many facilities experience a poor power factor and are assessed high penalties from the utility for readings outside the acceptable range. Typically penalties are applied for a power factor below 90% and these somewhat hidden charges could add up to thousands of dollars a month or more, depending on the size of the facility. Property managers and operators generally do not understand the cause, given its complexity, or the factors that contribute to the situation.
As an example, it is now common practice to turn lights off when not in use for most buildings, and is a good practice in general. However, many buildings constructed in previous eras were designed with lighting loads to compensate for the reactive loads (motors). Property managers spent months and untold dollars investigating this problem all the while paying high penalties.
Installation of a circuit level sub-metering system would identify the cause of the poor power factor. As facilities began to turn lighting off, the decrease in power factor would be verified by the sub-metering system in real time. The cost effectiveness of the circuit level metering system was roughly equal to a few months’ power factor penalty charged by the utility.
This is merely one example of how power quality can be impacted by the internal infrastructure of a facility and how it is operated. Today, we have an environment rich in nonlinear loads, such as computers, variable-speed drives, electronic lighting and the introduction of electric vehicle charging (EVC). The operation of these devices represents a double-edged sword. Although they provide greater efficiency, they can also cause serious problems with respect to power quality in distribution systems. Given our attraction to new technology and the benefits that they offer, circuit level metering is likely to be soon regarded as a necessity in the pursuit of efficiency, power quality correction and, most importantly, improving the bottom line.
Technology is progressing at a breakneck pace. We have available ways and means to manage our energy and monitor power quality at a resolution and granularity once reserved for very expensive and specialized testing equipment. An article appearing in Electrical Construction and Maintenance (EC&M) magazine in March 2012 entitled “Power Quality Measurement and Analysis Basics” (by Randy Barnett) emphasized the importance of power quality and analysis. The following excerpts are of particular interest in this context:
“Analyzing electrical parameters associated with distributing electricity is viewed by many as complex engineering work. Yet, for engineers, electricians, and technicians troubleshooting equipment problems these days and for contractors maintaining electrical systems measuring power quality is becoming as much of a necessity as using the clamp ammeter to find out why the overloaded circuits keep tripping.”
When any electrical system fails to meet its purpose, it is time to investigate the problem, find the cause, and initiate corrective action. The purpose of the electrical distribution system is to support proper operation of the loads. When a load does not operate properly, the quality of the electric power in the system should be suspected as one possible cause.”
The piece goes on to describe the process of good planning, processes and determining a baseline. The process could take weeks or months to accumulate data and analyze collected data. It was noted that the process was tedious and to be as accurate as possible each of the tests would be meticulously noted for future analysis. The process for the PQ audit was very well explained making references to the testing manufacturer’s supplied software and using IEEE Power Quality Standards and NFPA 70B, both excellent resources to help understand power quality terminology, issues, and corrective actions. Fee-based services for power quality audits and analysis have been offered by professionals to help businesses understand the issues they are experiencing. These audits could be a one time experience if the issues are captured at the time of the audit or may have to be repeated to find the cause(s).
Fast forward a few years where new submetering technology is now available that allows for granular measurement of energy use, right down to the individual circuit level, at dramatically lower costs than previous generations of “hardware – centric” technology. With real time, circuit level submetering, a completely new level of insight into energy performance can be generated. Equipment that is operating with a low power factor, or with a higher energy consumption than benchmarked, can be identified and flagged for maintenance or replacement.
This overall analytical capability is sometimes referred to as “continuous energy audit”. Advanced submetering companies, such as Toronto based CircuitMeter Inc., provide continuous circuit level metering collection of granular electrical data in real time at a fraction of the cost of industry standard revenue-only sub-meters. Considering the above described process for a power quality audit, the value proposition of circuit level metering offers great advantages to the end user. The ability to continuously monitor every circuit in real time establishes, amongst other benefits, a power quality baseline. The advantages of this benefit are very clear: if power quality parameters change, the advanced energy monitoring system will report and notify the end user of the changes. The cause of the change can be identified immediately and corrective actions can be implemented. Further to this, the historical data is available to pinpoint exact causes of power quality decline. With user friendly point and click analytics with common terminology, end users can perform analytics confidently and seek the appropriate help for corrective measures.
One heavy industrial facility visited was having a multitude of power quality problems, in particular, power factor issues. The utility had told the business to take corrective action as they were also causing power quality problems downstream. The penalties levied every month were excessive compared to the kWh charges. In their efforts to implement corrective measures, they contracted an energy auditor to analyze power quality within their facility. Due to the size and complexity of the facility, the audit took some time to complete. The audit report recommended installing numerous variable speed drives and capacitors to compensate for the low power factor. All these recommendations appeared to be sound advice based on information gathered in the audit and logical reasoning.
During the audit period, the company began installing a circuit level sub-metering system for maintenance purposes. The system recorded the energy signatures for performance, run time and operation cycle. With these benchmarks, the system detected variances on every piece of equipment and notified maintenance before a failure had occurred. Using the system analytics, the contributing factors which were responsible for the poor power factor condition were easily identified. Sharing this information with the auditors, the business put in place changes to their operating procedures and began to manage their manufacturing more effectively, thereby reducing the need to purchase the amount of corrective equipment as originally proposed. The capital cost savings more than paid for the implementation of the circuit level metering. Once the cost savings associated with the reduction of downtime, planned and unplanned, through precision maintenance were accounted for, the result was a very respectable ROI with a payback of less than one year.
Energy accounting and analytics are essential tools for business and facilities. Circuit level metering has come a long way since the first electronic meters were introduced. Modern IP-based submetering systems can help turn facilities into Intelligent Buildings. The information gap is bridged by easily connecting with building automation systems and IT-based financial and energy management systems, and making energy data visible to all facility owners and operators. Facility managers have the tools available to not only manage their energy consumption but also their energy quality and ultimately save money.
A system capable of providing real-time intelligent information to the end user to measure and manage its energy is one simple step forward. A system providing intelligent real-time energy information including power quality to the utility is a giant step forward in power quality of electricity delivery and stability. By using these systems, a Smart Grid can become a live Intelligent Grid.
Jeffrey Kistner, G.S.C., is VP of Business Development at CircuitMeter Inc., with over 40 years’ experience in the electrical and telecommunications industries. CircuitMeter Inc., a privately held Canadian firm, has developed groundbreaking electrical energy submetering hardware, integrated with Big Data and cloud based CircuitMonitoring™ enterprise software. The advanced energy analytics represents a major step forward in comparison with current practice and is designed to analyze real time, circuit level energy usage for large organizations and portfolio managers.