No matter the facility, unplanned downtime can be extremely costly. In this post we’ll look at some of the impacts of downtime, the parts that power availability and reliability play in this equation, and the five ways that digital products, software, and services working together can help.
The real cost of downtime depends largely on the type of organization. For example, a Ponemon study reported that the average cost of a data center outage is over $740k. In healthcare, the average estimated downtime cost per minute is $8,662, an outage lasting 8 hours could cost $4.1M and this doesn’t even include the critical risks to human life. U.S. commercial and industrial businesses reported that 40% had experienced a power outage costing more than $50,000 during the last year, with 2% reporting losses over $2 million.
So what’s the cause of these outages? Some are the result of major power grid outages. In fact, extreme weather events have been increasing in recent years, with sixteen weather disasters with losses in the billions of dollars experienced in the U.S. in . Another major contributor is a facility’s own internal power infrastructure. Electrical networks are becoming more complex, with decentralized power sources and more power electronic devices causing more power quality ‘pollution’. These conditions can impact the reliability of increasing amounts of digitized, power-sensitive equipment. If power distribution is not designed, protected, monitored, and maintained properly, there can be hidden risks to the power availability you depend on.
Let us clarify a couple of definitions that are often confused. Understanding these terms can help us better understand best steps forward.
The power availability and reliability of a distribution system encompasses its entire lifecycle, from design to operations. Consider these five approaches:
A pre-engineered medium and/or low voltage electrical distribution system will be based on a reference design that has been validated for the specific application.
A design should include the core power system design, as well as the connected, digital layer of intelligence used for power management. To further enhance resilience the design can include backup power and power conditioning (e.g. generators, uninterruptible power supplies (UPS), automatic transfer switches (ATS), harmonic filtering). It should also comply with local regulations and international standards, and be optimized for safety to help avoid injury to people and damage to equipment.
A pre-engineered reference design will also significantly streamline the design-build process, reducing both the overall risk and cost of implementing and operating the system. Specialized electrical distribution design software optimizes every aspect of the system for its specified application, taking into account all expected operational and environmental conditions, today and tomorrow. This will help future-proof the facility.
The newest circuit breaker technology protects people and equipment, while at the same time maintaining the operations of a facility. If a fault occurs at any point in an electrical distribution circuit, you don’t want that fault to affect the power availability for the entire facility. Selective coordination is used by circuit breakers to rapidly isolate the problem section, tripping only the circuit breaker directly upstream of the problem section, without depriving the rest of the network of power.
Electrical distribution design enables you to optimize your installation design, selecting sizes and combinations of circuit breakers to provide ‘total’ selective coordination between all stages of the electrical distribution network.
The best circuit breakers are easy to maintain, withdrawable and plug-in features makes them easier to manage. Smart circuit breakers also offer embedded metering capabilities to support connected power management and predictive maintenance.
Throughout your power distribution system, there can be risks to reliability that are hidden and go unnoticed. A fully digitized electrical system can better withstand power disturbances and is resilient to downtime. A power management system takes advantage of data from connected devices, acting like a microscope on your electrical system, continuously monitoring its performance and the assets connected to it. If any unexpected condition is detected, an alarm notifies personnel wherever they are so that they can immediately locate the issue and take action to prevent a critical situation.
A connected power network includes intelligent, connected advanced power meters that quickly reveal power quality issues – such as high harmonics or voltage sags – or other types of faults, while diagnostic tools help facility team determine root causes before they can cause an outage.
A digitally-connected power management solution should also include wireless thermal sensors, for early detection of abnormal temperature rises on conductors and connection points. This will help reduce the risk of a fire or failure (and associated downtime), while avoiding the time and cost of annual infrared (IR) testing. Another recent innovation is the ability to monitor circuit breaker health and aging, with advanced analytics that enable more proactive maintenance, preventing performance issues, and extending breaker life. These capabilities help ensure that a clean, stable power is always available 24/7, while reducing operational costs.
Cloud-based power management applications act as a portal to remote expert services. If your organization has limited onsite technical resources or expertise, these ‘digital services’ can help you reduce the complexity and time needed to manage your power distribution systems, while improving power quality, reliability, and availability.
Expert advisors will monitor your operation 24/7, delivering condition-based insights about your electrical system health and asset performance. These insights enable a more predictive maintenance approach, resulting in fewer operational failures and a downtime reduction of 30 to 50%. Advisory services, including Schneider Electric EcoXpert partners, can also help you evolve your system over its life cycle.
Despite taking all these steps to prevent downtime, there is always the chance of unplanned downtime. If a fault occurs, you need to minimize its duration and impact. Having the right products and software will help ensure a rapid recovery. Some of the newest tools will the on-site facility team automatically correlate system-wide data and reveal the propagation of a disturbance to isolate the source. In addition, smart protection relays, trip units, and accessories (e.g. auxiliary contacts, etc.) will help more quickly localize a fault, identifying the tripped circuit-breaker and its associated circuit. A smartphone app can then be used find the root cause of the incident, and have access to step-by-step guidance to help quickly restore power.
In the more complex, more power-sensitive ‘New Electric World’, businesses face the risk of more unplanned downtime, highly inefficient electrical operations, and more frequent equipment failures. These can all lead to higher OPEX spending and, in some cases, major financial losses. For these reasons, more focus must now be placed on using the right technologies and services to help ensure innovative power solutions.
Electric power quality is the degree to which the voltage, frequency, and waveform of a power supply system conform to established specifications. Good power quality can be defined as a steady supply voltage that stays within the prescribed range, steady AC frequency close to the rated value, and smooth voltage curve waveform (which resembles a sine wave). In general, it is useful to consider power quality as the compatibility between what comes out of an electric outlet and the load that is plugged into it.[1] The term is used to describe electric power that drives an electrical load and the load's ability to function properly. Without the proper power, an electrical device (or load) may malfunction, fail prematurely or not operate at all. There are many ways in which electric power can be of poor quality, and many more causes of such poor quality power.
The electric power industry comprises electricity generation (AC power), electric power transmission and ultimately electric power distribution to an electricity meter located at the premises of the end user of the electric power. The electricity then moves through the wiring system of the end user until it reaches the load. The complexity of the system to move electric energy from the point of production to the point of consumption combined with variations in weather, generation, demand and other factors provide many opportunities for the quality of supply to be compromised.
While "power quality" is a convenient term for many, it is the quality of the voltage—rather than power or electric current—that is actually described by the term. Power is simply the flow of energy, and the current demanded by a load is largely uncontrollable.
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The quality of electrical power may be described as a set of values of parameters, such as:
It is often useful to think of power quality as a compatibility problem: is the equipment connected to the grid compatible with the events on the grid, and is the power delivered by the grid, including the events, compatible with the equipment that is connected? Compatibility problems always have at least two solutions: in this case, either clean up the power, or make the equipment more resilient.
The tolerance of data-processing equipment to voltage variations is often characterized by the CBEMA curve, which give the duration and magnitude of voltage variations that can be tolerated.[3]
Ideally, AC voltage is supplied by a utility as sinusoidal having an amplitude and frequency given by national standards (in the case of mains) or system specifications (in the case of a power feed not directly attached to the mains) with an impedance of zero ohms at all frequencies.
No real-life power source is ideal and generally can deviate in at least the following ways:
Each of these power quality problems has a different cause. Some problems are a result of the shared infrastructure. For example, a fault on the network may cause a dip that will affect some customers; the higher the level of the fault, the greater the number affected. A problem on one customer’s site may cause a transient that affects all other customers on the same subsystem. Problems, such as harmonics, arise within the customer’s own installation and may propagate onto the network and affect other customers. Harmonic problems can be dealt with by a combination of good design practice and well proven reduction equipment.
Power conditioning is modifying the power to improve its quality.
An uninterruptible power supply (UPS) can be used to switch off of mains power if there is a transient (temporary) condition on the line. However, cheaper UPS units create poor-quality power themselves, akin to imposing a higher-frequency and lower-amplitude square wave atop the sine wave. High-quality UPS units utilize a double conversion topology which breaks down incoming AC power into DC, charges the batteries, then remanufactures an AC sine wave. This remanufactured sine wave is of higher quality than the original AC power feed.[5]
A dynamic voltage regulator (DVR) and static synchronous series compensator (SSSC) are utilized for series voltage-sag compensation.
A surge protector or simple capacitor or varistor can protect against most overvoltage conditions, while a lightning arrester protects against severe spikes.
Electronic filters can remove harmonics.
Modern systems use sensors called phasor measurement units (PMU) distributed throughout their network to monitor power quality and in some cases respond automatically to them. Using such smart grids features of rapid sensing and automated self healing of anomalies in the network promises to bring higher quality power and less downtime while simultaneously supporting power from intermittent power sources and distributed generation, which would if unchecked degrade power quality.
A power quality compression algorithm is an algorithm used in the analysis of power quality. To provide high quality electric power service, it is essential to monitor the quality of the electric signals also termed as power quality (PQ) at different locations along an electrical power network. Electrical utilities carefully monitor waveforms and currents at various network locations constantly, to understand what lead up to any unforeseen events such as a power outage and blackouts. This is particularly critical at sites where the environment and public safety are at risk (institutions such as hospitals, sewage treatment plants, mines, etc.).
Engineers use many kinds of meters,[6] that read and display electrical power waveforms and calculate parameters of the waveforms. They measure, for example:
In order to sufficiently monitor unforeseen events, Ribeiro et al.[7] explains that it is not enough to display these parameters, but to also capture voltage waveform data at all times. This is impracticable due to the large amount of data involved, causing what is known the “bottle effect”. For instance, at a sampling rate of 32 samples per cycle, 1,920 samples are collected per second. For three-phase meters that measure both voltage and current waveforms, the data is 6–8 times as much. More practical solutions developed in recent years store data only when an event occurs (for example, when high levels of power system harmonics are detected) or alternatively to store the RMS value of the electrical signals.[8] This data, however, is not always sufficient to determine the exact nature of problems.
Nisenblat et al.[9] proposes the idea of power quality compression algorithm (similar to lossy compression methods) that enables meters to continuously store the waveform of one or more power signals, regardless whether or not an event of interest was identified. This algorithm referred to as PQZip empowers a processor with a memory that is sufficient to store the waveform, under normal power conditions, over a long period of time, of at least a month, two months or even a year. The compression is performed in real time, as the signals are acquired; it calculates a compression decision before all the compressed data is received. For instance should one parameter remain constant, and various others fluctuate, the compression decision retains only what is relevant from the constant data, and retains all the fluctuation data. It then decomposes the waveform of the power signal of numerous components, over various periods of the waveform. It concludes the process by compressing the values of at least some of these components over different periods, separately. This real time compression algorithm, performed independent of the sampling, prevents data gaps and has a typical :1 compression ratio.
A typical function of a power analyzer is generation of data archive aggregated over given interval. Most typically 10 minute or 1 minute interval is used as specified by the IEC/IEEE PQ standards. A significant archive sizes are created during an operation of such instrument. As Kraus et al.[10] have demonstrated the compression ratio on such archives using Lempel–Ziv–Markov chain algorithm, bzip or other similar lossless compression algorithms can be significant. By using prediction and modeling on the stored time series in the actual power quality archive the efficiency of post processing compression is usually further improved. This combination of simplistic techniques implies savings in both data storage and data acquisition processes.
The quality of electricity supplied is set forth in international standards and their local derivatives, adopted by different countries:
EN is the European standard for power quality, setting the acceptable limits of distortion for the different parameters defining voltage in AC power.
IEEE-519 is the North American guideline for power systems. It is defined as "recommended practice"[11] and, unlike EN, this guideline refers to current distortion as well as voltage.
IEC -4-30 is the standard defining methods for monitoring power quality. Edition 3 () includes current measurements, unlike earlier editions which related to voltage measurement alone.
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