The Path to Protection

Paul Haake details the most common power problems faced by industrial facilities and describes the solutions that help to ensure uninterrupted operations.

Today’s engineers are designing more and more sophisticated control systems that bring higher productivity to meet ever increasing expectations of performance – all while keeping system costs under control. In order to achieve these results, they are employing more electronic equipment, much of it adopted from non-industrial applications, and almost all of it more sensitive to electrical disturbances than the equipment being replaced.

These new realities are then mixed with the inherently poor power environment of an industrial facility and aging power generation and distribution facilities – both inside and outside of the plant to produce a wide variety of power and electrical noise problems.

Understanding these problems, along with some of their causes and solutions, can help ensure the design of mission critical electronic systems that are both reliable and cost-effective.

Mission-critical elements

The first task in protecting mission critical elements is to identify them. While each system is unique, the mission critical components are usually easily recognized. They include items that, if they fail, will cause customer displeasure, increased labor, or increased material cost.

Typically, programmable logic controllers (PLCs), industrial computers, and electronic motor speed controls serving in the control loop of a manufacturing process are the first components that are put on the “mission critical” list. But, this list is far from complete.

Sensors, data communication equipment, actuators, and even production planning systems must be included to achieve a high level of customer satisfaction and minimize costs due to downtime. As each component is evaluated for inclusion on the critical component list, remember it’s “mission critical” if its downtime causes lost profits.

Once this list of mission critical components and systems is identified, the next step is to determine the necessary level of protection. When making this decision, it is valuable to look at achieving three distinct levels of protection.

The first level of protection provides a defense against the instantaneous destruction of critical equipment. This is often the level of protection desired for a home computer or entertainment center – just enough protection to keep things from catastrophically failing. The second level provides additional protection against long-term degradation of equipment, a condition often seen in semiconductor devices.

And the third level, which is the most important for most industrial systems, adds defense against disruption – those unexplained soft failures, system lockups and resets for which no specific cause can be identified. As more devices containing volatile memory find their way onto the production floor, guarding against such disruptive events becomes even more critical to ensure that these costly interruptions do not occur.

If satisfied customers and controlled costs are of primary importance, there is little question that systems must be protected to this third and highest level. To accomplish this, it is critical to use a “total protection solution” for the identified mission critical systems. This approach requires that each and every input and output line, whether power or data, be examined and appropriately protected against likely hazards.

Achievement of this level of protection usually requires the use of industrial grade components, along with a combination of devices such as surge protectors, power conditioners, power conditioned uninterruptible power supplies (UPS), as well as appropriate grounding techniques.

Power line issues

Power line problems that can cause the destruction, degradation, or disruption of mission critical equipment can originate either “inside” or “outside” the industrial facility.

Outside problems include inclement weather that produces lightning-induced transients or power line outages due to high winds or ice. Power problems may also come from routine utility operations such as capacitor switching to effect power factor correction, or from the clearing of line faults.

While outside events are the most obvious and spectacular, it is estimated that in industrial facilities, up to 80 percent of power related problems originate on the customer’s side of the meter. Inside problems are caused by a wide variety of factors, including stopping and starting of motors, welding equipment, electronic motor speed controls, poor grounding, and some of the same problems facing the utility company—fault clearing, and capacitor switching.

The results of these events show themselves in ways such as voltage interruptions, sags, and the less obvious – but more disruptive – voltage transients.

Power interruption

Among the most noticeable power quality problems is a power interruption. While power interruptions are relatively infrequent in most locations, their effect can be dramatic and obvious, as everything grinds to a halt.

Solutions to combat power interruptions include alternate power feeds to the facility, local back-up generating capability (diesel or gas powered generators) and the addition of UPSs on selected equipment. While alternate power feeds and local power generation may not be practical for every facility, the addition of UPSs, particularly to software controlled devices, is an important component in a total protection strategy.

When properly selected, the UPS will ensure that the attached devices are kept active during an outage. With proper communications interface software, these devices can also smoothly and automatically shut down all running software applications and the operating system, to ensure a clean restart of the process – a factor particularly important in batch processing applications.

Voltage sags

Voltage sags, and to a lesser extent voltage swells, are reported to be the most measured power line problem. A study of one site estimated that up to 62 voltage sags down to a limit of 80 percent of nominal voltage, and an additional 17 sags down to a limit of 50 percent of nominal voltage occurred yearly at that site.

In another study of a large industrial facility, more than 500 sags of various levels were recorded at the input to key control equipment over a 3.5 month period. In the same study, only about 100 such sags were recorded during that period on the input power line to the facility. Both of these studies also report that individual pieces of control equipment were affected quite differently by the recorded voltage sags.

As with power interruption, solutions can be applied both locally and plant wide. Plant wide solutions include layout of power distribution to minimize the number of sags induced on critical equipment from internal causes such as starting motors and fault clearing. Since studies show that up to 80 percent of sags are caused within the plant, such solutions, while expensive, can greatly aid in protecting critical control components from unwanted sags.

Typically, however, a more practical approach for protecting controllers is the application of a voltage control device in the power path supplying the control system. Because these local devices can compensate for sags generated both inside and outside of the facility, using them is usually more reliable and less expensive than attempting a plantwide solution.

At least three basic types of devices that provide local sag protection are available. These include devices that store energy in a transformer (constant voltage transformer); devices that use boost windings to raise voltages during sags (tap switching transformer); and devices that supply energy from batteries during sags (uninterruptible power supplies). There are also devices that use some combination of these three technologies to combat sags.

While each of these solutions has its advantages and disadvantages, some are better suited than others to today’s electronic control systems. In the past, the most common device applied to control sags was the constant voltage transformer (CVT). This device, which also typically provided the step down voltage function, was an excellent choice when most control devices used linear power supplies, most sags were not too severe, the attached control system “crashed” well, and the CVT was presented with a relatively constant load.

Today, however, control systems have changed. Loads are more typically switch mode power supplies (SMPS), and sags – particularly with deregulation – are likely to become more severe. In addition, control systems are often no longer based on proprietary software that “crashes” well, but on commercially available operating systems that need to be properly shut down in order to start up smoothly. Power system load requirements also change more often as control schemes are frequently updated with the latest technology in order to gain additional performance from existing tooling and equipment.

While changes have been made in many CVTs to adapt to this new technology, the best solution is one that was specifically designed to support SMPS and has more energy to ride through severe sags than a typical CVT. Such a device is a USP with integral isolation transformer that provides highly robust regulation, isolation, and backup. If an isolation transformer already exists in the power path near the load, a UPS with double conversion topology can also serve quite effectively.

Transient voltages

By their very nature, transient voltages on power lines, below the level of those that cause massive destruction, are difficult to measure directly. Among the most difficult to measure are the high-speed transients that are the most likely to cause disruption of electronic equipment.

To further complicate the situation, transients often occur randomly; and special power quality monitoring equipment is usually required to capture the high-speed impulse and oscillatory events that can cause sensitive electronic equipment to be disrupted. While often not discussed or considered, this “least measured” power quality event can be a major contributor to those random errors and “lockups” that occur in a control system.

As with many industrial power quality issues, most of the high speed transients that cause system disruptions are not supplied through the power utility, but are generated inside, i.e. within the facility. This conclusion can be reached not only by observation, but through examination of the typical transient’s high frequency content and its interaction with the intrinsic impedance of power distribution lines.

The one obvious exception is lightning, which is clearly a natural and external event. Typical inside causes of transient events include switching devices such as contactors, motor starters, compressors, variable speed drives, and the switching of capacitor banks for power factor correction.

It is important to note that while these transients are clearly a threat to a mission critical system’s overall reliability, not every transient will cause a system disruption. The transient’s frequency, edge speed, the mode in which it appears to the equipment, and where it occurs in the affected equipments’ clock or processing cycle will all determine its immediate impact.

Clearly, almost all transient events are ignored by electronic equipment. If they were not, it would be almost impossible to keep a computer running. However, in mission critical applications the goal is to push disruptions as close to zero as is possible, and the reduction or elimination of these transients is critical in achieving this result. Specifically, reducing the amplitude and edge speed of all transients becomes paramount in achieving the desired system reliability.

Transients are said to be “normal mode” (NM) noise when they appear between the line (hot or phase) and neutral conductors supplying the equipment. While somewhat troublesome, noise appearing in this mode can often be controlled by a combination of transient voltage surge suppressor (TVSS) devices and filters.Typically, individual pieces of equipment often make some provision for controlling this noise mode within the control equipment itself.

The far more difficult noise mode to control is “common mode” (CM). In this situation, there is noise between the neutral line and the ground line connected to the equipment. While the neutral and common are bonded either at the service entrance or at an intermediate transformer, noise in this mode is quite common, and very disruptive.

Common mode noise typically occurs when current is “dumped” into the ground lead by other equipment; input and output filters to suppress high frequency line noise are a typical cause, as are protective devices such as TVSSs.

Control of common mode noise usually requires a transformer based power conditioning device that provides a “separately derived” source of power in which the neutral and ground wire are locally rebonded.

Almost all such commercial power conditioning devices also include appropriate components to control any normal mode noise that is present. These devices, which are typically available as traditional power conditioners or as power conditioners with battery backup, accomplish the necessary reduction in amplitude and edge speed of transient noise sources to help ensure that equipment in mission critical systems is not unnecessarily effected by transient events.

In addition to installing an appropriate power conditioning device, proper care must be taken in system layout and wiring. In particular, it is critical that the wiring to the power conditioner not be run with the power from the output of the power conditioner. Running these wires in the same conduit or wiring tray will significantly reduce the benefits provided by installing the power conditioner.

It is also important that, whenever possible, all critical devices, including sensors, be powered from the same power conditioner as the controller, and that sensor and peripheral equipment grounds be connected at a common point. Finally, data communication cables should be run in conduit or wiring trays that do not contain power, or at a minimum, do not contain unconditioned power.

Communication line issues

Today’s typical control system makes use of a variety of communication lines, such as control buses like DeviceNet, or Profibus, data networks to peripheral devices such as human machine interfaces (HMIs), and connections to plantwide production information systems.

While not subject to all of the problems of power lines, communication lines are often more likely to cause system disruption due to transients. In addition, grounded (non-isolated) communication schemes such as RS232 and RS485, provide an opportunity for an additional path of disruption known as ground skew.

Line protectors

As in power lines, a user must be concerned about destruction, degradation, and disruption when addressing communication line protection. In communication lines, minimizing the chance of destruction or degradation is best addressed by the use of a communication line protector (CLP).

Typically, the semiconductor devices associated with communication lines are not designed to withstand the high voltages or currents that can be induced from power lines or other noise sources, and thus need to be protected with a CLP.

Selection of CLPs should be done with care to ensure that the clamping voltage is lower than the point at which damage will occur, but higher than the maximum voltage that can be applied to the line for normal communication. In addition, when using systems with the higher transmission speeds now available, care must be taken to ensure that the insertion loss due to the added capacitance and inductance of the CLP will not cause unacceptable signal level reductions.

Use of external CLPs is often suggested to improve system reliability, even if a communication port is internally protected by a TVSS against over voltage. This approach can lead to improved reliability since a typical CLP will have a grounding lead which can be wired to direct transient noise away from the chassis ground of the control device. Redirecting this transient noise current will avoid introducing potentially disruptive common mode noise into the equipment, a situation that can occur if the internal TVSS is triggered.

For this scheme to have value, however, the external CLP will be required to activate at a lower voltage level than the internal protective devices. While proper selection of an external CLP will provide this result, the selection requires investigation into the internal protection levels for each piece of equipment in order to ensure proper coordination.

Good grounding

While CLPs can provide protection against system destruction and degradation, they do little to assist in reducing disruptions from transient voltages that are below the level of component destruction, but above the disruptive level that interferes with routine communication. Protection against such disruption can be addressed in several ways.

First, it is critical that system grounding follows good practice, and meets the equipment manufacturer’s guidelines. With grounded communication schemes in particular, a small grounding problem can lead to very inconsistent communication.

A second key factor is cable routing, which should be done in a manner to avoid inducing any noise into communication cables from other sources. In particular, to maximize system reliability, do not run communication cables with power cables, and when crossing power cables, if at all possible, do so at right angles.

Addressing ground skew is the next step in improving communication reliability. Ground skew problems occur when noise currents flow in a ground path between two pieces of equipment connected by more than one ground lead.

In grounded communication systems, the primary connection is the power ground, while the second ground lead is the shield and or common lead in the communication cable. When ground currents flow in the power ground, they cause a voltage difference (ground voltage skew) between the two locations, thus causing a voltage differential to be reflected in the communication cable. This voltage differential and the resultant current flow in the communication cable can cause serious disruption of the communication path, and can even destroy devices not protected by a CLP.

There are two solutions to eliminate or reduce ground skew related problems. The first, most expensive, and often most difficult to implement is full isolation on the communication port. Such isolation typically requires separate power supplies be added at each end of the line, in addition to adding the appropriate isolation device. While commercially available, such devices are relatively expensive and take time to install. To avoid such costs, an alternative solution is desirable.

One alternative solution to ground skew induced problems is a ground skew protective device in the power path. Such a device is available from multiple sources, each with slightly different, and patented, implementations. The device works on the principle of creating a high impedance in the ground path at high frequencies while maintaining a “zero” (Chloride implementation) or low (other implementations) impedance at power line frequencies.

By increasing the high frequency impedance in the ground line, the resultant voltage produced by high frequency ground currents is substantially reduced, thereby reducing the opportunity for disruption or destruction of the communication line.

In order to ensure proper protection, one ground skew device should be placed in the power path of each device containing a grounded communication port. Commercially, ground skew devices are typically sold as an internal option to power conditioners and power conditioned UPSs.

Towards total protection

In order to provide the highest level of confidence in the reliability of a mission critical industrial system two steps are required. First, robust equipment designed to be used in an industrial environment must be selected. While this article discusses techniques to minimize the effect of electrical anomalies on the system, items such as working temperature range and mechanical ruggedness are also important to ensure long-term system reliability.

Once the proper equipment is selected, installing it with the proper total protection solution on power and communication ports becomes of paramount importance to provide a system that is as failure free as possible.

When installing equipment with the goal of achieving a total protection, it is important to protect each and every power and communication port into the system and provide a grounding scheme that is in accordance with regulatory and manufacturers’ guidelines.

In a well protected system, each power port should be protected with a low impedance transformer based power conditioner to control both common and normal mode noise. On some power ports a low impedance transformer based power conditioner with batteries (UPS) may be the proper choice to provide protection against extended sags and outages when sensitive controllers need to be shut down in an orderly fashion.

In addition, each communication line should have a CLP installed that has the appropriate voltage breakdown level and controlled insertion loss for the type of communication port being protected. When grounded communication lines are involved, either ground skew protection devices, or full isolation of the ports should be considered.

Finally, remember that once a system is properly installed and protected, vigilance is required to maintain the level of integrity that was originally designed in. One single “on the fly” addition or change can leave a system with an unprotected path, and subject to the disruptive effects of power and communication line anomalies.

Paul Haake is Vice President of Engineering for Chloride North Americ.

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Outlook for Asia Pacific UPS Market

A recent (September 2009) report from Frost & Sullivan (www.frost.com), Asia Pacific Commercial Uninterruptible Power Supply Market, reveals that the UPS market in the region is set to reach US$2.12 billion by 2015. This compares to revenue of $1.6 billion that was recorded in 2008.

According to Frost & Sullivan, the outlook for the medium and long term looks encouraging with areas such as the energy sector waiting to be tapped. Infrastructure development and expanding population have unleashed an ever-increasing demand for power, making the introduction of power grids highly necessary.

“The constant concern over reliability and lack of power quality has always been driving the Asia Pacific commercial UPS market,” says Frost & Sullivan research analyst Teoh Chew Yew. “As IT managers are aware of and emphasize virtualization, there is a growing adoption of such technology.”

The market is fiercely competitive, particularly in East Asia. Numerous participants are in the fray and considering the innumerable options to choose from, end users have become highly price sensitive and discerning. An influx of products from China and Taiwan has exerted pricing pressure on products and services, constraining the profit margins, particularly in the small UPS segment.

Thus, innovation and continuous product development are critical to success in the commercial UPS market. As electronic devices become increasingly complex, power quality assumes greater significance and UPS market participants are striving to get the cutting edge.

For instance, to obtain smaller footprint, product development engineers are under pressure to design compact UPS models with minimal R&D budget and manufacturing cost. For online UPS, manufacturers and clients must collaborate to deliver customized solutions or products for niche applications.

“Going forward, the green approach is a surefire route to advance business growth in the commercial UPS market,” adds Teoh. “Participants must go the extra mile to educate and create awareness in the market as this will serve to create a more receptive response for the highly efficient ‘green’ products in the commercial UPS market.”

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Keeping Customers Switched On

From UPS provider Chloride, Tim Cobbold, chief executive, and Etienne Guerou, vice president, South East Asia, tell CE Asia all about the business of supporting critical systems.

Established over 100 years ago, Chloride became one of the 20th century’s most recognizable battery brands. After acquiring its first power protection business in the 1970s and exiting a number of businesses, including emergency lighting, security, as well as batteries, in the 1990s, Chloride’s business switched to focus solely on providing secure power solutions for commercial and industrial facilities. Chloride has a global presence and is actively expanding in Asia where it currently has direct operations in eight key countries. For financial year 2009, recorded revenue was £327 million (US$492 million).

Q: Is it an issue that people still associate Chloride with batteries rather than power protection systems?

A: When Chloride sold off the batteries, the trademark as well as the name were also sold. And so there is, for instance, a Singapore-based company using the Chloride name for the forklift, industrial and automotive batteries that it manufactures. Ideally, we would prefer to have sole use of the Chloride name, but on the other hand, the Chloride brand is very well known and the first thing people look for is recognition. So in a way it does help us, as we can start a conversation by saying, we don’t do batteries anymore. But although we don’t make them, we still supply batteries because of course they are an intrinsic part of a UPS (uninterruptible power supply).

Q: Where does Chloride rank as a supplier in the power protection market?

A: Globally, we are fourth in terms of market share. Schneider Electric (through its APC and MGE brands) is the leader, followed by Emerson Network Power and then Eaton. We sell our UPS systems into a wide range of applications and industries, from IT data centers to hospitals to food manufacturers to offshore oil platforms. Although the applications and requirements may differ across industries, their core need is the same: the uninterrupted operation of critical systems.

Q: How would you assess the market situation and prospects?

A: We can very confidently say that the secure power solutions business is a long term growth opportunity. Why? Because of the sheer amount of digitization that is going on, for one. Just think of how many servers a massively accessed application like Facebook must need, for example. And these computers all need to be protected against power disturbances in order to be available 24/7.

Manufacturing is increasingly high-tech and automated, which is another key driver. And the world’s increasing energy demands are driving investments in energy infrastructure – from extraction right through to transmission and distribution.

In this latter sector, the critical control systems for offshore platforms, pipelines, substations, etc, all need to be power protected. And there are also increasing opportunities in newer energy areas like wind and solar. In fact, the energy sector has grown to become a key contributor to our business – about 20 percent.

Q: Could you give some examples of manufacturing clients?

A: Our systems have been sold into one of the world’s leading solar panel manufacturers, which has a number of plants in Southeast Asia. They need an uninterrupted power supply to ensure all the high precision silicon processing that is performed on the manufacturing line is not disrupted. Process interruptions create huge costs as material needs to be thrown away and production restarted.

Another of our clients, also in Asia, is a major manufacturer of flat panel LED screens. The high-tech production process requires huge amounts of energy and cannot afford to be affected by any form of electrical supply failure.

Q: The power quality across Asia must vary quite considerably?

A: Yes, that’s right. Among the most reliable would be Malaysia and Singapore, which as a result are able to attract businesses that require a high grid quality. But because those tend to be high-tech industries like chip manufacturing, they still need have a need for UPS because of the extremely stringent and sensitive nature of the production process.

Then as you move down to countries like Vietnam, for example, the grid quality is not so good and the industry less high-tech. A typical protection application here would be in a textile factory where there are machines spinning polyester threads. Because of the need to ensure that the threads don’t break, the spinning process should be covered by UPS to mitigate the uncertainty in supply quality. Otherwise, as well as losing production output, you waste time restarting the process and also wear the machines from

all the stopping and starting. But often it’s the case that factory owners will readily spend money on cheap labor but not on protecting the power supply. Because people never think about power, they take electricity for granted: it’s something you plug in, it has to work, why should I think that it will fail, why should I think that the voltage will go up or down?

Something we have observed in Vietnam is milk processors using their own generators for electricity because they cannot rely on the grid. So we are working with some companies to get them to change – because it is much cheaper for them to use the grid plus UPS than to manufacture their own electricity.

Q: So you do see differences in risk acceptance across industries?

A: Yes, that is certainly true. The financial institutions are incredibly risk averse, for example. A company like Goldman Sachs, one of our clients, absolutely does not want to be in a position where it is cannot trade with open positions and will demand the maximum degree of power protection.

In fact, you can say that our business is about how we help our customers manage risk, and we seek to design solutions that reflect their attitude to risk. If you’re exceptionally risk averse then the solution we provide will necessarily quite complex. For companies that can accept a certain level of risk we will design a simpler solution.

The key thing is to listen to customers and to tailor systems that are reflective of their needs. And different countries, different markets, different companies can all require quite different solutions.

Q: The integrity of the UPS unit itself must be an important factor?

A: Yes, because it is supporting a customer’s critical systems then the UPS absolutely has to be working 24/7, 365 days a year. We have a number of service options including, at the highest level, an offering that is unique in our industry: Life.net. This is a remote diagnostics service that actually identifies what is happening inside the UPS itself and transmits the information back to globally located Watchstations.

With Life.net, we can actually produce information and show the customer what has actually been happening at his installation. For instance, we can tell him how many times there was a mains blackout and the UPS was activated. And some of the information is absolutely staggering – we had one unit which experienced 1000 mains blackouts in a year! We are now monitoring over 10,000 UPS units around the world and have 28 Watchstations.

Q: What advances have there been in UPS products and technology?

A: Creating a UPS that can work in tough conditions such as you find in manufacturing has been an important development. A UPS that can operate through zero to 40 degrees centigrade can be sited directly in the production area rather than in a special air conditioned room.

Then there is space. The more space you use in a facility, the more money you use. With recent equipment we have released, we have doubled the power per square meter, which means that that a UPS rating with the same power rating requires half the footprint than previously.

Efficiency of the UPS itself has become a very important point, because that relates directly to the electricity consumption. Five years ago you would typically have a 90 percent efficiency rating for your UPS. Now, Chloride UPSs can deliver 95 percent efficiency starting at 25 percent load, which means that with a very low load, you’re already very efficient. Another environmentally friendly plus point is our UPSs being 98 percent recyclable.

Our latest Trinergy modular UPS system features three functioning modes which are intelligently activated to dynamically respond to electrical network conditions. The most efficient operating mode is chosen to ensure optimum supply to the load and maximum energy savings, using only the necessary energy required to provide the best power quality and conditioning to the load. It’s a new concept for UPS – providing what you need, when you need it, and where you need it.

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The Holistic Approach to Protection

To ensure continuous availability, industrial organizations need to fully understand their critical infrastructure requirements, says Arunangshu Chattopadhyay.

Today’s manufacturing facilities are turning to information technology (IT) to increase efficiency as well as profits. Companies are using technology to better predict demand, track supply, streamline processes and improve customer service.

With powerful equipment, computers and other associated components all networked intelligently for automated processes, powering and cooling these systems has become crucial since any power or environmental disturbance can affect the critical flow of both information and production, resulting in lost income.

Consider the application

The first thing to consider when enabling business continuity in an industrial facility is the application: is it for IT or is it part of the manufacturing process? Once classified, the next step is to identify the issues that impact performance as well as understand how mission-critical power, cooling, and monitoring strategies can enable the equipment to perform optimally.

Likewise, it is important to determine the level of availability the IT or manufacturing equipment requires. Does the equipment need enclosures equipped with a backup supply to provide power during extended outages? Or is the equipment too crucial that it requires continuous power which the grid does not adequately support?

Understanding the application’s impact to the process is an important step in selecting a power system. Take for example a conveyor system that moves materials from one location to another. Although a very common piece of equipment, it is vital to a company’s ability to produce products in a timely fashion because breakdown halts both upstream and downstream processes.

Improve power availability

When designing a power infrastructure, it is important to understand future requirements and ensure a growth plan is in place to cost-effectively meet those requirements. Providing just the capacity required today, with no expansion plan, can constrain future growth, increase operating costs and disrupt operations. As availability requirements rise, various power system redundancy architectures are often implemented to reduce single points of failure, enable future growth and increase operating flexibility.

High-availability UPS systems have redundancy designed in. This redundancy can be achieved through two approaches: symmetrical and asymmetrical. Symmetrical configurations involve two identically sized UPSs operating in tandem to maintain the entire load. Asymmetrical configurations use one UPS large enough to power the entire load, and one or more smaller UPSs to add redundancy to only those devices that must be available continuously.

UPS systems also vary by topology. A true online doubleconversion UPS provides the best performance and protection against all power disturbances. This topology provides continuous power conditioning as well as instantaneous battery backup, and is recommended for all critical single-phase and three-phase applications, particularly high-availability, 24x7 applications such as data centers, laboratories, control rooms, process control, utility systems, motors and drives, server rooms, telecommunications, security systems and clustered cash registers.

Protect against surge

Having an assured power supply for your mission-critical equipment is just a step toward protecting your investment. It is also important to protect your power system with transient voltage surge suppressors (TVSS). Lightning and other transient voltage are harmful to most UPS equipment and to its served electronic load equipment. According to IEEE’s recommended design/ installation practices, facilities housing heavy electronic load equipment of any type should have service entrances equipped with effective surge protection.

Selecting a TVSS device should be based on understanding the system that needs protection. It’s important to determine whether TVSS devices are a viable solution to your specific power quality needs. Also, it is essential to use TVSS devices that are manufactured according to the applications they’re designed for.

Take centralized view

Many of today’s IT systems are designed with a distributed architecture, and end users assume a similar approach to power protection should apply. Assigning a UPS backup at the device level may be the easiest approach for smaller facilities. But as the number of UPS units located throughout the facility grows, managing them to keep the devices protected becomes riskier and less practical. Instead of providing protection at the device level, end users may want to consider a centralized clusterized approach to power protection.

For smaller facilities, this may mean providing a single, large UPS directly downstream of the automatic transfer switch (ATS), while larger facilities may require multiple critical branches with a single large UPS on each branch. In either case, a centralized UPS which resides upstream of power distribution can provide protection for multiple devices in the facility, creating a power protection that is more reliable, more scalable and more manageable than the distributed approach.

To help determine whether an existing facility has reached the limits of the distributed approach, end users may ponder these questions:

• Can the facility, especially critical systems, including cooling resources, be without power for 10 seconds while waiting for the generator to power up during a utility outage? What is the impact of the outage on customer confidence?

• Does a maintenance plan exist to keep multiple UPS units throughout the facility well monitored and maintained?

• Will equipment and systems that require UPS protection continue to be added, rendering a device level approach more costly?

Improper power distribution can actually inject disturbances into your network. Converting and delivering power throughout a facility is an important step in protecting availability. Power distribution products are available to ensure the delivery of clean, high quality power from a UPS or power conditioner to vital systems. Likewise, static transfer switches provide for fast, seamless switching between UPS systems in applications where redundant UPSs are utilized.

Remove the heat

Protecting sensitive electronics from downtime doesn’t end when the power enters the equipment. All of the power used by electronic systems is transformed into heat within the equipment. Unless that heat is removed, it can shut down the equipment that produced it.

Electronic equipment has a low tolerance range for heat. According to cooling best practices, using building air for critical industrial equipment is problematic because it is not designed for continuous, 24x7 duty. Frequent breakdowns and sequential interruptions are the result. Where the building air runs by 8x5 duty, overheating and equipment failure increase dramatically during off-cycle period. Further, these units do not provide filtration and humidity control, both attributes to sensitive electronics.

Cooling electronic equipment takes specialized equipment capable of handling high sensible heat loads and humidity on a year-round basis, with sufficient airflow to break up the concentrations of heat around tightly packed electronic equipment. Temperature control will help prevent equipment damage from both excessive temperatures as well as wide temperature cycles. Controlling relative humidity is also important. Too much moisture can cause corrosion of circuitry while too little will increase static electricity that can short out and damage components. In addition, proper air distribution is required to prevent localized hot spots.

Employ maintenance services

Maintenance is extremely important as it provides a continuous health check of a facility’s power and cooling system. Maintenance helps discover, diagnose and avert looming problems.

During maintenance, power to the critical load may be interrupted or power that is distributed to the load may be unconditioned, depending upon system design. Power systems can be designed to allow maintenance work without disrupting power to protected equipment. Such example would be Emerson’s microPOD which allows manual UPS bypass, powering the connected load with utility power during UPS maintenance or replacement to ensure continuous operation of critical computer equipment.

To ensure continuous availability, industrial organizations need to fully understand their critical infrastructure requirements and apply the optimal solution for their business. They must adequately protect their missioncritical operations through integrated power and cooling coupled with proper maintenance services.

Arunangshu Chattopadhyay is Power Product Manager, Emerson Network Power, Asia.

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