Power conditioning isn't new but it's a technique that is only really appreciated by a part of the system and product design community. Kevin Beavan describes a new service for designers that allows genuine power protection to be designed into systems where the more traditional external products are either inappropriate for commercial reasons, or less effective for technical ones
A power conditioner protects electrical equipment from power disturbances. It eliminates problems like voltage spikes, electrical noise and power-cuts that disrupt services, stifle productivity and cost money. Typical power conditioning units range from 78VA to 500kVA and contain an isolation transformer, surge diverter, noise filter, uninterruptible power supply (UPS) and data line protection
A simple way to understand the function of a power conditioner is to compare it to the fuel filter that is found on an automobile engine. Without the fuel filter, large particles and other contaminants in fuel would find their way into the automobile engine causing damage and ultimately engine failure. In much the same way, a power conditioner contains elements that prevent electrical contaminants from damaging or destroying a sensitive computer-based system.
Different from UPS?
While a UPS provides back-up power in case of power supply failure, a power conditioner eliminates electrical disturbances entirely. Uninterruptible power supplies eliminate power-cuts, but in spite of many manufacturers' suggestions, most aren't capable of preventing other power problems at all. The UPS must be used with the other parts of the power conditioning system to achieve total power problem immunity. A properly designed uninterruptible power supply or UPS will contain the same elements as a power conditioner
The industries served by power conditioning suppliers in the UK include medical imaging, clinical and analytical diagnostics, information technology/telecommunications, semiconductor manufacturing and testing, industrial automation, retail, robotics, digital printing and graphics. They are typically running systems that are inherently expensive to operate because they use delicate, unique materials (medical samples for example) or expensive materials, but the application of power conditioning sensibly extends to any computer-based system where down-time costs money. The key to complete immunity to power problems is using the right combination of devices for your application.
Power headaches
Two examples of power problems that power conditioning eliminates are voltage spikes and impulses, which result from electrical equipment inside the facility. Electrical loads like lifts, air conditioning compressors, relays, presses, pumps, induction furnaces, printers and copying machines can cause sudden large increases in voltage inside the electrical system. Conditions outside the facility can be to blame, too. Switching activities by the electricity supplier and lightning strikes can cause transient impulses so intense they literally 'blow up' sensitive micro-circuitry. This problem can be deadly to electronic systems - but not always immediately. Sometimes voltage spikes and impulses are relatively small in amplitude. In these cases it acts like a virus, weakening the system components over time and leading to deteriorating health and eventual unexplained failure. Other times the impulses may be so large that they cause immediate system failure
A second problem is electrical noise, also generally created inside the facility by the system's electrical neighbours. Again the automobile is a good analogy. Just as automobiles create pollution by burning fuel, every electrical device creates 'electrical pollution' as a by-product of using electricity. Photocopiers, laser printers, and electronic lighting ballasts are all noise sources that can cause computer-based terminals to lock-up, lose data, or behave unreliably. Even computers themselves generate electrical noise. It's truly a paradox that our computers often infect other computers with power viruses. Although European directives help reduce electrical noise to an acceptable level, in most cases there is still enough to be a problem in most installations.
Voltage regulation is characterised by abnormal variations in the electrical circuit's nominal operating voltage (230 volts, for example). These variations are generally greater than +10% of nominal voltage and may last for several line cycles or more. Traditionally this power problem is referred to as the 'sag' or 'swell'. It is typically caused by large loads turning on and off and overloaded branch circuits or distribution transformers. In some cases, voltage regulation can be accomplished by the system's power supplier. If an electronic system requires tightly regulated voltage (fortunately most of today's computer-related products don't), the voltage regulation problem is likely to cause system lock-ups and unreliable operation in addition to damaged or destroyed components.
A standard electronic engineer's headache, common-mode voltage, is now relatively easy to spot and more system problems are being traced to its existence. The condition is characterised by unwanted voltage measured between neutral and ground. It results from high impedance safety grounds, neutral conductors shared with other circuits, and branch circuit lengths that are excessive - all very common in a modern retail installation. The common-mode issue has the ability to cause lost files, system lock-ups or re-boots, communication errors, and those 'no problem found' service calls.
Power-cuts are the most visible and easily identifiable of all the power problems, and they have the most obvious cause and effect. This is especially true if the system is a network or some other 'fault intolerant' architecture. In spite of what most UPS manufacturers advertise, blackouts account for comparatively few occurrences of all the power problems; indeed, less than 0.1% of power related failures.
Evolved power conditioning
The problem with standard off-the-shelf power conditioners is that they may not meet all the defined tolerances and standards for power quality that electrical equipment requires. New technology applications frequently demand a power conditioner with special capabilities or performance specifications. What if the power protection solution needs to be built into an existing space inside a system, or divided among several parts of the same system? Many applications need special, customised features of some sort that standard packaged power conditioners do not offer.
To meet these requirements without reverting to first principles, power conditioning specialist, PowerVar has introduced a custom-engineered offer to system designers, which allows proper power protection to be designed into systems where external products may be impractical or where they may cast a poor impression on the vendor's main installation. The company will adapt designs to manufacturing requirements so that power conditioning can be integrated within the customer's products. - effectively customising power conditioning products to meet very specific needs.
For example, a manufacturer of mobile trolleys used in the US healthcare industry required a dc-to- dc uninterruptible power supply with multiple dc outputs to power several computer peripherals such as tablet PCs, printers, and wireless Internet modems. In addition, the power supply needed to have its own internal battery charger, a long discharge nickel-metal-hydride battery pack, software connectivity to the host PC, and safety agency listing to the requirements of IEC60601 and UL60601. This integrated power supply module needed to fit specific physical size, weight, and dimension requirements of the mobile trolley design. PowerVar's custom engineering team designed a single, integrated charger/UPS with long runtime capability that fitted the physical, operational, communication, and safety agency requirements of the manufacturer. The company now manages the manufacturing and production of the product for the trolley manufacturer.
Power conditioning isn't new, but in parallel with the drive to cut power consumption worldwide, overall tolerance to power-related problems is falling. Designers are therefore using power conditioning to maintain reliable operation and to protect product reputation.
Kevin Beavan is managing director of PowerVar UK