Power conditioning is imperative for any industry or manufacturing unit with dreams of maintaining its competitive edge or making it big in the international arena or even in the domestic market place. Power conditioning is a well-defined strategy to ensure that an enterprise has continuous power availability, which is clean, steady, and free of irregularities. It also encompasses power redundancy in terms of backup and alternate supply.
Power conditioner, also known as line conditioner, is a device that sits between the power supply and the machine or mechanical instrument and protects it against power surges or spikes or brownouts. In the case of the latter scenario, a power conditioner also maintains a continuous voltage fed to the computer during temporary voltage reductions. Power conditioners also can filter EMI emanating from a power source and can smooth the rhythmic cycle of alternating current.
Line conditioners are designed to smooth out spikes, sags and remove EMI/RFI and harmonics from the line. Some UPSes (uninterruptible power supply) have line conditioning as an integral subsystem, while others require an external system to be effective.
These are the typical power-related problems commonly encountered in developing economies like ours. That’s not to say that developed economies are free from such afflictions. Lightning strikes, industrial equipment, high current household appliances, and a variety of other events, the mains supply can vary a great deal from its nominal value. But considering the huge demand-supply gap commonly witnessed in developing economies the quality of power generated might not be first class. Hence, industries need to have a few tried and tested strategies in place to counter such eventualities.
Household appliances might not be seriously affected by power surge or drop. But when the scenario is applied to an industrial setting then the magnitude of the issue is multiplied manifold. For instance, any industry, which relies heavily on automation and computers for the smooth handling of processes, can suffer data loss. A sudden outage can result in data corruption. It can even result in system seizure, as microchips are ultra-sensitive to such fluctuation.
Hence, it should come across as no surprise that the term power outage can give nightmares to any operational manager worth his salt. Any form of outage in an industrial setting can result in huge losses. Loss of productivity is the biggest concern. A manufacturing unit rushing to meet a deadline cannot afford outages at the critical final juncture of production, as this could lead to customer dissatisfaction. Issues that are more tangible include loss of revenue and loss of transactions.
Enterprise power conditioning is a subset of Business Continuity Management (BCM). BCM's goal is to provide 100 percent business uptime, of which power conditioning is an important aspect. This is because electricity is the basic necessity to run the hardware and the applications, which enable a business.
Another survey jointly conducted by Emerson Network Power (ENP) India, and Feedback Consulting in 325 Indian enterprises showed that over 60 percent firms experienced power disruption more than once a month. This means that enterprise India is losing multiple crores of rupees annually in direct losses due to poor power quality and operating environment related downtime. The final bill could be much higher if the indirect losses are taken into account.
System downtime may be the result of various factors including network failure, hardware crashes, earthquakes, floods, and fires. But according to the "Cost of Downtime" survey conducted by Contingency Planning Research Inc., power-related problems were the most frequent reason for outage in an enterprise.
The survey also showed that, power outages took place 25 percent of the time, and power surges/spikes three percent of the time. Together, they comprised the most common outages, and were followed by storms, floods, hardware errors, and fire. Network outages occurred only two percent of the time.
Anomaly in electrical supply is usually unnoticed, perhaps because electricity works silently and invisibly. But a lot can go wrong with it. The main power irregularities come in four flavors-- surges, sags, spikes, and outages.
A surge is a lengthy increase in the supply voltage. A sag or brownout is a similarly lengthy decrease. By and large, most machine power supplies deal with both these common problems quite well. But it does depend on the severity of the irregularity and the quality of the power supply, and how much of its capacity is being used. However, the closer to maximum capacity a power supply is, the less likely it is to handle a given surge or sag. So it is generally advisable to install a power supply with a higher capacity.
Outages are plain old blackouts. An industry unit may probably get away with little or no damage in such a scenario. At the most, there might be a minor system corruption if the power drops out. But is the outage happens in the middle of a sensitive engineering work or in the case of the textile industry in the middle of weaving it could mean a lot of wasted effort in correcting the design or even reworking the entire process.
Spikes, however, are the most dreaded of the lot. A spike is a brief increase in the supply voltage. But in that brief instant, a spike can easily subject your machinery to several hundred volts. This can severely damage not only the system but also the power supply and other components. A few spikes like this could put the entire system out of the running.
Other common problems include EMI/RFI, switching transient, harmonic distortion, wrong wiring, or ground faults. Electro-magnetic interference/radio frequency interference may occur due to electromagnetic noise from devices like printers, radio transmitters, and industrial equipment. It may cause mysterious hangs and other problems. Instantaneous ender voltage (tapering off), which is shorter than a spike and may occur for a nanosecond. It can result in quirky computer behavior and puts stress on components, which can lead to premature failure. Distortion of the normal power waveform. This happens due to the use of variable speed motors, disk drives, copiers, and fax machines. It can cause communication errors, overheating, and hardware damage. Wiring may be deployed incorrectly, but the equipment may work when plugged in. The equipment will face the risk of shock and early failure. Faulty earthing of equipment. This can cause mysterious malfunctions and destroy network equipment seemingly, without explanation
Direct strikes to power lines are rare, because, by definition, a power line is well isolated from earth, and the lightning is looking for an earth. Buried power and telephone lines are a different story, though; lightning strikes a long way away can result in large induced spikes on these sorts of cables.
It is claimed that simply tying a series of ordinary overhand knots in the cable can arrest lightning surges in power or phone cables. Allegedly, the knots do a nifty induction trick when the cable tries to pass super-high voltage, and burn out, saving the equipment. The physics behind this is not nonsense, but there is still considerable controversy over whether or not knots do any good in the real world. They certainly don’t stop ordinary lower voltage spikes. But it would be more advisable to invest in proper power conditioning gear.
UPS (Uninterrupted Power Supply) is the core component of a power conditioning strategy. It has features like the inverter, voltage stabilizer, and EMI/RFI filters. It also has a number of built-in intelligent features, which take care of most of the typical power-related problems. UPSs can also be managed remotely. And this provides a lot of flexibility.
There are two main types of UPS’, differentiated by how they handle power prior to a power loss. There are units that are online all the time -- thus, all power supplied to the data center flows through the UPS first. Due to this filtering, these systems provide conditioned power and there is no switching time associated with converting from "street" power to UPS power.
The second type of UPS is often termed a "standby" unit, as it is offline until the power fails and then there is time associated with switching from street to UPS power. This switching time may only take milliseconds, but there are some devices that are so sensitive that they can crash during that time.
All things being equal, an online UPS is recommended for critical data center power. In sizing the UPS, take into account how long you want to keep the systems up plus how long it takes to do an orderly shutdown.
But one has to look beyond a UPS in order to deploy a total power conditioning strategy. An enterprise also needs to plan redundancy and backup at various levels of operation. Redundancy should also be built into each zone and into all pieces of equipment. Ground faults and wrong wiring issues have to be dealt with. And the success of the solution has to be reviewed through audits and checks.
Besides, older UPS’ do not usually take care of all the power-related problems. For example, a UPS must have an isolation transformer (to protect from EMI/RFI noise) in its output circuit to qualify as a power conditioner.
An ideal power conditioning strategy
It is difficult to suggest a generic strategy that would fit verticals across businesses. But an ideal strategy should leverage a broad framework, which encompasses all power-related problems. Most enterprises have a backup generator set. Hence it would be advisable to have an automatic transfer switch at the power entry point, which will switch between the two power feeds—the regular power supply and the generator. Though a manual transfer switch can be installed, it would mean investing in additional manpower. An automatic transfer switch also comes in handy in the case of remote locations.
Also, power from the transfer switch flows into a surge suppresser controlling any high power fluctuations that are likely to damage equipment.
AC power should pass through the UPS, which has a battery backup and automatically switches over to the alternative supply in case of outages. The power is now distributed to various departments and sections of an enterprise through a power distribution cabinet. Some telecom switches and equipment require DC supply. In this case, the company needs to set up DC power systems and interfaces.
The operational manager should ensure that the cables are robust and the conduits and pipes must be laid according to safety principles. The embedded AC/DC power supply is also critical. This is the power supply grid present inside servers, switches, and other devices. Critical hardware should have dual power grids, so that one acts as fail over.
The enterprise should also evaluate and identify the critical areas for which uptime needs to be enhanced. There may be possibility of distribution faults or some fault in the facility. An enterprise can deploy dual power supplies, dual distribution equipment, and static switches at the load end.
The capability to monitor operations from remote locations has emerged as an important feature for any solution. So, all these solutions should allow browser-based monitoring. Information of impending failures like a weak battery bank and alarm conditions which need manual intervention, can be retrieved from anywhere in the world.
Some management software can also send SMS and e-mail messages as alerts. The remote monitoring and message delivery functions should be closely integrated with the customer's backend network.
As a part of a complete power solution offering, all the equipment has to be wrapped around by services. Servicing starts right from pre-sales and carries on as a life-long commitment made by the power vendor to its customers.
The only use a true UPS has for mains power is to charge its battery. Its inverter runs all the time, so there’s no switchover time if the incoming power drops out. Proper UPSes have to have high quality inverters, which produce an output waveform as close as possible to a sine wave.
Online UPS protection provides the highest level of power quality protection, power conditioning, and power availability. In an online UPS, the inverter supplies conditioned AC power to critical equipment even when the mains supply is not available. And raw power from the main source is used by a rectifier-cum-battery charger to power the inverter. The load equipment will never receive raw power from mains in any condition.
Offline UPS protection, also called standby, is a cheap and cost-effective choice for small, non-critical, and stand-alone applications. In this configuration, mains raw power is continuously supplied to the load till it is available. The inverter is normally off. The inverter will start only after the mains power fails and there is a relay changeover with a small break in output power. The break in power is normally shorter than that required to stop or reboot the computer operation.
Line-interactive UPS protection provides effective power conditioning, which is better than offline or standby UPS and backup. This is particularly suitable in areas where power outages are rare, but there are wider and frequent voltage fluctuations. In this configuration also, power is normally fed by mains but through a voltage stabilizer. The inverter runs and supplies power only during mains failure conditions.
The chief surge-clamping component in a basic filter-board is a Metal-Oxide Varistor (MOV). MOVs pass current only when the voltage across them is above a set value, and they react very quickly (in a matter of microseconds, against the tens of milliseconds a circuit breaker takes). That’s the good news. The bad news is that MOVs wear out - they’re only good for a few uses, and the bigger the spike, the more damage is done.
Cheap power filters seldom give you any indication whether your MOV is alive or not. If the powerboard has an illuminated power switch, the switch light often goes off when the MOV has died. The switch lights generally last for decades, so no light almost definitely means no MOV - but since the light only shows the status of a fuse, and the fuse won’t blow if the MOV has been killed by lots of smaller surges, the light can keep glowing merrily when the MOV has long since kicked the bucket.
Anti-spike gear may also include gas arrestor tubes, which are far more durable than MOVs but too slow for computer applications, or silicon avalanche diodes, which give much of the robustness of gas tubes with the speed of a MOV. The best spike suppressors have all three components, but you won’t find those at the hardware store.
Line conditioners do everything a surge suppressor does, but does it better, and often also boost the output voltage during sags. They’re considerably more expensive than a simple suppressor, because they include a honking great transformer - which makes them satisfyingly heavy - and some chunky capacitors. These components provide some degree of outage protection.
Provided the filter components are good, an SPS will do for domestic purposes. Since it isn’t running its inverter all the time, but only when the power goes down, it can afford to use a lower quality and much less expensive inverter
The best solution is to use precision cooling systems, which work around the clock and are customized for a particular enterprise. In data centers and server rooms, conditioned air should be pumped in from vents on the floor or ceiling to maintain free air flow. Handheld digital thermometers can be used near servers and racks to check local temperatures. Some line conditioners can handle a lightning strike without any problem, some marginally so and others not at all. Make sure that your power systems are capable of protecting your electronics.
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