Steps to prevent power problems from becoming serious

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Steps To Prevent Power Problems From Becoming Serious
A common belief among facility executives is that designing for good power quality is an expensive process. Unfortunately, through value engineering, power quality planning often is pushed aside because it's not seen as a problem that needs immediate attention.
As the world relies more on data-processing and other digital equipment, facility executives are going to see more problems - such as equipment downtime, systems failure, loss of data or data corruption and, perhaps, tenant loss.
To stop power quality problems from becoming serious, facility executives can follow five steps.
1. Know Your Loads
Regardless of whether you operate an existing building or a new facility, it is essential to understand what types of equipment will be used in the facility and if building equipment is sufficient to handle the loads. Does your tenant have a computer on every desk? Will an uninterrupted power supply (UPS) system or backup generator be installed? Are other sensitive systems, such as medical equipment, a part of the tenant's operations? Even the type of office furniture the tenant uses can have an effect on systems design because each office furniture system has a different way of delivering power.
Understanding the system requirements in turn affects how electrical systems are planned. The most prevalent strategy is to separate the loads. Mechanical systems are located on one line; sensitive equipment, such as computers, is located on another line; and miscellaneous building loads are on a third. Systems designers also need to know, for example, how many cubicles are to be connected, if enough outlets are available to complete the job appropriately, and how equipment is going to be arranged.
Facility executives also may want to limit the types of equipment a tenant can install to prevent disturbances to other tenants' equipment. For example, the owner may require 12-pulse drives if the tenant uses variable frequency drives because they produce lower harmonic distortion than six-pulse drives. Or, if a UPS system is used, the owner may require the tenant to install a filter on the input side.
2. Reduce Harmonics
Harmonic currents are one of the most serious power quality problems facing facility executives. Left unattended, harmonics can cause computer problems because of voltage waveform distortion (called flat topping), as well as reduce equipment life by overheating cables, motors and transformers. Ironically, harmonics often are caused by equipment installed to improve building operation and efficiency, such as electronic lighting ballasts and adjustable speed drives. However, the main cause of harmonics is from the computers themselves, which have switched-load power supplies.
The first line of defense against harmonics is a robust electrical system designed to take the hits. K-rated transformers, oversized neutrals, line reactors and harmonic filters all can make electrical systems stronger to combat or cancel out harmonics. Including this equipment is essential when designing new facilities. The challenge, of course, is in retrofitting existing buildings. Before applying solutions, however, facility executives should first conduct a power quality survey to determine the problem.
A power quality survey involving the measurement of harmonics within a system can help determine the quality of supply voltages, as well as the sources of offending harmonic currents. Depending on the case, the solution may be to attack the problem at each source, which can be costly, or to provide a system-wide solution. But, each case must be reviewed independently.
3. Ground Systems
To ensure optimal performance of the electrical system and its components, as well as sensitive equipment such as computers, and to ensure safety for facility staff, all equipment, outlets and circuits must be connected to the common building grounding system. This limits potential voltage differences be

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Steps to prevent power problems from becoming serious

  1. 1. Steps To Prevent Power Problems FromBecoming SeriousA common belief among facility executives is that designing for good power quality is an expensiveprocess. Unfortunately, through value engineering, power quality planning often is pushed asidebecause its not seen as a problem that needs immediate attention.As the world relies more on data-processing and other digital equipment, facility executives aregoing to see more problems - such as equipment downtime, systems failure, loss of data or datacorruption and, perhaps, tenant loss.To stop power quality problems from becoming serious, facility executives can follow five steps.1. Know Your LoadsRegardless of whether you operate an existing building or a new facility, it is essential tounderstand what types of equipment will be used in the facility and if building equipment issufficient to handle the loads. Does your tenant have a computer on every desk? Will anuninterrupted power supply (UPS) system or backup generator be installed? Are other sensitivesystems, such as medical equipment, a part of the tenants operations? Even the type of officefurniture the tenant uses can have an effect on systems design because each office furnituresystem has a different way of delivering power.Understanding the system requirements in turn affects how electrical systems are planned. Themost prevalent strategy is to separate the loads. Mechanical systems are located on one line;sensitive equipment, such as computers, is located on another line; and miscellaneous buildingloads are on a third. Systems designers also need to know, for example, how many cubicles areto be connected, if enough outlets are available to complete the job appropriately, and howequipment is going to be arranged.Facility executives also may want to limit the types of equipment a tenant can install to preventdisturbances to other tenants equipment. For example, the owner may require 12-pulse drives ifthe tenant uses variable frequency drives because they produce lower harmonic distortion than
  2. 2. six-pulse drives. Or, if a UPS system is used, the owner may require the tenant to install a filteron the input side.2. Reduce HarmonicsHarmonic currents are one of the most serious power quality problems facing facility executives.Left unattended, harmonics can cause computer problems because of voltage waveformdistortion (called flat topping), as well as reduce equipment life by overheating cables, motorsand transformers. Ironically, harmonics often are caused by equipment installed to improvebuilding operation and efficiency, such as electronic lighting ballasts and adjustable speed drives.However, the main cause of harmonics is from the computers themselves, which have switched-load power supplies.The first line of defense against harmonics is a robust electrical system designed to take the hits.K-rated transformers, oversized neutrals, line reactors and harmonic filters all can makeelectrical systems stronger to combat or cancel out harmonics. Including this equipment isessential when designing new facilities. The challenge, of course, is in retrofitting existingbuildings. Before applying solutions, however, facility executives should first conduct a powerquality survey to determine the problem.A power quality survey involving the measurement of harmonics within a system can helpdetermine the quality of supply voltages, as well as the sources of offending harmonic currents.Depending on the case, the solution may be to attack the problem at each source, which can becostly, or to provide a system-wide solution. But, each case must be reviewed independently.3. Ground SystemsTo ensure optimal performance of the electrical system and its components, as well as sensitiveequipment such as computers, and to ensure safety for facility staff, all equipment, outlets andcircuits must be connected to the common building grounding system. This limits potentialvoltage differences between different systems and between different parts of the building.Systems are grounded improperly when voltage on the ground wire varies at different parts ofthe building. This may happen as new equipment is added to the system or as other designchanges are made. Consequences of improper grounding include noise injected into data circuitsby the power system ground or fault currents, and circulating currents in the ground system thatcan corrupt data or cause equipment failure.A good grounding system is the foundation for good power quality. If you dont have a goodground system and you add power quality equipment, you may not see any improvements fromthe equipment you added.In todays world of computers, special grounding considerations also must be made for datacenters and computers. The trend used to be to run separate grounding wires for the sensitiveequipment. But, with networked computer systems, the theory no longer proves valid, and codesrequire that all system grounding wires be tied together.
  3. 3. If facility changes are made, facility staff must go back and look at how systems were groundedoriginally, and then make any modifications as necessary.4. Reduce Voltage FluctuationsWhile not as common as harmonic currents or improper grounding, voltage fluctuations also cancause serious system damage. A similar effect happens to electrical systems when a motor isstarted up or a contact is opened. In these cases, the electrical current spikes, causing a voltagechange in the distribution system that can affect sensitive equipment.Protective equipment such as transient volt surge suppressor equipment can be installed toredirect voltage spikes into the grounding system. However, if a building does not have a goodgrounding system, the transient volt surge suppressor will be ineffective.Motor spikes also can be controlled by limiting the size of the motor across the line and thenusing reduced-voltage starting. However, this practice can be expensive.In some cases, specialty equipment, such as medical X-ray machines, can cause voltage dips.The general practice is to design the systems so that the specialty equipment is isolated from theother building loads.5. Conduct Routine and Preventive MaintenanceTheres an old saying among engineers: If you dont test your systems, nature is going to testthem for you. And, when maintenance personnel get busy, it is easy to forget about the electricalsystem. However, simple care and maintenance can keep your electrical system operatingproperly and reduce power quality concerns.Infrared testing: A "heat" picture of system components shows where components are stressedand what parts ultimately will fail. Testing is conducted by testing associations, certain electricalcontractors and firms specializing in the process.Like anything, testing can be overdone, but you probably want to do the main equipment.Ultimately, the building owner has to decide between the cost of testing vs. the cost ofunscheduled repairs and downtime for tenants. A good testing technique allows you to schedulerepairs because you find the problem early and youre not under a tight schedule to fix it.In-house KnowledgeFinally, we recommend that maintenance staff participate in some type of basic training abouthow the electrical system operates and that maintenance manuals be required in thespecifications. Many projects are delivered with an operations and maintenance manual writtenby project team members. On those projects, team members also may go to the site to providebasic training.Training people who are going to operate the system is as critical as designing the system well.
  4. 4. Power quality is an issue that only is going to be more critical in the coming years. Byaddressing power quality concerns up front, facilities will not only operate better, but tenants willbe happier. Systems need to be evaluated individually for the most appropriate, cost-effectivesolutions. Money invested in good power quality will earn its return through reduced downtimeand improved operations.Julian Arhire is a Manager with DtiCorp.com - DtiCorp.com carries more than 35,000HVAC products, including industrial, commercial and residential parts and equipmentfrom Honeywell, Johnson Contols, Robertshaw, Jandy, Grundfos, Armstrong and more.

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