Office buildings contain computers, printers, fluorescent lights, telephone systems and other electronic devices that are sensitive to power quality issues, such as voltage interruptions and power transients. Power quality problems can interrupt business, reduce productivity and lead to costly equipment repair or replacement. A number of cost-effective solutions are available to help protect your critical equipment and maintain a productive work environment.
A swell is an over-voltage, while a sag is an under-voltage (a minimum of ±10 percent that lasts from about eight milliseconds, or one-half cycle to one minute). Sags below 10 percent of voltage supply are usually classified as interruptions.
Solutions for voltage interruptions include the following options:
- Battery uninterruptible power supply (UPS). These offer the most complete power protection and are widely used for a variety of sensitive equipment. UPS systems consist of two types: online and stand-by. Standby devices remain idle until a power failure occurs, and then they switch to their own power source. Online units operate continuously, providing backup power as well as power quality protection. UPS systems range in size from a 300 VA (volt-amperes) for a single computer to up to 1,000 kVA (kilovolt-amperes) for the protection of clusters of office equipment or servers.
- Flywheel UPS. During power disturbances, the flywheel continues to spin for a period of time (from 10 seconds up to several minutes). Up to 75 percent of the energy stored in the flywheel is used to continue the rotation of the generator and supply uninterrupted power to the load.
Transients are non-repetitive, brief, over-voltages or waveform distortions in an electrical system. Power factor correction capacitor switching is a common transient source. Transients can disrupt, damage or completely destroy critical electronic equipment. A spike is a commonly occurring over-voltage transient that lasts from nanoseconds to milliseconds. Spike solutions for interruptions include the following options:
- Surge suppressor panels and receptacles use solid-state metal oxide varistors (MOVs) as the suppression element. MOVs are grouped by their voltage rating and energy handling ability. The voltage surge energy is absorbed by the MOV and converted into heat. Repetitive, high-energy surges can degrade MOVs. When equipment has signal/data connections in addition to alternating-current (AC) connections, damage can come not only from the AC side, but from the signal wires as well. Many manufacturers offer models that combine AC and signal line protectors.
- Wall outlet surge suppressors come with six to eight outlets and various indicators, and are available at your local electronics store.
Start with a plan
By developing an understanding of the electrical environment that your equipment operates in, you can uncover ways to improve uptime and increase overall productivity. Start with an investigation of the reason behind any power quality problems you have been experiencing. Has any new equipment been added? Does the problem occur at certain times or only once in a while? Keep a log to help track problems in more detail. A properly designed power protection system that addresses your specific issues is a good investment and can have a quick payback.
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