POWER QUALITY Educational Series: Why Test?

Why Measure Quality? Some of the attributes of PQ as they and making a variety of measurements apply to AC power are shown below. using power monitoring equipment. Based Power Quality (PQ) refers to the reliable on the source and nature of the problem, delivery of electrical energy in a form that Power Quality Problems alternative solutions are developed. enables electrical equipment to operate properly. When dips and swells, spikes, Typical solutions may involve installation surges, momentary outages, sags or other of an uninterruptible power supply (UPS), disturbances occur, computers and other design and installation of filters, removing electrically powered equipment may the external source of interference or the malfunction, fail prematurely or shut down answer might be as simple as transferring unexpectedly. Many facilities simply the load to another circuit or reconnecting cannot accept these consequences. an improperly connected ground or Consider hospitals, banks, data neutral conductor. Here are some communications centers, manufacturing examples of PQ problems and solutions. and other facilities that rely on smooth, Standards that are helpful in measuring reliable power for operations. The and resolving PQ include IEEE 519, 1100, consequences of an unplanned outage 1159, 1346, 493 and 446 (CBEMA Curve). can cost thousands of dollars each Solving Power Quality Problems minute or result in unsafe conditions or other serious problems. The first step is to identify the source and nature of the disturbance or condition What is Power Quality? that is causing the problem. This usually Power quality is a multi-dimensional and involves interviews with facility personnel complex measure, especially as it applies to AC power circuits. PQ encompasses , current, and FACILITY PROBLEM SOLUTION frequency spectrum magnitudes. It can Telecommunication Emergency generators produced Installed filters on generator control circuits involve electromagnetic field measures. Center sags and surges Sudden or gradual changes in any of School Mild shocks and flickering lights Revised grounding connection these measures have a big impact on Repeated failure of critical Hospital Installed transient voltage suppressors power quality. PQ is really a comparison of care monitors the actual to the ideal or desired values of Military Transfer mis-operation Installed power factor correction equipment each of the characteristics of electrical Semiconductor Sporadic tripping of large Replaced breaker trip unit with one less sensitive to power. Unlike current or power, which are Manufacturer harmonic current Electronics measured in amperes and there is Computer monitor "jitters" Installed magnetic field shielding to block EMF's Manufacturer no scoring or measurement unit for PQ. Overload neutral provided high neutral to ground Consequently, terms associated with Distribution Center Servers Failing voltage, possible cause for server power supply power quality refer to the gaps or failure. Installed dedicated circuit for servers. anomalies between the actual and desired values. Desired attributes of PQ are therefore negative terms; no dips, no spikes, no sags, no surges, no outages, etc.

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