Power disturbances, even outages, are more common now than ever before, and their occurrences are only likely to increase. The effects can devastate any data being processed, a totally unacceptable situation in today’s information-driven business world.
To eliminate, or at least mitigate, the impact of power disturbances, a variety of filters and uninterruptable power supplies is available. But before you buy any of this equipment, carefully evaluate the sources and characteristics of the disturbances. Establish what is causing your power disturbance: Is it source related or load related?
The drive toward deregulation of the utility industry contributes to source-related problems. The 1992 Energy Policy Act forces utilities to make transmission lines available to unregulated cogenerators, independent companies who sell electric power to large users. This decreases the utility company’s control to optimize power transmission over its lines and to minimize transients due to load switching.
Anticipating more competition due to further deregulation, utility companies are implementing cost-cutting procedures, such as contractual arrangements with customers to curtail their power access during peak demand hours. Both arrangements—transmitting cogenerated power and active peak-period load balancing—entail many more switching events, which can cause even more sags, surges and spikes on your power line.
Load-related disturbances occur as more and more power is consumed by electronic equipment using switch-mode power supplies. These supplies represent nonlinear loads, causing power-factor degradation and potentially inducing high-frequency interference.
To determine the nature of the power disturbances affecting your equipment—and select the appropriate protection—it is necessary to quantify the type of interference coming from your utility company and those caused by other loads at your facility. There are a number of power analyzers available to simplify this task, a selection of which are featured in the following product section.
New Products
Autoranging Analyzer Performs
Simultaneous Measurements
Model 5100 Single-Phase and Model 5300 Three-Phase Power Analyzers simultaneously display true rms values of volts, amps and watts of any DC through 20-kHz signal. Integrating and power-factor measurement features are provided. Multiple ranges extend to 50 A and 600 V for single-phase and 100 A and 600 V for three-phase. The built-in IEEE-488 interface and Windows-based PA-TEST software offer enhanced data analysis and diagnostic capabilities. Magtrol, Inc., (800) 828-7844.
Single-Phase Power Analyzer
Has DC to 250-kHz Bandwidth
The PM100 Analyzer measures all power parameters, including power factor, crest factor, inrush current, frequency to the 50th harmonic and THD. Voltage/current accuracy is +0.2%; power accuracy is +0.4%. A high-resolution backlit LCD presents alphanumerics, waveforms and bar graphs, and facilitates cursor measurements. Integration enables measurement of time-dependent variants. Special application modes, such as electronic ballast testing, are included. Optional plug-in interface modules provide IEEE-488.2, RS-232 serial, parallel printer and chart recorder/alarm outputs. Voltech Inc., (508) 881-7329.
Power Quality Analyzer Is
Housed in Hardened Enclosure
The Power Platform PP1-R Analyzer is designed for remote long-term monitoring and measures parameters needed to perform power quality, energy, and harmonics analyses. Communication is accomplished through its PCMCIA-compatible plug-in slot which supports Ethernet, a modem or RS-232. The card slot also supports removable data-storage devices. Analysis, functioning within the access capability of Windows for Workgroup and Windows NT, is facilitated with the user’s software or the company’s Software for Windows. Dranetz Technologies, Inc., (908) 287-3680.
Power Software Facilitates
PC-Based Analysis
The DETECTIVE PC Edition Power Line Monitor operates as a stand-alone unit or reports events directly to a PC. Up to 1,500 time-stamped power line events can be stored in the summary memory. The included DOS-based HOST software, featuring pull-down window-style menus, automatically transfers data to a hard drive. Presentations, including pie and bar charts, describe disturbances such as spikes, voltage sags and surges, dropouts and common-mode noise. PowerTronics, (800) 746-9586.
Harmonic Energy Analyzer
Weighs Less Than 2 lb
The 3030A Single- and Three-Phase Harmonic Energy Analyzer and Data Logger performs line-disturbance analysis, demand analysis and harmonic energy analysis. As a line disturbance analyzer, the 3030A tracks and logs voltage and current disturbances (up to 999 events). Amplitudes, transient durations and waveform rise times are continuously logged. As a demand analyzer, the 3030A tracks power consumption, energy cost, true watts, kWh, rms volts, amps and power factor. As a harmonic energy analyzer, it tracks %THD and up to the 50th harmonic. Valhalla Scientific, (619) 457-5576.
Harmonics Meter and Analyzer
Feature Three Display Modes
The Model 40 Power Harmonics Meter and Model 41 Power Harmonics Analyzer measure voltage, current, frequency, power, power factor and harmonic distortion. Measured signals can be viewed as a waveform display, a bar graph indicating levels of harmonics present and percentage of each, and the numeric value of measurements. Readings are updated three times/s; minimum, maximum and average values are recorded. Model 41 stores eight measurement setups and features an isolated RS-232 interface. Fluke Corp., (800) 44-FLUKE.
Analyzer Meets IEC-555,
IEC-868 Requirements
The 2503AH 3-Channel Power Analyzer measures and displays V, A, VA, VAR, true power, inrush current, form factor, power factor, crest factor, THD and flicker per IEC-555 and performs harmonic and spectrum analysis. Input voltage ranges from 15 V to 1,200 V rms and current from 50 mA to 40 A rms for frequencies from DC to 500 kHz. Resolution is better than 0.05% of the full-scale range. Three input channels have separate digital signal processors. Digital and analog I/O is provided. Xitron Technologies Inc., (619) 458-9852.
Harmonic Generation/Analysis
System Provides Versatility
The HGA Harmonic Generation and Analysis System measures voltage, power, apparent power, power factor and THD. Harmonic analysis is performed with a bandwidth of 3,300 Hz. The peak reading capability can be set to measure inrush or repetitive peak current. A Windows-based GUI includes various measurement screens and harmonic-analysis display formats. Application-specific software is available for automatic limit testing. The unit is self-contained and programmable via RS-232 or IEEE 488.2 SCPI. California Instruments Corp., (800) 4AC-POWER.
Copyright 1995 Nelson Publishing Inc.
August 1995