Power supplies are often taken for granted in electronic system design, although the quality of the power supply is one of the most important parameters for any electronic system. The power and its supply serve as forms of heartbeats for an electronic system and have a great deal to do with the ultimate performance and reliability of the system. The purity of the power in a component or system can be determined by a variety of measurements, using the proper power-quality measurement equipment. Because power purity is usually revealed by the connection of a nonlinear load which will stress a component or system into distortion, it is not something that can be measured with a simple test tool, such as a multimeter, but requires an instrument designed for measuring power parameters even under nonlinear conditions: a power analyzer capable of power quality analysis.
Power quality analysis is a process by which various electrical parameters in a system or component are studied. It can be performed within a suitable power analyzer or by having the analyzer work with a computer and software written to interpret the measured data into meaningful power quality results. Power quality issues are typically caused by single-phase loads on an electrical line, and those same loads, such as motors, transformers, and lights, are subject to damage from “dirty” power. Fortunately, power analyzers are designed to detect disturbances in a power line or supply and help track them down to the source of the disturbance.
Choosing a Tester
Power analyzers are available as larger instruments for permanent installations as well as smaller, more portable units better suited for troubleshooting. The most typical electrical parameters to be measured include, voltage, amperage, frequency, power, variations in voltage and current, power factor, harmonic currents, distortion, and crest factor. Familiarity with the requirements of a power-quality test application can provide tremendous guidance in the selection of a power analyzer, whether it is to be used on a production line or in the field.
In general, a power analyzer will be selected according to its measurement capabilities, such as AC and DC measurement ranges, peak voltage measurement range, and measurement resolution and accuracy for each parameter, in addition to voltage and current unbalance. Additional considerations are for the number of inputs, whether the analyzer can measure single-phase or three-phase power or both. Providing specialized power measurements such as energy consumption, efficiency, voltage sags, and crest factor (CF) can also add to the usefulness of a power analyzer. In addition, an analyzer’s inclusion of digital ports, such as a USB port, for connection to a computer and saving data for analysis.
Carry It with You
Portable power analyzers certainly provide unmeasured flexibility with their capability to be carried to a site and moved about a component or system to be tested. Portable power analyzers such as the Fluke 435-II pack a tremendous amount of measurement power into a compact unit that can be carried to almost any test set. The three-phase power analyzer is equally at home for scientific analysis and troubleshooting, with an AC/DC voltage measurement range of 1 to 1000 V, a peak voltage range of 1 to 1400 V peak, a CF range of 1 to more than 2.8, an amperage measurement range of 5 to 2000 A at 1mV/A, peak amperage measurement limit of 5500 A peak at 1 mV/A, and the capability to measure as much as 2000 MW power at 1 mV/A. The portable power analyzer can vary frequency from 42.5 to 57.5 Hz at 50 Hz and from 51 to 69 Hz at 60 Hz, both ranges adjustable with 0.01-Hz resolution and ±0.1% accuracy. Overall, the small size of this unit is highly misleading compared to the large measurement capabilities, automatic functions, and extremely high accuracy. It can even operate for more than 8 hours on a single battery charge.
Recording and Monitoring
When continuous power measurements are needed at a site or for monitoring the power supplied to a component in a system, the Fluke 1750 Three-Phase Power Recorder is an alternative measurement tool well suited for single-phase and three-phase automatic power quality surveys, power monitoring, and long-term analysis applications. The analyzer provides four input channels for AC/DC voltage measurements and five channels for current measurements and has a built-in 2.4-GHz Bluetooth wireless radio for remote connections. It features self-identifying current probes and voltage connections that work with the recorder for ease of installation, even in tight spots. The lightweight instrument can measure true RMS voltage and current every cycle or as required by applicable power measurement standard. This is a measurement solution for long-term monitoring of a power distribution system or for detecting intermittent problems in a power distribution system.
In a slightly larger package, but with a durable built-in carrying handle for portability, the Tektronix PA4000 Power Analyzer can be specified with one, two, three, or four channels. These are versatile instruments, capable of accepting inputs to 1000 V RMS AC/DC, 2000 V peak, and 1000 A current with standard instrument accuracy of 0.01% for both voltage and current. They can perform measurements on highly modulated waveforms and on crest factors as high as 10. The analyzers can also perform harmonic analysis to the 100th harmonic. Multiple personal computer (PC) interfaces for transferring data include USB drives for convenience and speed in storing measurement data.
Testing Power Abroad
For a truly international touch to power measurements, the Hioki PW3198 Power Quality Analyzer is available with seven different display languages for use in different countries. It measures, records, and analyzes single-phase and three-phase AC and DC supplies with as many as four channels. The analyzer is easy to read with a large 6.4-in. color LCD screen to simplify examination of measurement results and features a large amount of internal memory for performing and recording continuous measurements. It is available with a host of clamp-on current sensors and many voltage wiring adapters for three- and four-wire systems.
These analyzers represent a small sample of the measurement solutions for power quality measurements on the Axiom Test Equipment website. Any choice of power analyzer should be guided not only by current measurement requirements but anticipated future needs in terms of capabilities and performance, and such factors as portability or lab use. More information, including data sheets for any of the instruments mentioned above, can be found by visiting Axiom’s website at www.axiomtest.com, contacting Axiom Test Equipment’s sales department at firstname.lastname@example.org, or by calling an Axiom sales representative at 760-806-6600.