Analyze AC/DC Power for the Highest Quality

Electric AC/DC power is increasingly required in daily life, including for electric vehicles (EVs). Power and its quality from various supplies, such as charging stations, must be established and maintained through appropriate measurement cycles, and power analyzers and power quality analyzers are among the best equipment for regularly checking on power supplies and how well they are performing. The basic difference between the types of units is that power analyzers measure power while power quality analyzers measure the quality of power over time.

Finding an AC/DC electric power measurement solution can take time, due to the large assortment of performance parameters associated with power and power quality. Fortunately, by understanding the needs of an application for electric power, selection of the optimum measurement tools for power analysis can be simplified and how well a power supply meets the requirements of a particular electric load can be determined.

Power analysis involves measurements of key electrical parameters, such as voltage and current, at desired probe points along a circuit. Power quality analysis gauges how continuously and consistently those parameters are maintained over time. Units for evaluating power and power quality may share many AC/DC electrical test capabilities, but power quality analysis typically requires some means of measuring, capturing, and storing substantial amounts of measured data over time. Test data may be analyzed and displayed within a power quality analyzer with sufficient computer processing power and software, or with the aid of an external computer with its own software.

A power quality analyzer typically provides greater numbers of measurements during a test session than a power analyzer. While power analyzers such as the model PA3000 from Tektronix provide the precision needed for detailed analysis of individual power parameters in various circuit wiring modes, power quality analyzers such as the model 1750 power quality recorder from Fluke automatically measure over 500 power quality parameters for a circuit or network. Power analyzers measure individual power parameters manually or automatically while power quality analyzers are multifunction measurement systems, with several equipment working together. Power quality analyzers typically perform a host of measurement functions during a test sequence and may perform those measurements over some designated time to assess the electric power quality. To do so, power quality analyzers often combine such units as power meters, harmonic analyzers, and transient-disturbance analyzers, controlled by extensive computing power, memory, and software. As a result, over time they can execute automatic measurements of the many parameters that determine AC/DC power quality.

Adding an Analyzer

The Tektronix PA3000 is an example of a power analyzer, available with one to four measurement channels for evaluating essential electronic characteristics such as voltage, current, and power with high accuracy and resolution. Suitable for power measurements during the research and development (R&D) of new electronic products, it can determine key power-related specifications such as energy consumption and power efficiency according to domestic and international standards. It can measure as high as 30 A RMS current and 600 V RMS (2000-V peak) voltage with ±0.04% accuracy across a 1-MHz bandwidth. The power analyzer samples input signals at a rate of 1 MSamples/s sampling rate using a 16-b analog-to-digital converter (ADC). It shows measurements on a full-color display and connects to an external computer via local area network (LAN) and Universal Serial Bus (USB) interfaces with GPIB available as an option.

Also in a flexible, modular configuration and with a 10.1-in. front-panel color touch-screen display, the Yokogawa WT5000 Precision Power Analyzer can be adapted to measurements as needed with seven rear-panel slots for plug-in modules. The mainframe incorporates Ethernet LAN, USB, and GPIB interfaces, and one mainframe can serve as the master controller for as many as three slave units for complex, multipoint measurements.

The power analyzer, which can be equipped with as much as 32 Gb internal memory, can capture to the 500^th harmonic. It can be fitted with modules capable of measuring as high as 5 or 30 A current, with the two different types working at the same time, and with modules measuring AC and DC voltage as high as 1000 V. Impressively, the basic accuracy of voltage, current, and power measurements is ±0.03% using an 18-b ADC operating at 10 MSamples/s across a 10-MHz bandwidth. It is a good fit for such applications as measuring power in EV power trains, in solar-power inverters and in wind-power conditioners.

For basic single- and three-phase power analysis, the Chroma 66204 is a digital power meter in a half-rack mainframe which can be configured for measurements on two-, three-, and four-wire circuits. It can be equipped with as many as four input modules for standard voltage measurements as high as 600 V RMS (and to 1200 V RMS with an optional kit) and current measurements as high as 20 A RMS. It includes GPIB and USB interfaces for remote control.

Pondering Power Quality

When not just power levels but the quality of the power must be known, a suitable power quality analyzer can provide test data for evaluation. Test equipment such as the Fluke 1736 and Fluke 1738 Three-Phase Power Loggers automatically capture and log over 500 power quality parameters over selected time periods. Measurement functions include voltage, current, frequency, power, power factor, and total harmonic distortion (THD). Voltages as high as 1000 V RMS can be measured and current ranges extend from 1 to 150 A through 6 to 600 A, with 10× scaling available to increase all current ranges. For lower-current measurements, probes are also available for 40 mA to 4 A, scaled from 400 mA to 40 A. For characterizing power quality over time, averaging intervals from 1 s to 30 min in duration can be selected. Voltage and current can be measured at frequency bandwidths from 42.5 Hz to 3.5 MHz. Measurement ease and accuracy is aided by Fluke Energy Analyze Plus software included with each power logger as well as the company’s Fluke Connect® mobile communications application software which remotely controls over 500 power quality parameters.

For measurements of three-phase power quality over time, the Fluke 1750 Three-Phase Power Recorder is a combination power quality analyzer and data recorder without a display screen. It provides wide-ranging measurements of such parameters as power quality, harmonics, and  power over time but relies on an additional personal digital assistant (PDA) for control and display via a wireless communications link. The recorder can be left at one spot in an application, with simple voltage connections and automatically scaling current probes, while an operator can be mobile and check on automatic measurements using a handheld PDA. The recorder contains sufficient internal flash memory to store more than one month of test data for long-term power quality measurements. Data from the recorder mainframe can be downloaded onto an SD memory card or transferred directly to a computer via Ethernet interface.

For on-site power quality analysis, the Megger MPQ1000 Power Quality Analyzer is a highly capable portable measurement tool with impressive computing power built into a handheld package. It is a three-phase power quality analyzer with sufficient memory for recording extended periods of power analysis data; its small size makes it possible to bring to almost any application. Data interfaces include USB and Ethernet. The compact but powerful unit provides eight channels of power quality analysis with 16-b resolution across a 1-MHz bandwidth, with voltage ranges of 1000 VAC RMS and ±1500 VDC and current measurement limit of 6 kA.

More information, including data sheets, on any of these power analyzers and power quality analyzers is available from the Axiom Test Equipment site (www.axiomtest.com). Also, account managers at (760) 806-6600 are always happy to fit either a power analyzer or a power quality analyzer to the needs of an application.