Power Analyzer: The Swiss Army Knife of Electronics Testing
At the heart of every device, appliance, and piece of industrial equipment running our modern world is the electrical power supply keeping it alive. The quality of the power flowing through their circuits is the invisible factor that controls how reliably they perform on any given day.
So power quality analysis is an essential and critical prerequisite in the testing of every electronic project and device. Engineers must ensure that the power supplies or power converters inside devices run perfectly for years under any condition.
For this crucial task, engineers rely on power analyzers. In this article, learn what these workhorses of the testing world can do and how they are used for different use cases.
What is a power analyzer?
A power analyzer is a multi-functional measurement instrument used to analyze the electrical power quality of direct current (DC) or alternating current (AC) systems.
A power analyzer optimizes cost and space by combining the capabilities of multiple instruments in a single package. The instruments that it can replace include:
- Power meter: A power analyzer can measure power consumption, efficiency, and power quality.
- Oscilloscope: A power analyzer can capture and display voltage and current waveforms in real time.
- Digital multimeter: A power analyzer can measure instantaneous voltage and current like a multimeter.
- Waveform generator: A power analyzer can generate arbitrary analog waveforms to simulate various electrical conditions.
- Data logger: A power analyzer can record measurement data over time and transfer them to a computer for detailed power analysis.
- Power supplies: Some can work like power supplies to send power to the devices under test (DUTs).
- Electronics loads: Some power analyzers can act as electronic loads to sink current, which is useful when the device being tested is a power supply.
Fig 1. A power analyzer does the work of multiple instruments for power analysis
Power analyzers are versatile instruments that enable engineers and hobbyists to analyze the behaviors of all types of power supplies and power converters.
How does a power analyzer differ from a power meter?
Both power meters and power analyzers are used to characterize power systems. But as explained above, power analyzers combine multiple instruments under one package. In a typical test setup, power meters are rarely used standalone and more often in combination with multimeters, waveform generators, oscilloscopes, loads, and data loggers. Power analyzers pack all of them into a single instrument to enable compact, convenient, end-to-end test setups.
Types of power analyzers
Power quality analyzers are categorized based on their AC/DC capabilities as:
- DC power analyzers: They are suitable for analyzing the DC outputs of DC power supplies, DC-DC converters, and AC-DC adapters.
- AC power analyzers: AC power analyzers are used to characterize the outputs of AC power supplies, DC-AC converters, and AC-AC converters. Since AC signals may have DC components, AC power analyzers are typically capable of analyzing DC signals too. Single-phase analyzers are more common, but three-phase power quality analyzers are available as well to verify the overall power quality and individual phase power of three-phase devices.
The AC and DC use cases for power analyzers are depicted below.
Fig 2. AC power analyzer use cases
Fig 3. DC power analyzer use cases
What are the key capabilities of power analyzers, and what parameters can they measure?
Earlier, we described power analyzers as multiple instruments in one package. In this section, we explore their versatile capabilities that justify that description.
Power measurements and quality analysis
Power analyzers combine the capabilities of power meters and digital multimeters. They can measure:
- voltages (max, min, average, and peak-to-peak) with high accuracy
- current, using current probes such as current transducers, AC/DC current clamps, and shunts
- electrical power in watts
- apparent power (volt-amps)
- reactive power (VAR)
- power factor
- true root-mean-square (RMS) voltage and current, even if your waveform is non-sinusoidal and has DC offsets
- phase angle
- voltage crest factor
- current crest factor
- impedance losses
- energy efficiency
Oscilloscope functions
To help diagnose power quality issues, power analyzers can act as oscilloscopes with typical scope functions. They can:
- support multiple isolated analog input channels, typically from two to four
- visualize real-time voltage and current waveforms
- be set to single-shot mode to capture high-speed transients
- set triggers
- apply math functions
- enable AC or DC coupling
- support floating inputs
For example, the PA2201A IntegraVisionAC power analyzer can sample signals at rates of 5 million samples per second with a bandwidth of 2.5 megahertz (MHz).
Supply power with arbitrary waveforms
To simulate various power conditions, power interruptions, transients, and power disturbances, power analyzers can act as power supplies with built-in arbitrary waveform generators.
Data logging
Power issues and their diagnoses can often get too complex to do directly on the instrument. That's why power analyzers have real-time data logging and reporting features to act like simple data acquisition devices.
The power logger's measurement intervals can be configured from a few microseconds to minutes, even hours, with millions of samples recorded per data log. Additionally, the duration of logging can range from seconds to as much as a year on some devices. These readings can then be exported to an external computer for more in-depth offline analysis.
Electronic loads
Some power analyzers can sink current to act as electronic loads with dynamic load profile configurations. This enables the stability testing of power supplies, power converters, and battery chargers under variable load conditions.
What are some industry use cases of power analyzers?
Let's understand how the basic capabilities described above are combined for higher-level use cases in different industries.
1. Power quality, consumption, and efficiency analysis
Power analyzers assist in power quality analysis, reduction of power consumption, and improvements in energy efficiency for a variety of power systems:
- power conversion systems and components like AC and DC power supplies, DC-DC converters, DC-AC inverters, AC-DC power adapters, solar inverters, and transformers
- battery management systems
- power control systems of electric vehicles, hybrid electric vehicles, and plug-in hybrid electric vehicles
- uninterruptible power supplies
- satellite power systems
- electrical systems that run on mains power
Additionally, power analyzers enable:
- transient testing of automotive electronic control units as well as satellite and defense applications
- characterizinginrush currents when devices are switched on
Harmonic analysis
Fig 4. A complex wave is decomposed into its harmonics
Harmonics are electrical currents or voltages with frequencies that are integer multiples of the fundamental frequency of the power system's standard waveform, which is usually the main power grid's frequency of 50 or 60 hertz (Hz).
What is the importance of harmonic analysis in power systems?
Harmonics appear as distortions in the power signal caused by non-linear loads, like switch-mode power supplies, and can lead to a variety of power quality issues. Harmonic analysis helps to improve the designs of power systems.
How does a power analyzer assist with harmonic analysis?
Fig 5. This example of a harmonics measurement shows that the 15th harmonic is too high to meet the stated standard for grid power quality.
The following capabilities of power analyzers help identify signal integrity issues fromharmonics:
- Waveform sampling: Power analyzers can capture high-frequency waveforms at a high sampling rate for accurate harmonic representation.
- Frequency domain analysis: The scope functions enable the decomposition of waveforms into fundamental and harmonic frequencies to analyze power quality.
- Real-time visualization: The on-screen display of waveforms and harmonic content enables immediate observation and issue identification.
- Accurate measurements: Power analyzers support the measurement of voltage and current harmonics and the total harmonic distortion (THD).
- Standards compliance: Power analyzers have built-in compliance checks with international standards like the International Electrotechnical Commission (IEC) 61000-3-2 standard forharmonic emissions.
- Data logging: Data logging enables engineers to analyze trends in the power behavior and assess their long-term impacts on the power grid.
3. Power factor analysis
The presence of large-scale inductive loads (for example, in manufacturing industries that use heavy-duty induction motors) results in phase differences between the supplied AC voltage and current waveforms. This leads to high reactive power and higher current consumption without any useful work done.
What is the significance of the power factor?
A lagging power factor is undesirable for power utilities as well as customers. The high reactive power results in resistive losses for the power utilities and costlier power bills for customers. So power factor correction techniques are applied to reduce the reactive power.
How is the power factor measured using a power analyzer?
Power analyzers support continuous wave analysis and report a variety of power factor metrics like:
- AC and DC real power
- AC and DC apparent power
- AC and DC reactive power
- AC and DC power factors
- AC and DC power angles
What features should be considered when selecting a power analyzer for specific testing or measurement needs?
Here are some of the features and specifications you should pay attention to for different use cases:
- AC and DC capabilities: Select a power analyzer that is compatible with the nature of the DUT and the AC/DC nature of its input and output signals.
- Frequencies and harmonics of the signals: Ensure that the bandwidth of the power analyzer is sufficient to capture the harmonics of the signals. As a rule of thumb, the bandwidth should be three to five times the maximum fundamental frequency to accurately capture its higher harmonics and waveform shape. For example, the PA2203A 3-phaseAC power analyzer has a 2.5 MHz bandwidth, which is sufficient for capturing the 400 Hz AC signals used in avionics. For switch-mode power supplies that typically operate in tens of kilohertz (kHz), a power analyzer with about 200kHzbandwidth is sufficient to capture their harmonics.
- High accuracy for digital circuits: For analyzing power supply to sensitive digital circuits like field-programmable gate arrays, use power analyzers with high accuracy and high digits of resolution.
- High-voltage safety features: Verify the tester's safety ratings to ensure that it's designed to handle high voltages and currents. For example, for high-voltage AC power analyzers, look for safety ratings like "1000 V CAT IV," which means the device can safely handle 1,000 volts and is compliant with the IEC's CAT IV safety standard.
- Connectivity options for offline analysis: For complicated diagnoses that require a lot of data from the data logger, ensure that the power analyzer has high-speed connectivity options like gigabit ethernet rather than slower options like Bluetooth.
- Calibration: Ensure that the power analyzer's results are accurate and reliable by regular calibration with ISO/IEC 17025 certification.
Benefits of power analyzers
Since power analyzers pack the capabilities of multiple devices in one instrument, it has several benefits like:
- More convenience and productivity: Wiring up a power analyzer to a DUT is far less complex and much faster than connecting a waveform generator, a power meter, an oscilloscope, and a data logger.
- Lower purchase costs: Buying one instrument in the place of five lowers your purchase costs.
- Reduced maintenance and calibration costs: It also saves you long-term costs because maintaining and calibrating a single instrument is far cheaper than doing it for five.
Rely on Keysight Power Analyzers
In this article, we explored the versatile capabilities of power analyzers — the Swiss Army knives of test and measurement — and how they optimize costs and complexity for various power analysis use cases.
Keysight's powerful DC power analyzers and AC power analyzers come with long-term warranties for your peace of mind. An extensive set of technical support resources are available as well to help your power analyses.
Contact Keysight for help with picking the right power analyzer for your needs.---