HIOKI Improves High-Frequency Power Calibration Accuracy and Frequency Range by 10 Times

Overview

Developed a new measurement standard for evaluating the high-frequency power measurement accuracy of power analyzers.

Using a proprietary calorimeter method, achieved an uncertainty of 0.006% of apparent power at 200 kHz and 0.014% at 1 MHz for effective power calibration.

This research result has been published in the international academic journal "IEEE Transactions on Instrumentation and Measurement" in the field of electrical measurement. (*1)

Center: Proprietary "Calorimeter," Left and Right: Power analyzer and current sensor under calibration

(*1) M. Nakamura, "Calibration of Phase Error for a Wideband Precision Power Analyzer Using the Calorimetric Phase Standard," in IEEE Transactions on Instrumentation and Measurement, vol. 75, pp. 1-10, 2026, Art no. 1003610, doi: 10.1109/TIM.2026.3687333.

HIOKI (HIOKI E.E. CORPORATION: Ueda City, Nagano Prefecture, President and CEO: Takahiro Okazawa) has developed a new measurement standard to be used as the reference for power meter error calibration, aiming to solve the long-standing issue of insufficient accuracy in high-frequency power calibration (*2). This measurement standard achieves approximately 10 times higher calibration accuracy compared to conventional technologies, including methods used by national metrology institutes.

This technology utilizes the physical principle that power loss appears as heat. The method using our newly developed calorimeter can detect minute heat generation of less than 0.01% of input apparent power, with almost no influence from operating frequency.

In conventional electrical calibration methods, calibration uncertainty (*3) decreases as frequency increases. On the other hand, thermal measurement is characterized by being less susceptible to frequency effects. The calibration method using the new calorimeter developed by our company achieves extremely small uncertainties of 0.006% of apparent power at 200 kHz and 0.014% at 1 MHz by continuously correcting for ambient temperature fluctuations and external heat input.

At high frequencies like 200 kHz, even existing national standard class calibration methods have an uncertainty of 0.05%, which means our accuracy is approximately 10 times higher.

This uncertainty corresponds to about 9 mW at an apparent power of 150 VA, a negligible value equivalent to the power consumption of a capacitor. Therefore, it can provide highly reliable measurement results even in fields where efficiency improvement is crucial.

Smaller uncertainty means higher reliability of measurement results.

(*2) Calibration of measuring instruments refers to measuring the error of an instrument against a reference standard using a certain reference measurement standard.

(*3) Uncertainty is an indicator that shows the possible variation or error in a measured value. Smaller uncertainty means higher reliability of the measurement result.

Quoted from research paper: Mechanism of the newly developed calorimeter (left) and internal structure of the calorimeter (right)

Furthermore, by calibrating the effective power measurement error of HIOKI's power analyzer PW8001 combined with the current sensor CT6904A using this measurement standard, we confirmed that the error up to 200 kHz is less than 0.04% of apparent power. This is a region of such high precision that it was difficult to sufficiently verify with conventional measurement standards.

Using the calorimeter, the error in the combination of power analyzer PW8001 and current sensor CT6904A was calibrated. The plot represents the calibrated value, and the bars indicate uncertainty. The red dotted line is an example of uncertainty in conventional national metrology institutes (NMI). Because the developed method has small uncertainty, it can detect slight errors that are difficult to detect with conventional methods.

Efforts toward High-Accuracy Power Measurement

This achievement has been realized amidst the evolution of power electronics technology, which controls energy flow in applications such as electric vehicle motors, solar power conditioner, wind power generation, and data center power supplies, towards higher switching frequencies and smaller energy losses. As the efficiency of equipment improves, the losses that engineers need to measure are becoming smaller and smaller. Therefore, there is a growing need to calibrate the accuracy of measuring instruments with higher precision over a wider frequency range, requiring measurement standards that are even more accurate than the measuring instruments being calibrated.

We intend to utilize this measurement standard as a foundational technology supporting the accuracy of broadband power measurement. In the future, we plan to expand into calibration services using this technology, further advance measurement technology, and contribute to the high efficiency and reliability improvement in the power electronics field, including electric vehicles, renewable energy, data centers, and industrial power supplies.

As the global power electronics market expands and energy regulations become more sophisticated, increasing efficiency requirements, the ability to verify high-frequency performance with traceable accuracy provides a significant competitive advantage for customers' product development.

Contribution to the Power Electronics Field through Our Evaluation Standards

We are committed not only to providing high-precision measuring instruments but also to advancing measurement standards that support the reliability of measurement results. Through reliable measurements, we will contribute to innovation in the power electronics field and the realization of a sustainable society.

Paper Information

Paper Title: Calibration of Phase Error for a Wideband Precision Power Analyzer Using the Calorimetric Phase Standard

Author: Miyuki Nakamura

Publication: IEEE Transactions On Instrumentation and Measurement

DOI: 10.1109/TIM.2026.3687333

Paper URL: https://ieeexplore.ieee.org/document/11494752

(This paper is licensed under a Creative Commons CC BY. The content of this press release is a modified version of the content of this paper.)

Links

Technical Note

Calorimetric Calibration Technology for Wideband Low Power Factor Power

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About HIOKI E.E. CORPORATION

We provide electrical measurement solutions for various fields, including automobiles, electronic components, environmental and new energy, and infrastructure. Electrical measuring instruments, referred to as the mother tools of industry, are indispensable in all situations, such as research and development, production lines, and maintenance services. With solid technology and unique innovation cultivated through our sole focus on electrical measurement since our founding in 1935, we promote the safe and effective utilization of energy for our customers and contribute to the peace of mind and development of society. Through speedy collaboration between our Japanese headquarters, which integrates development, production, and management functions, and our domestic sales bases and group sales companies spread across Asia, America, and Europe, we provide timely solutions to customers worldwide.

Company Name: HIOKI E.E. CORPORATION

Founded: June 1935

Business Activities: Development, production, sales, and service of electrical measuring instruments

Head Office: 81 Koizumi, Ueda City, Nagano Prefecture

https://www.hioki.com/ja