Accredited Calibration

Why Calibrate?

Measurement instruments can drift over time, even when they continue to operate normally. Temperature variation, component ageing, mechanical stress, and other environmental factors can change measurement performance.

The challenge is that drift is difficult to notice without a reference. An instrument that reads 0.3% high may still appear to function normally, with stable and repeatable readings. But decisions based on those readings are then made against a shifted measurement baseline.

Regular calibration provides a way to detect changes in measurement performance by comparing an instrument with a traceable reference and documenting the result together with its measurement uncertainty.

Measurement error as an engineering risk

Small deviations in voltage, current, phase, or frequency can affect system calculations and test results. For example:

• Voltage: a deviation of 0.1% at 400 V AC corresponds to an error of 0.4 V.
• Current: a deviation of 0.2% at 10 A corresponds to an error of 20 mA. Depending on the application, this may be significant in precision measurements.
• Phase angle: an error of 0.1° can affect calculated power factor, particularly at low power factors.
• Frequency: a deviation of 0.05% at 50 kHz corresponds to 25 Hz and can affect frequency-dependent measurements.

In power electronics and switching systems, higher-frequency components, harmonics, and transients can add further challenges to power measurement. Yokogawa’s European Calibration Laboratory is accredited to ISO/IEC 17025:2017 for power measurements at frequencies up to 100 kHz. This enables calibration at frequencies relevant to applications where power measurements extend beyond the mains frequency range.

Calibration versus adjustment

• Calibration establishes the relationship between an instrument’s indications and corresponding values from measurement standards, taking measurement uncertainty into account. The calibration result provides documented information about the instrument’s measurement performance.
• Adjustment is different. It changes the measuring instrument so that its indications correspond to prescribed values. Adjustment may be performed when calibration shows that the instrument requires correction. After adjustment, the instrument should be calibrated again to verify its resulting performance.

In simple terms: calibration measures performance. Adjustment changes performance.

Understanding measurement uncertainty

A calibration result is not simply a pass-or-fail statement. Measurement uncertainty describes the dispersion of quantity values that can reasonably be attributed to the measurement result. It is an essential part of understanding how much confidence can be placed in a measurement.

For this reason, calibration should not only consider whether an instrument is within its specification. The measurement uncertainty of the calibration itself also matters. A traceable calibration establishes a documented link to a reference through a chain of calibrations, with each step contributing to the measurement uncertainty.

What can cause measurement drift?

Several factors can influence measurement performance over time:

• Temperature variation: changes in temperature can affect components and measurement circuits.
• Humidity: moisture can influence insulation and other electrical characteristics.
• Mechanical stress and wear: connectors, switches, and input circuits can change with repeated use.
• Electrical and electromagnetic stress: operating conditions can influence component performance over time.
• Ageing and storage: component characteristics can change over time, even when an instrument is not in continuous use.

The extent of these effects depends on the instrument, its design, its operating conditions, and its environment. Regular calibration helps identify changes in performance and provides documented evidence of measurement capability.

Calibration at the frequency of the application

For power measurements, calibrating only at 50 or 60 Hz may not fully characterize an instrument for applications involving significant higher-frequency components, such as distorted waveforms. Modern power electronics can introduce harmonics and other high-frequency content as switching speeds increase.

Turnaround and Logistics

An instrument in calibration is temporarily unavailable for measurement work. The process is designed to keep turnaround as short as possible without compromising calibration accuracy.

Turnaround times

• Standard calibration turnaround time: 10 working days from receipt of the instrument. Return shipping time is not included.
• Express calibration: available on request. Contact us for availability and scheduling.
• Fleet calibration (multiple instruments): batched scheduling by arrangement. Enquire for options.

Logistics from the Netherlands

The calibration facility is located in the Netherlands. This has three advantages for customers in the Benelux region and wider Europe:

• Shorter transit times than calibration outside the region
• Secure packaging and transport protocols for sensitive measurement instruments

Why Yokogawa Calibration?

Expertise in measurement. With decades of experience developing precision instruments for electrical and power measurement, we combine our product knowledge with the capabilities of our own European Standards Laboratory to support reliable, traceable calibration.

Experts in our own instruments. We understand how our instruments are designed, how they perform, and what matters in real measurement applications. This knowledge helps us assess their performance with a clear understanding of their intended use.

Quality and value. We combine specialist measurement expertise with a calibration service designed to deliver dependable results at a competitive price. We believe confidence in your measurements should come with clear value for your investment.

What sets Yokogawa calibration apart

• Expertise in electrical power measurement: We have decades of experience developing precision instruments for electrical and power measurement. We apply this expertise to the calibration of power meters, power analyzers, current transducers, and current clamps.
• High-frequency capability: Our accredited power calibration extends up to 100 kHz, supporting applications involving power electronics, switching systems, and harmonic analysis.
• ISO/IEC 17025 accreditation: Our laboratory is accredited by the Dutch Accreditation Council (RvA), registration number K164. Our calibration certificates are internationally recognized under the International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement (MRA), supporting acceptance across participating economies.
• Local logistics in the Netherlands: shorter transit, secure processing, and a familiar documentation environment.
• Predictable turnaround: Standard calibration takes 10 working days from receipt of the instrument. Return shipping time is not included. Express options are available for urgent requirements.

When to choose Yokogawa calibration

Yokogawa calibration is the right choice when:

• Measurement accuracy directly affects design or validation decisions
• You work with power electronics, inverters, or switching systems operating at higher frequencies.
• Your quality management system requires ISO/IEC 17025 accredited certificates with documented uncertainty
• Turnaround time matters and you need a predictable schedule
• You want a calibration partner who understands measurement, not only compliance

Our calibration history

Our calibration laboratory has evolved over more than three decades, from an internal facility supporting Yokogawa’s manufacturing operations to an accredited laboratory serving customers across the industry.

• 1990 Started as an internal calibration laboratory towards ISO9001 for calibrating instruments for the Yokogawa factory. It was in an office environment.
• 1992 Got out of the office environment to an own laboratory room. Then called the ‘Remote Reference Laboratory’ Still calibrating for internal Yokogawa only.
• 1994 Moved to the Yokogawa T&M Service department. Now called the ‘European Standards Laboratory’ and starting calibrating Yokogawa Power Meters for customers.
• 1996 Developed a power calibration system for power traceability up to 1 kHz.
• 2000 The customer calibration’s part was moved to the United Kingdom. Yokogawa bought an Accredited calibration laboratory. In Amersfoort the laboratory did the internal ISO9001 calibrations for the factory
• 2006 The customer calibration’s part moved back again to Amersfoort.
• 2008 The laboratory moved to a new building in Amersfoort. A completely new start was made, building and using new calibration facilities.
• 2012 Traceability for power is now up to 100 kHz under ISO9001. Discission made to go for an ISO/IEC 17025 Accreditation.
• 2015 After three years the European Standards Laboratory gained the ISO/IEC 17025 Accreditation. Including 100 kHz traceability. The first commercial laboratory in the World to do that.
• 2018 Did first comparison in the world for power up to 100 kHz with National Laboratory of Sweden.
• 2020 Build a second 100 kHz Power calibration system.
• 2025 Ten years of Accreditation. And building a 3rd 100 kHz Power calibration system.
• 2026 A new current sensor system build for frequencies up to 100 kHz. Start calibrating none Yokogawa powermeters.  

Explore our measurement and calibration research.
The papers and technical reports below highlight Yokogawa’s work in high-frequency power calibration, measurement uncertainty, interlaboratory comparisons, and the evaluation of power measurement instruments.

A Calibration System for Current Transducers up to 100 kHz

Modern power electronics produce complex current waveforms with higher frequency components. Yokogawa’s European Standards Laboratory has developed a calibration system for current transducers up to 100 kHz and 100 A. The system enables the characterization of ratio and phase performance at higher frequencies and demonstrates the performance of current transducers when measuring distorted waveforms. 

Yokogawa has initiated a comparison on frequency

Several laboratories have joined the comparison to check their calibration systems.
By participating in a comparison, confidence is build for this type of measurements.
Yokogawa has demonstrated a good result.

Evaluation Yokogawa WT310 for standby power measurements

A detailed sample report with calculations on how Yokogawa WT310 digital power meter not only fulfills the requirements of the recent IEC 62301 Ed. 2.0 and EN50564:2011 international standards but also exceeds those by far.

Bilateral Comparison LF Power up to 100 kHz

Nowadays there is more need for traceability for distorted power waveforms. Therefore a power calibration system was developed at the European Standards Laboratory of Yokogawa Europe Solutions B.V. This system has the capability to calibrate electrical power
meters from DC, 10 Hz up to 100 kHz. To evaluate the calibration system traceability, a bilateral comparison was carried out between the Yokogawa European Standards Laboratory and the National Standards Institute of Sweden (RISE).

Calibration: Meeting the challenges of high-frequency power measurement

A white paper descripbing Yokogawa's European Calibration Laboratory's capabilities. The facility is the only industrial (i.e. nongovernment or national) organisation to offer traceability up to 100 kHz, and thus is the only power meter
manufacturer which can directly prove the performance of its own instruments. Only a Yokogawa Calibration Certificate
gives the user trust in their instrument's measurements.

Interlaboratory Comparison LF-Power

Yokogawa participated in an official Interlaboratory Comparison on low frequency (LF) power.
Different accredited laboratories measured an object (a power meter) and the results were compared to reference values. The different laboratories are not shown by name, however the Yokogawa European Standards Laboratory is described as ‘L002'.

Two conclusions can be made from the document.

1. The Yokogawa WT3000 power analyser is proven to have the required accuracy, stability and ruggedness to enable it to be used as the measurement object in this interlaboratory comparison.
2. The Yokogawa European Standards Laboratory has the best stated uncertainties which are thus better than the National Standards laboratory (VSL) in this document.

WT210 More than Meets the Standard for Standby Power Measurement

A detailed sample report with calculations on how Yokogawa WT210 digital power meter not only fulfills the requirements of the recent IEC 62301 Ed. 2.0 and EN50564:2011 international standards but also exceeds those by far.

Yokogawa Europe Sampling Wattmeter for Low Frequencies

A high accuracy power measurement system, based on digital sampling techniques, is being developed at the standards laboratory of Yokogawa in Europe. The system is based on two sampling voltmeters and a synchronization device. Using potential transformers and compensated current transformers with an AC shunt resistor, the uncertainty is less than 20 ppm for active, reactive and apparent power for frequencies between 45 Hz - 60 Hz.

Report comparison on power 53 Hz 2020 

Upon the request from other calibration laboratories within the Netherlands, Yokogawa Europe Solutions B.V. was asked to organize a comparison to Low Frequency Power. The Yokogawa European standards Laboratory has the expertise and reference instruments to do this.

The conclusion of the comparison was that all laboratory measurement agrees with the reference values for the expanded measurement uncertainty and that the Yokogawa WT5000 Precison power analyzer can be used as a traveling standard due to good stability.

Explore our research papers and technical reports
Discover how we evaluate measurement performance, establish traceability and advance calibration capabilities.

A Calibration System for Current Transducers up to 100 kHz
Explore how we characterize current transducers for ratio and phase performance up to 100 kHz and 100 A.

Bilateral Comparison of LF Power up to 100 kHz
Learn how our European Standards Laboratory established traceability for wideband electrical power measurements up to 100 kHz and validated its calibration system through a bilateral comparison with Sweden’s RISE.

Explore our brochure
Discover more about Yokogawa Test & Measurement and our measurement solutions. Download our brochure to explore our instruments, key capabilities and applications.

If you have any questions or would like further information, please contact us yef-nl-csc.calibration@yokogawa.com.

Download Yokogawa Power Calibration Services brochure

1. What is accredited calibration? 

Accredited calibration is calibration performed by a laboratory that has been independently assessed as competent for specific calibration activities. The accreditation applies to the calibration activities, measurement ranges, frequencies, and measurement capabilities defined in the laboratory’s accredited scope.

2. What is Yokogawa’s calibration accreditation?

Yokogawa’s European Calibration Laboratory is accredited to ISO/IEC 17025:2017 under RvA registration K164. The laboratory is located at Yokogawa’s European headquarters in Amersfoort, the Netherlands. Its accredited scope includes power measurements at frequencies up to 100 kHz, with specific measurement ranges and uncertainties defined by the RvA scope.

3. Up to which frequency does Yokogawa offer accredited power calibration?

Yokogawa’s European Calibration Laboratory offers ISO/IEC 17025 accredited power calibration up to 100 kHz within its defined accredited scope. The exact capability depends on the measurement requirements.

4. Where is Yokogawa’s European Calibration Laboratory located?

Yokogawa’s European Calibration Laboratory is located in Amersfoort, the Netherlands. The accredited laboratory is part of Yokogawa Europe Solutions B.V. and operates at Euroweg 2, 3825 HD Amersfoort, under RvA registration K164.

5. How do I request a calibration from Yokogawa?

You can request calibration through our contact us.

6. Why do measurement instruments drift over time?

Measurement instruments can drift over time, even when they continue to operate normally. Changes in components, ageing, temperature, mechanical stress, operating conditions, and other environmental factors can affect measurement performance. Calibration provides a way to characterize instrument performance against measurement standards and document the result.

7. What is measurement uncertainty?

Measurement uncertainty describes the range of values that can reasonably be attributed to a measured quantity. It accounts for the factors that contribute to uncertainty in the measurement result. In Yokogawa’s accredited calibration scope, measurement capabilities are specified together with corresponding measurement uncertainties.

8. Why is measurement uncertainty important on a calibration certificate?

Measurement uncertainty is important because a calibration result is not complete without information about the uncertainty associated with that result. It helps you understand the significance of the measured deviation and assess the result against your required measurement performance. Yokogawa’s RvA K164 scope specifies calibration and measurement capabilities together with their associated uncertainties.

9. Can I check whether my instrument is still accurate enough without calibration?

A functional check can show whether an instrument is operating, but it does not replace calibration when documented measurement performance and traceability are required. Calibration compares measurement results with appropriate standards and provides documented information about the result and its measurement uncertainty. For applications requiring ISO/IEC 17025 accredited calibration, the calibration must also fall within the laboratory’s accredited scope.

10. How often should I calibrate my measurement instrument?

There is no single calibration interval that is appropriate for every measurement instrument or application. The right interval depends on factors such as instrument stability, frequency of use, operating environment, required measurement accuracy, and previous calibration results. Your quality system, customer requirements, or applicable standards may also define a calibration interval.

11. What instruments does Yokogawa calibrate?

Yokogawa provides calibration services for a range of test and measurement instruments, including power meters and analyzers, digital multimeters, oscilloscopes, data recorders, signal analyzers, current clamps, calibrators, and other instruments. The instruments and services covered by ISO/IEC 17025 accreditation depend on the specific activities and ranges listed in the RvA K164 scope. Yokogawa therefore recommends checking the accredited scope for the measurement you require.

12. Does Yokogawa offer high-frequency power calibration?

Yes. Yokogawa’s European Calibration Laboratory provides ISO/IEC 17025 accredited power calibration up to 100 kHz within its defined scope. This capability supports power measurements beyond traditional 50/60 Hz calibration and is relevant to applications involving higher-frequency electrical power.

13. Why is calibration up to 100 kHz important for power measurements?

Calibration up to 100 kHz is important when power measurements are made at frequencies above the traditional 50/60 Hz range. Yokogawa identifies applications such as switch-mode power supplies, high-frequency electronic lighting, motor control, and traction converters as examples where higher-frequency power measurement can be relevant. The RvA K164 scope defines Yokogawa’s accredited power measurement capabilities up to 100 kHz.

14. What does traceable calibration mean?

Traceable calibration means that the calibration result can be related to a recognized reference through a documented, unbroken chain of calibrations, with each contribution to measurement uncertainty taken into account. For an ISO/IEC 17025 accredited calibration, the laboratory’s measurement standards, methods, procedures, and uncertainty calculations are assessed as part of the accreditation process.

15. What is the difference between manufacturer calibration and ISO/IEC 17025 accredited calibration?

Manufacturer calibration and ISO/IEC 17025 accredited calibration are not automatically the same. A manufacturer may provide calibration under its quality system, while ISO/IEC 17025 accreditation provides independent recognition that a laboratory is competent for specified calibration activities. For Yokogawa, the European Calibration Laboratory operates under RvA registration K164, with accreditation applying to the activities and ranges defined in its accredited scope.

16. Can Yokogawa calibrate instruments from other manufacturers?

Yokogawa’s European Calibration Laboratory provides calibration services for a range of measurement instruments, but whether a specific non-Yokogawa instrument can be calibrated depends on the instrument, measurement function, and required calibration service. For ISO/IEC 17025 accredited calibration, the requested activity must also fall within the RvA K164 accredited scope. Contact Yokogawa with the instrument model and required measurements to confirm availability.

17. How does instrument calibration work?

Instrument calibration compares the instrument’s measurement results with values provided by appropriate measurement standards under defined conditions. The results are recorded so that the instrument’s measurement performance can be assessed and documented. Where applicable, the calibration results include the measurement deviation and associated measurement uncertainty.

18. How do I know which calibration points will be included on my calibration certificate?

The calibration points included on your certificate depend on your instrument, the requested calibration service, and the applicable calibration procedure.

To see how calibration results are documented, view our example ISO/IEC 17025 calibration certificates for a selection of Yokogawa test and measurement instruments, including power meters, power analyzers, and current sensors.

19. What is the difference between calibration and adjustment?

Calibration determines the relationship between an instrument’s indications and corresponding values provided by measurement standards; adjustment changes the instrument so that its indications meet specified requirements. Calibration and adjustment are therefore different activities. An instrument can be calibrated without being adjusted, depending on the purpose and calibration result.

20. What is included on a calibration certificate?

A calibration certificate documents the calibration results and the information needed to interpret them. Depending on the calibration service, this can include the instrument identification, measurement conditions, reference standards, measurement results, deviations, measurement uncertainty, and information about traceability. An ISO/IEC 17025 accredited certificate also identifies the relevant accredited calibration activities and scope where applicable.

21. What does k = 2 mean on a calibration certificate?

A coverage factor of k = 2 is commonly used to express an expanded measurement uncertainty corresponding to a coverage probability of approximately 95% under the assumptions of the uncertainty model. The exact interpretation depends on the uncertainty evaluation and the statistical assumptions used. Yokogawa’s RvA scope defines its calibration and measurement capabilities with a 95% coverage probability.

22. What happens if my instrument is out of tolerance?

If a calibration result shows that an instrument does not meet the required tolerance, the next step depends on the instrument, specification, and calibration service. The instrument may require adjustment, repair, or further investigation. After adjustment or repair, a further calibration can be performed to document the instrument’s resulting measurement performance.

23. How long does a Yokogawa calibration take?

The calibration time depends on the instrument, calibration requirements, and service requested. Yokogawa’s European Calibration Laboratory handles a range of calibration activities, so the applicable turnaround time should be confirmed when the calibration is requested. Standard calibration turnaround time: 10 working days from receipt of the instrument. Return shipping time is not included.

24. How is my instrument returned after calibration?

Yokogawa coordinates the return of calibrated instruments through its local service organization. The applicable shipping and return process depends on the country and service arrangement. When requesting calibration, Yokogawa can provide the relevant logistics information for your location.

25. What is ISO/IEC 17025?

ISO/IEC 17025:2017 is the international standard for the competence of testing and calibration laboratories. It covers requirements related to laboratory competence, impartiality, consistent operation, measurement methods, equipment, traceability, and the evaluation and reporting of results. Yokogawa’s European Calibration Laboratory is accredited to ISO/IEC 17025:2017 under RvA registration K164.

26. What is the difference between ISO 9001 and ISO/IEC 17025 for calibration?

ISO 9001 focuses on an organization’s quality management system, while ISO/IEC 17025 specifically addresses the competence of testing and calibration laboratories. For calibration, ISO/IEC 17025 accreditation provides independent recognition of a laboratory’s competence for defined calibration activities. Yokogawa’s European Calibration Laboratory is accredited under ISO/IEC 17025:2017 through RvA registration K164.

27. Will my customer or auditor accept a non-accredited calibration certificate?

Acceptance of a non-accredited calibration certificate depends on the requirements of your customer, auditor, quality system, contract, or applicable standard. ISO/IEC 17025 accredited calibration is often specified when independent recognition of laboratory competence and documented traceability are required. Yokogawa recommends checking the applicable requirement before selecting the calibration service.

28. Why choose Yokogawa for power calibration?

Yokogawa combines power measurement expertise with an ISO/IEC 17025 accredited European Calibration Laboratory in Amersfoort. Under RvA registration K164, the laboratory provides accredited power calibration within a defined scope that extends to 100 kHz. This allows engineers to have calibration and power measurement expertise available from the same measurement partner.

29. What makes Yokogawa’s European Calibration Laboratory different?

Yokogawa’s European Calibration Laboratory combines manufacturer expertise with an ISO/IEC 17025 accredited calibration capability for defined measurement activities. The laboratory is located at Yokogawa’s European headquarters in Amersfoort and its RvA K164 scope includes power measurement capabilities up to 100 kHz. The laboratory also provides calibration for a broader range of Yokogawa test and measurement instruments and services, subject to the applicable scope.

30. Does Yokogawa calibrate its own instruments?

Yes. Yokogawa’s European Calibration Laboratory calibrates Yokogawa test and measurement instruments, including power meters and analyzers and selected other instruments and modules. The laboratory’s ISO/IEC 17025 accredited services apply to the specific measurement activities included in the RvA K164 scope. For example, Yokogawa currently states that power meters are covered up to 100 kHz and that selected ScopeCorder input modules are included in the accredited scope.

31. Why does high-frequency calibration matter for power electronics?

High-frequency calibration matters because power electronics applications can involve electrical signals well above the traditional 50/60 Hz power frequency. Yokogawa identifies applications including switch-mode power supplies, high-frequency lighting, motor control, and traction converters. Calibration at the relevant frequencies helps characterize the performance of power measurement instruments under conditions representative of their intended use.

32. Is Yokogawa’s power calibration ISO/IEC 17025 accredited?

Yes. Yokogawa’s European Calibration Laboratory in Amersfoort is accredited to ISO/IEC 17025:2017 under RvA registration K164, and its accredited scope includes defined power measurement capabilities up to 100 kHz. The exact measurement ranges, frequencies, and measurement uncertainties are specified in the current RvA scope.