European calibration laboratory receives accreditation

08 December 2015

Yokogawa’s calibration lab in Amersfoort, Netherlands is the first non-government facility to receive ISO17025 accreditation for power measurements up to 100 kHz.

To receive the full accreditation from the Dutch accreditation council, Yokogawa spent 3 ½ years demonstrating and documenting the capabilities of the laboratory to demonstrate they could achieve high accuracy results.

Engineers need to be confident that the measurement tools they are using meet the exact requirements of modern design. Power meters need to be calibrated at certain frequencies, depending on the application and at more than just 50 Hz. Frequency is just one factor that Yokogawa’s calibration laboratory is addressing. The power environment today needs to address other factors outside of frequency, such as phase shift and the effects of distorted waveforms. These factors are all highlighted within Yokogawa’s instrument specific sheet, providing the evidence needed to reassure customers that its instruments perform within the required specification. 

The calibration system compromises of two parts, a signal generator section and a reference measuring unit, both of these are separated by a metal shield in order to prevent the heat generated by the signal sources affecting the calibration. 

The Primary Calibration System can achieve high accuracy results on measurements between 50-60 Hz, with a best uncertainty of ±30 part per million (ppm) even at a small power factor of 0.0001. This system was mainly designed for the large transformer industry, to measure power loss. The laboratory can also achieve high current calibration up to 1200 Arms at 50-60 Hz, with an uncertainty of ±37ppm on ratio and ±0.0025° for the phase angle.
 
The in-house development software makes the calibration laboratory very flexible, the system is able to communicate with a power meter under calibration by GPIB, RS232, USB or Ethernet. A typical calibration of a power meter can be completed within a matter of hours. 

No measurement can ever be 100% accurate; there will always be unknown factors between the measured value and the true value. However, Yokogawa have taken steps to minimise the unknown factors and products now have an estimated 8x increased accuracy from the European calibration laboratory, depending on the application. For example, the laboratory is humidity controlled, with a constant room temperature of 23°C and a special air-conditioning unit to maintain that temperature. The laboratory is also fitted with special fire detectors due to the large amounts of electrical equipment, immediately able to send an alarm if smoke is detected. 

The calibration laboratory’s accreditation allows Yokogawa to test and certify its own instruments, not only power meters but oscilloscopes, recorders and optical products and provides the company with essential development tools for the future. Yokogawa’s customers can have confidence that all its instruments provide access to traceable power calibration, helping them to avoid costly submission with national standards laboratories. 


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