GTM has gone one further on the way to the precise measuring of torque and efficiency in wind power plant test rigs:
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The complete re-accreditation of the GTM Calibration laboratory by the German accreditation body (DAkkS) was successfully completed in June.
The calibration laboratory was credited with competence as a competence assessment body in accordance with DIN EN ISO/IEC 17025:2005 (accreditation certificate dated June 29, 2012); accredited for calibrations in the areas:
In the interest of ongoing further development and improvement, the re-accreditation process included the assessment of two proprietary procedures, which were added to the service offering.
The calibration procedure GTM-RL-002 "Calibration of Multi-Component Systems" provides comprehensive calibration processes for multi-component systems of any model type, which are used for determining forces and torques. These may be decoupled, partially decoupled, or monolithic systems. Typical systems for calibration are measuring platforms for spring testing. The result of the calibration is the description of the uncertainty vector as a calculation rule. With it, the user can calculate the relevant measurement uncertainty for any load situation. The calibration describes for the calibration object the characteristics linearity, repeatability, hysteresis, remanence, zero point return, and behaviour under mixed loads. In addition to these contributions, an uncertainty contribution is added to the overall measurement reliability.
Technical progress is based on seven years of experience in calibrations in the area of multi-component measurement technology. The newly developed calibration procedure represents an innovative milestone and will be presented to the public at the International Measurement Confederation in Korea in September of this year. The global conference is a meeting point for scientists from national metrology institutes around the world (IMEKO 2012, Busan, Republic of Korea).
The other newly developed calibration procedure GTM-RL-003 describes the calibration of force transducers that are used as reference force transducers in force calibration machines. This procedure will result in a smaller measuring uncertainty for the reference force transducer than in calibrations in accordance with ISO 376. The reduction in measuring uncertainty can usually only be achieved by more costly processes or an assessment better suited for the application. Since the different signals of the reference force transducers are processed electronically in different ways, the guideline shows three different calculation paths for determining the measuring uncertainty.
In case I, the reference force transducer is operated in the measuring equipment with different compensation curves for increasing forces and for decreasing forces. Case II covers applications, in which the reference force transducer is operated with the compensation curve only for increasing forces, and case III addresses applications, in which the reference force transducer is operated with a compensation curve derived from the median values of increasing and decreasing forces.
With these two new procedures, GTM offers calibrations in compliance with six proprietary guidelines and work instructions, and seven standardised guidelines for force and torque.