• Gossen Metrawatt
  • Gossen
  • Camille Bauer

Questions and answers about calibration

  • Why Calibrate?

    For standard calibration in the DIN EN ISO 9000-9004 series of standards, the essential feature of the QS element is test equipment monitoring. Test equipment monitoring should ensure that all test equipment that is relevant for product quality measures "correctly".


        • The measuring equipment must be ... calibrated or verified at specified intervals ... (ISO 9001: 2000, section 7.6)
        • According to DIN VDE 0701-0702: 2008: "The measuring instruments used for the repeat test must be regularly checked and calibrated"
        • "The contractor must ensure that the electrical systems and equipment ... are checked for their proper condition at certain intervals ... (Excerpt from §5, (1) of the accident prevention regulation BGV A3)
        • To ensure this, the test equipment must be periodically calibrated and traceable to national standards.
        • Furthermore, the determined measured values ​​must be documented. The return of the calibration results to the national standards has already been certified by the user in a standard "factory certificate".


    ILAC = International Laboratory Accreditation Cooperation
    EA = European
    Cooperation for Accreditaion
    DAkkS = German Accreditation Body

    However, the international recognition of such certificates has become increasingly questionable due to the enormous increase of partially unqualified calibration service providers. As a result, ISO9000 inspectors are increasingly demanding calibration certificates from calibration services that are accredited EA or accredited in the EA or in the ILAC, or only in other European countries.
     The DAkkS is accredited as a German member organization of EA and therefore enjoys unrestricted acceptance in EU countries.

    Our DAkkS calibration laboratory is in accordance with DIN EN ISO / IEC 17025

    Thus it is determined that all required conditions are adhered to the competence of the service provider. The DAkkS laboratories personnel are checked for their abilities and are constantly monitored. Furthermore, the technical conditions (for example, measurement uncertainties) are known and publishable.

  • What is calibration?

    Calibrate means the detection and documentation of the deviation of the display of a measuring instrument from the correct value or the output variable of a test instrument from the nominal value.

    Thus, a measurement is made in which the device under test is compared with the values ​​of an accurate and returned normal according to a documented procedure. The goal is to identify and document deviations.

    If the display of a measuring instrument, or the output variable of a test instrument is located at the calibration outside the permissible tolerances, there are two possibilities:

    • It is readjusted so that the values ​​are within the allowable tolerances and then recalibrated.
    • It deliberately dispenses with the adjustment because the user would like to have documented the measurement deviations of his measuring device, or of his test equipment, in the case of long-term use over defined time intervals.
  • What is Adjustment?

    Adjustment is the process by which a device is adjusted or adjusted in such a way that the measurement deviations from the reference value are as small as possible and within the device specifications. Adjustment is a process that permanently alters the measuring device.

  • What is traceability?

    Traceability describes a process by which the displayed measurement value of a measuring instrument can be compared to the national standard for the measured variable via one or more steps.

    Establishment of the connection to the national state institute PTB

            • Establishment of the connection to the national state institute PTB
            • Ensuring the feedback of the measured quantities to the SI units
            • Calibration of the standards of use, both of the on-site calibration stations and the inspection equipment monitoring center


    The on-site test sites under the Permanent Calibration Laboratory are:

              • Calibration of measuring instruments and calibrators - At these locations, calibrations are either performed as part of the final inspection as standard in production or by the service as a single calibration
              • Calibration of special metering equipment e.g.- Shunt with current-voltage method
              • -High resistance 30 GOhm with VM=1000V

    Repatriation and Organization of our DAkkS Calibration (Hierarchy of Normals)

  • Who benefits from the DAkkS calibration certificate?

    All customers who have implemented an ISO 9000 QA system. This is especially true for smaller companies because the devices can be used as a benchmark for multimeters and handheld calibrators.

    Of course also for calibration service providers They are particularly valuable for all final test stations where adjustment, adjustment and calibration work is carried out.

    Even businesses who need to verify the proper condition of electrical equipment have the assurance that their test equipment relevant to product quality will measure "correctly" and nationally Normal are traceable.

  • DAkks calibration certificate or factory calibration certificate?

    Very often the question is asked, when compared to the DAkkS calibration, cheaper factory calibration would be sufficient as a recalibration measure.

    Factory Calibration Certificates are created with standards that are subject to regular inspection equipment monitoring; the return of the standards used is ensured by regular inspection equipment monitoring.

    Factory calibration certificates can be considered sufficient if the calibration accuracy of the measuring and test equipment is important, but the facilities do not serve as standards

    DAkkS calibration certificates are issued with standards whose returns are guaranteed by DAkkS certificates or by calibration certificates of the DAkkS laboratories. DAkkS calibration certificates can only be issued by DAkkS accredited calibration laboratories as part of the accredited measurement quantities. This ensures that high quality calibration is achieved through regular auditing, returned standards, well-defined ambient conditions and specially trained personnel. These cost and labor intensive measures result in a higher price, but also the necessary reliability in the measurement results.

    However, when recalibrating gauges, which in turn serve as standards for monitoring other gauges and test equipment, a DAkkS calibration should be used because of the assured return to national standards.

  • Which calibration interval is recommended?

    In order to be able to carry out permanently correct measurements, the test equipment used must be monitored or calibrated at regular intervals. This period corresponds to the calibration interval.

     A frequently asked question is about the necessary calibration intervals for measuring and test equipment. There can be no clear answer to this, since a calibration is always a snapshot and this u.a. depends on the following factors:

    • Measured variable and permissible tolerance band
    • Use of measuring and test equipment
    • Stability of past calibrations
    • Required measurement accuracy
    • Determinations of the required accuracy of quality assurance system in the companies

    This means that the distance between two calibrations must ultimately be determined and monitored by the user himself. 

    Our recommendation for the calibration interval is 1-3 years. In order not to leave the customer alone with the possibly expensive determination of the interval, we offer a consultation by our coworkers. 

    Our factory calibration certificates are at dated for recalibration at one year intervals. Deviations must be specified by the customer in the order or on the delivery note.

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