For example, refer-ence 135 gives the results of a round-robin test series performed under the
sponsorship of the IEEE High Voltage Test Techniques subcommittee. The
paper describes the results found when two reference dividers were circulated
to a number of laboratories, each having a Measuring System thought to be
adequately calibrated in accordance with the previous version of IEC 60-2.
The study revealed significant discrepancies in some laboratories between the
results obtained with the Measuring Systems currently in everyday use and
the Measuring System using the reference divider which was being circu-lated. Based on these findings, the concept of Reference Measuring Systems
was introduced with the aim of improving the quality of high-voltage impulse
measurements.
A Reference Measuring System is defined in IEC Publication 60-2:1994
as a Measuring System having sufficient accuracy and stability for use in the
approval of other systems by making simultaneous comparative measurements
with specific types of waveforms and ranges of voltage or current. The require-ments on a Reference Measuring System for use in high-voltage impulse
testing are clearly laid out in IEC Publication 60-2:1994. Reference dividers
meeting these requirements are available from several manufacturers or can
be constructed by the user.