AS IEC 60060.2:2018 pdf download – High-voltage test techniques Part 2: Measuring systems.
4.2 Schedule of performance tests
To maintain the quality of a measuring system, its assigned scale factor(s) shall be determined by periodic performance tests, The interval between performance tests shall be based on evaluation of past stability of the measuring system. It is recommended that the performance test should be repeated annually, but the maximum interval shall not be longer than five years.
NOTE Long intervals between performance tests can increase the risk of an undetected change in the measurement system.
Performance test shall be made after major repairs to the measuring system and whenever a circuit arrangement that is beyond the limits given in the record of performance is to be used.
When a performance test is required because a performance check shows that the assigned scale factor is no longer valid, the cause of this change shall be investigated before the performance test is made.
4.3 Schedule of performance checks
Performance checks shall be made at intervals based on the recorded stability of the measuring system as shown in the record of performance. The interval from the last performance test or the last performance check shall not be longer than one year.
For a new or repaired measuring system, performance checks shall be made at short intervals to demonstrate its stability.
No reference method is identified for the performance checks because the required accuracy is less than that required for performance tests.
4.4 Requirements for the record of performance
4.4.1 Contents of the record of performance
The results of all tests and checks, including the conditions under which the results were obtained, shall be kept in the record of performance (stored in paper format or electronically if permitted by quality systems and local laws) established and maintained by the user. The record of performance shall uniquely identify the components of the measuring system and shall be structured so that performance of the measuring system can be traced over time.
The record of performance shall comprise at least the following information:
• General description of the measuring system.
• Results of type and routine tests on the converting device, transmission system(s) and measuring instrument(s) and, if performed, on the measuring system.
• Results of subsequent performance tests on the measuring system.
• Results of subsequent performance checks on the measuring system.
NOTE The general description of the measuring system usually comprises main data and capabilities of the measuring system, such as the rated operating vo4iage, waveform(s), range(s) of clearances, operating time, or maximum rate of voltage applications. For many measuring systems, information on the transmission system as well as high-voltage and ground-return arrangements are important.
4.4.2 Exceptions
For measuring systems or components manufactured before the date of issue of the second edition of 1EC60060-2, i.e. 1994, the required evidence may not be available for some part(s) of the type and routine test. Then performance tests and checks made in accordance with earlier versions of this standard are deemed adequate provided they show the scale factor is stable. The results of these previous checks shall also be entered in the record of performance.
Approved measuring systems comprising several pieces of equipment used inter-changeably may be covered by a single record of performance including all the combinations possible with the least amount of duplication possible. Specifically, each converting device shall be covered individually, but transmission systems and measuring instruments may be covered generically.
4.5 Operating conditions
A measuring system shall be connected directly to the terminals of the test object, or in such
a way that the voltage difference between test object terminals and the measuring system is
negligible. The parasitic coupling between the test and measuring circuit should be minimized.
NOTE 1 Parasitic coupling may need to be investigated.
An approved measuring system shall have an uncertainty within the specifications of this standard throughout the ranges of operating and environmental conditions given in the record of performance.