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Traceability and Mutual Recognition of Impulse Voltage Measurements

Objective

Objectives
The main objectives are to promote mutual recognition and acceptance of reference measuring systems and calibration certificates and to develop and establish a generally accepted impulse/DC conversion for high-voltage measurements. Additional and more detailed objectives are to set up the scientific basis for mutual acceptance of high impulse voltage measurements within member countries as well as with other European and Non-European countries. In addition, the objective is to further develop the impulse voltage measurement and comparison techniques and to address difficult situations like testing with and measurements of full and front-chopped impulses superimposed with noise, oscillations and overshoot.

State of progress
The progress of the work during the first period of six months was good. The Reference System was established and tested according to plans and even more. In some parts, the system is better than planned, e.g. impulse calibrators. The project homepage and related work by email appeared to be an effective way of communication. The circulating system is compact and a number of auxiliary equipment are circulated to improve the comparison measurements and to make them most effective. A comprehensive software for controlling the measurements and processing and saving the results is provided. The documentation is extensive and well beyond the original plans. The system was sent out for circulation in July 1999, two months before scheduled in the contract. However, some technical problems postponed the first comparison, and the circulation was re-started from USA after reparations and checks. Only three laboratories could complete their comparison measurements in 1999, because of considerable and unexpected problems in transports and customs declarations.

Intercomparison techniques of difficult high-voltage impulse measurements need further development and experience. Firstly, the problems observed in the latest intercomparisons are related to accuracy of front-time T1 of full impulse, measurements of amplitude and time parameters of front-chopped impulses and application of curve fitting (mean curve) in calibrations and intercomparisons. Secondly, work for establishment of impulse/DC conversion is needed for the basis of the traceability. High-voltage impulse measurements are based on DC, AC, impedance, step and time measurements with manifold and complicated traces to national and international standards. No generally accepted impulse/DC conversion exists. Thirdly, the mutual recognition of reference systems and calibration certificates shall be supported and proceeded by all means in the member states and in important export countries.

Objectives
The main objectives of the project are the following:
- To further develop the impulse voltage measurement and intercomparison techniques and to address difficult situations like testing with and measurements of full and front-chopped impulses superimposed with noise, oscillations and overshoot;
- To develop and establish a generally accepted impulse/DC conversion for high voltage measurements;
- To set up the scientific basis for mutual acceptance of impulse voltage measurements within member countries as well as between member countries and other European countries and USA, Canada, Australia, India, Japan, Korea, Argentina and Brazil;
- To proceed with mutual recognition and acceptance of reference measuring systems and calibration certificates.

Work programme
The work programme consists in performing intercomparison measurements at 1 kV level and at 400 kV level and in circulating a full 400 kV impulse voltage measuring system with digitiser and impulse calibrator by 24 participating laboratories. This intercomparison includes two new features: impulse calibration of the used digitisers and impulse calibration of the full measuring system.

State of progress
Some equipment has been ordered and received. The preparation of the measuring system for circulation is in progress.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Helsinki University of Technology
Address

02015 Espoo
Finland

Participants (1)

UNIVERSITA DEGLI STUDI DI PADOVA
Italy
Address
Via Gradenigo 6 A
35131 Padova