The relevant behaviour of a high-power circuit-breaker with respect to its ability to interrupt short-circuit current is mainly restricted to a short time window of a few tens of microsecond. The objectives of the programme are the following:
* Development of a three-channel 40 MHz 12 bit resolution data-acquisition system for application in high-power laboratories
* Extraction of relevant circuit-breaker arc parameters
* Inclusion of arc models in suitable arc-circuit interaction computer software
* Comparison of existing standards with the predicted interruption performance in various circuits and with various circuit-breaker technologies.
State of progress
A new digital current-zero measuring system (having a sampling frequency of 40 MHz and a resolution of 12 bit) was used to monitor zero crossings of short-line fault currents in several designs of commercial high-voltage circuit breakers. The breakers were subjected to standard IEC 60056 short-line fault tests in a high power laboratory.
From the database of test results, new empirical arc models are derived, eg based on the series connection of classical modified Mayr models.
With the aid of such models, the influence of the (test-)circuit on the interrupting performance of circuit breakers can be evaluated, taking into account the individual characteristics of the breaker. Apart from this aspect, more direct evidence on the performance of breakers in IEC 60056 short-line fault tests can be gathered through evaluation of the arc resistance at current zero, or very close (few hundred ns) before current zero. Recently, high-power test were performed, in which this arc resistance (and the time dependent course of its limiting value) was used to compare the performance of two circuit breakers of the same rating but different manufacturer.
In high-power laboratories high-voltage circuit-breakers needed for the supply of electrical energy are tested in order to verify their correct functioning. Due to the large power involved and the physical size of this equipment, the testing is very expensive and time consuming. In order to make testing more efficient, in this programme, new methods of "digital testing" are developed. With these methods detailed test results obtained in convential "analogue" tests with specialised digital data acquision systems will be used to assess the behaviour of the equipment in other circumstances than those present during the real tests. With the aid of this method, standards can be verified and extended.
* KEMA Nederland BV: Development of hard- and software of a high-frequency high-resolution measuring system. Performance and evaluation of high-power testing.
* RWE Energie AG: Put at the disposal of test-objects and perform analysis results..
* Siemens AG: Further development of arc models for the design of circuit-breakers.
* Laborelec cv: Measurement in order to verify the correct functioning of the system.
* Delft University: Analysis of measurements, automatic parameter extraction and arc model integration in arc-circuit interaction software.
Funding SchemeCSC - Cost-sharing contracts
2628 CD Delft