Protecting Electrical Equipment by Vladimir Gurevich

Author:Vladimir Gurevich
Language: eng
Format: epub
Publisher: De Gruyter
Published: 2021-02-22T10:27:12.316000+00:00

9.2

Analysis of the literature

There are several publications that study sources of high-frequency electromagnetic pulses at power industry facilities and their influence on a DPR [2], [3], [4], [5], [6]. It should be noted that these publications discuss Japanese DPRs and the issues of the power industry in Japan. I could not find any information regarding European DPRs. Moreover, regardless of my personal extensive work experience in the power industry, I did not come across any significant issues with DPR protection during operation of high-voltage switching equipment in gas-insulated substations.

It is weird to read that the use of such simple tools, such as ferrite filters on control cables and additional absorbing capacitors on input terminals of a DPR and the printed circuit board of a CPU [3], solved the problem of DPR’s resistance to this kind of electromagnetic impact. One can assume that a Japanese DPR does not have any electromagnetic filters and circuits that suppress noise. Another strange thing is that Japan adopted a new standard of test pulses for a DPR, where the amplitude of high-frequency test pulses was reduced from 4 kV [7] to 1 kV [8], with simultaneous modification of their shape. Thus, the standard stipulates that test pulses should be rectangular and should have a rise time of 1 ns and a pulse width of 100 ns (1/100 ns), instead of a so-called quick nanosecond pulse featuring 5/50 ns according to [7]. Some publications of Japanese authors suggest that adoption of this standard has improved noise resistance of Japanese DPRs. At the same time, they do not address the issue of the source of these pulses: In other words, they do not mention the necessity to build special testing equipment and use it instead of available tools for standard tests. In addition to that, there are no data about comparison tests of DPRs and their responses to standard (5/50 ns) pulses and 1/100 ns pulses offered by Japan author. Without these comparison tests, the use of the Japanese standard for testing low-amplitude (four times lower) pulses and the insignificant differences in terms of speed of rise and length is questionable. This is especially true because in real conditions the noise signal arrives at the DPR’s input terminals via rather long cables, featuring apparent inductance for nanosecond pulses and thus largely affecting their shape. Thus, a 1/100 ns pulse is unlikely to differ from a 5/50 ns pulse at the DPR’s input terminal.

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