Kabushiki Kaisha Toshiba

Hiroshi Saito

Tetsuo Matsushima

Hidenari Amo

Yasuhiro Kurosawa

A digital distance relay for deciding whether a fault point is within a stipulated operation region by obtaining an impedance to the fault point. The relay comprises: means for deciding whether the impedance is within a specified region by applying a value proportional to the relative phase; and means for deciding the fault point is within the stipulated operation region if: (a) when the load current indicates a sending direction, the positive-phase resistance and reactance are within a stipulated region based on stipulated positive-phase resistance and reactance, and the impedance is decided within the specified region; or (b) when the load current indicates a receiving direction, the positive-phase resistance and reactance are within a stipulated region based on stipulated positive-phase resistance and reactance, or the impedance is decided within the specified region.

Digital distance relay

In an enlarged trend graph displaying method, a portion of an overall trend graph is enlarged so as to be displayed on a display screen subdivided into upper and lower reduced display sections and a middle enlarged display section. This enlarged trend graph displaying method comprises the steps of: calculating both a display area ratio of the middle enlarged display section to an overall display area of the screen for displaying the overall trend graph, and an enlargement ratio thereof, and also for calculating a reduction ratio of each of the upper and lower reduced display sections based upon the display area ratio and enlargement ratio of the middle enlarged display section; setting first data on the overall trend graph which has been enlarged by the enlargement ratio as a first virtual screen image indicative of the middle enlarged display section; setting second and third data on upper and lower portions of the overall trend graph which each has been reduced by the same reduction ratio as second and third virtual screen images representative of the upper and lower reduced display sections; scrolling a display position designating window for the first virtual screen image indicative of the middle enlarged display section, and simultaneously moving a viewport for the enlarged display section within the display screen in conjunction with the scrolling operation, whereby the overall trend graph is displayed on the display screen subdivided into the upper and lower reduced display sections and middle enlarged display section, and also the middle enlarged display section is moved within the display screen and displayed with having top priority with respect to displays for the upper and lower reduced display sections.

Growing community of inventors

Saitama-ken, Japan

Hiroshi Saito