US 12,217,922 B2
Method for monitoring vacuum interrupter's condition and an electric switching device
Lukasz Bachorz, Mount Martha (AU); and Timothy John Heemskerk, Mooroolbark (AU)
Assigned to HITACHI ENERGY LTD, Zurich (CH)
Appl. No. 17/802,115
Filed by Hitachi Energy Ltd, Zürich (CH)
PCT Filed Feb. 24, 2020, PCT No. PCT/EP2020/054781
§ 371(c)(1), (2) Date Aug. 24, 2022,
PCT Pub. No. WO2021/170208, PCT Pub. Date Sep. 2, 2021.
Prior Publication US 2023/0086911 A1, Mar. 23, 2023
Int. Cl. H01H 33/668 (2006.01); G01R 31/327 (2006.01)
CPC H01H 33/668 (2013.01) [G01R 31/3275 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method for monitoring a condition of a vacuum interrupter of an electric device, comprising:
receiving a first voltage signal indicating a first voltage between a source line and a first contact of a switch inside the electric device, the first contact of the switch coupled to the source line;
receiving a second voltage signal indicating a second voltage between a second contact of the switch and a reactive component, the second contact of the switch coupled to the reactive component;
receiving a current signal indicating a current at the second contact of the switch;
determining an occurrence of a restrike in response to determining a simultaneous increase in amplitudes of the first voltage signal, the second voltage signal, and the current signal; and
determining the condition of the vacuum interrupter based on the determined occurrence of the restrike, wherein determining the condition of the vacuum interrupter based on the determined occurrence of the restrike comprises either
counting a number of switching operations, between open and closed, performed by the switch in a time period, counting a number of determined occurrences of the restrike in the time period, computing a ratio of the counted number of the determined occurrences of the restrike to the counted number of the switching operation, and determining an unacceptable vacuum condition in response to determining that the computed ratio exceeds a predetermined ratio value, or
in response to determining the restrike, counting a number of switching operations, between open and closed, that are performed by the switch in a time period between the restrike and a subsequent determined restrike, and determining an unacceptable vacuum interrupter's condition in response to the number of the switching operations being below a predetermined number.