US 11,982,703 B2
Method for monitoring a protective device that includes a series circuit of thyristors connected in parallel with an electrical device to be protected
Nils Stahlhut, Roettenbach (DE)
Assigned to Siemens Energy Global GmbH & Co. KG, Munich (DE)
Filed by Siemens Energy Global GmbH & Co. KG, Munich (DE)
Filed on Jul. 18, 2022, as Appl. No. 17/866,729.
Claims priority of application No. 21185964 (EP), filed on Jul. 16, 2021.
Prior Publication US 2023/0017873 A1, Jan. 19, 2023
Int. Cl. G01R 31/26 (2020.01); H02H 3/20 (2006.01)
CPC G01R 31/263 (2013.01) [H02H 3/20 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A method for monitoring a protective device, the protective device having a series circuit of N>1 thyristors connected in parallel with an electrical device to be protected, and a snubber branch connected in parallel with each thyristor, the method which comprises:
firing a number n<N thyristors in a first thyristor group when:
a positive voltage is present across the series circuit of thyristors; and
a negative snubber current is flowing through the snubber branches of the thyristors in the first thyristor group;
detecting a switching-on or non-switching-on of at least one of the thyristors of the n<N thyristors in the first thyristor group in response to the firing; and
establishing a malfunction of at least one thyristor if non-switching-on of at least one of the thyristors was detected.