Method for monitoring a protective device that includes a series circuit of thyristors connected in parallel with an electrical device to be protected
AssigneeSiemens Energy Global GmbH & Co. KG
InventorNils Stahlhut
Life of this patent
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Abstract
A method for monitoring a protective device, which has a series circuit of a multiplicity of thyristors. The protective device has a series circuit of N>1 thyristors. The series circuit is connected in a parallel circuit with an electrical device to be protected. A snubber branch is connected in parallel with each thyristor. For the purpose of testing a firing capacity, n<N thyristors in a first thyristor group are fired when a positive voltage is present across the series circuit and a negative snubber current is flowing through the snubber branches of the thyristors in the first thyristor group.
Claims12
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.
Dependencies are inferred from the claim text.