Patent Document ID: 9263862
Application ID: 14304591
Patent Flag: 1

Claim One:
1. A method for operating a fluid-insulated electrical apparatus wherein an insulation fluid of the electrical apparatus comprises at least a first component and a second component, the method comprising the method elements of: determining a physical state of the insulation fluid by measuring at least three measurement variables by means of at least one sensor, wherein the measurement variables are indicative of the physical state of the insulation fluid and wherein the measurement variables are selected such that at least two characterizing variables indicative of partial pressures (p A , p B ) or concentrations (c A , c B ) of the first component and the second component of the insulation fluid can be determined using the measurement variables, wherein the method comprises a further method element of: deriving at least one trend variable for at least one of the measurement variables, wherein the at least one trend variable is indicative of a change over time of the at least one measurement variable; and/or a further method element of: deriving from at least one of the measurement variables at least one of the characterizing variables, wherein the at least one of the characterizing variables is indicative of the physical state of the insulation fluid, and deriving at least one trend variable for the at least one of the characterizing variables, wherein the trend variable is indicative of a change over time of the at least one of the characterizing variables; wherein at least two trend variables are derived for the at least two characterizing variables indicative of the partial pressures (p A , p B ) or concentrations (c A , c B c B ) of the first and second components of the insulation fluid, and wherein the at least two characterizing variables are selected from the group consisting of: a function f 1 (p A ), a function f 2 (p A /T), a function f 3 (p B ), a function f 4 (p B /T), a function f 5 (p A , p B ), a function f 6 (p A , p B , T), a function f 7 (p A /p B ), a function f 8 (c A ), a function f 9 (c B ), a function f 10 (c A , c B ), and a function f 11 (c A /c B ), with p A and p B being the partial pressures of the first and second components of the insulation fluid, with c A and c B being the concentrations of the first and second components of the insulation fluid, and with T being a temperature T of the insulation fluid; wherein further the method comprises a method element of: determining, using the at least one trend variable for the at least one of the characterizing variables, an operating state of the electrical apparatus out of a group of at least two possible operating states, wherein a first possible operating state of the electrical apparatus corresponds to a first fault scenario for the electrical apparatus and a second possible operating state of the electrical apparatus corresponds to a second fault scenario for the electrical apparatus; and wherein at least one of the first and second fault scenarios for the electrical apparatus is selected from the group consisting of: uniform leakage of the insulation fluid, preferential leakage of the first or the second component of the insulation fluid, preferential condensation of the first or the second component of the insulation fluid, appearance of at least a third component in the insulation fluid, decomposition of at least the first or the second component of the insulation fluid, intermolecular reactions between molecules of the first and the second components of the insulation fluid, and removal of at least the first or the second component of the insulation fluid.