An estimating method includes the following steps. Firstly, if the electrical machine control system is in the generator mode, a bus voltage of the bus capacitor is monitored continuously. Then, if the switch is turned to an on state, a first current value of a current flowing through the bus capacitor during an off state of the switch is calculated. Then, the switch is turned to the on state. Then, if the switch is turned to the off state, a second current value of a current flowing through the bus capacitor during the on state of the switch is calculated, and a resistance value of the braking resistor is estimated according to the first current value and the second current value.

An estimating method includes the following steps. Firstly, if the electrical machine control system is in the generator mode, a bus voltage of the bus capacitor is monitored continuously. Then, if the switch is turned to an on state, a first current value of a current flowing through the bus capacitor during an off state of the switch is calculated. Then, the switch is turned to the on state. Then, if the switch is turned to the off state, a second current value of a current flowing through the bus capacitor during the on state of the switch is calculated, and a resistance value of the braking resistor is estimated according to the first current value and the second current value.

A method for determining an electrical resistance of an electrical supply lead of an electrical system. The system is connected to a first and a second electrically conductive supply lead, which are electrically conductively connected on the current-source side. The system is configured to electrically connect an electrical load of the system selectably to the first or to the second supply lead. The method includes: configuring an electrical connection between the first supply lead and the load; configuring an electrical interruption between the second supply lead and electrical loads of the system; impressing a current in the first supply lead; determining a first voltage at the input of the first supply lead; determining a second voltage at the input of the second supply lead; determining a first resistance value of the first supply lead using the first and the second voltage and the impressed current.

A method for determining an electrical resistance of an electrical supply lead of an electrical system. The system is connected to a first and a second electrically conductive supply lead, which are electrically conductively connected on the current-source side. The system is configured to electrically connect an electrical load of the system selectably to the first or to the second supply lead. The method includes: configuring an electrical connection between the first supply lead and the load; configuring an electrical interruption between the second supply lead and electrical loads of the system; impressing a current in the first supply lead; determining a first voltage at the input of the first supply lead; determining a second voltage at the input of the second supply lead; determining a first resistance value of the first supply lead using the first and the second voltage and the impressed current.

There is provided a method for determining a quality of an abrasive surface preparation of a composite surface, prior to the composite surface undergoing a post-processing operation. The method includes fabricating levels of abrasive surface preparation standards for a reference composite surface; using a surface analysis tool in the form of an ohm meter, to create target values for quantifying the levels; and measuring, with the surface analysis tool, one or more abrasive surface preparation locations on the composite surface of a test composite structure, to measure one or more of, electrical resistance and surface resistivity, of the composite surface, to obtain test result measurement(s). The method further includes comparing the test result measurement(s) to the levels, to obtain test result level(s); determining if the test result level(s) meet the target value(s); and determining whether the composite surface is acceptable to proceed with the post-processing operation.

There is provided a method for determining a quality of an abrasive surface preparation of a composite surface, prior to the composite surface undergoing a post-processing operation. The method includes fabricating levels of abrasive surface preparation standards for a reference composite surface; using a surface analysis tool in the form of an ohm meter, to create target values for quantifying the levels; and measuring, with the surface analysis tool, one or more abrasive surface preparation locations on the composite surface of a test composite structure, to measure one or more of, electrical resistance and surface resistivity, of the composite surface, to obtain test result measurement(s). The method further includes comparing the test result measurement(s) to the levels, to obtain test result level(s); determining if the test result level(s) meet the target value(s); and determining whether the composite surface is acceptable to proceed with the post-processing operation.

The invention relates to a circuit arrangement (12) for monitoring and triggering an igniter (5) of an active electrical fuse (6). The arrangement comprises: a control and evaluation unit (1), an alternating current generating unit (2) activated by the control and evaluation unit (1), an alternating current transmission unit arranged between the igniter (5) and the alternating current generating unit (2), the control and evaluation unit (1) being designed and programmed, in a first operational state, to determine the electrical resistance of the igniter (5) from a current detected on the primary side and a voltage detected on the primary side, the value of the resistance being a measure for tripping of the igniter (5), and, in a second operational state, to trigger the igniter (5) by means of the alternating current generating unit (2). The invention further relates to an associated method, to a computer program product which carries out the method and a computer-readable medium, and to a converter and to an aircraft having such a circuit arrangement.

The invention relates to a circuit arrangement (12) for monitoring and triggering an igniter (5) of an active electrical fuse (6). The arrangement comprises: a control and evaluation unit (1), an alternating current generating unit (2) activated by the control and evaluation unit (1), an alternating current transmission unit arranged between the igniter (5) and the alternating current generating unit (2), the control and evaluation unit (1) being designed and programmed, in a first operational state, to determine the electrical resistance of the igniter (5) from a current detected on the primary side and a voltage detected on the primary side, the value of the resistance being a measure for tripping of the igniter (5), and, in a second operational state, to trigger the igniter (5) by means of the alternating current generating unit (2). The invention further relates to an associated method, to a computer program product which carries out the method and a computer-readable medium, and to a converter and to an aircraft having such a circuit arrangement.

A circuit for determining and/or compensating for a measurement error of a sheathed sensor due to a property of a sheath of that sheathed sensor comprises a first and a second terminal for connecting to a pair of sensor signal leads of a sensor element in a sheathed sensor and a voltage measurement circuit. A switching unit controls switching an electrical connection between a first and a second state. A correction measurement circuit generates a correction signal indicative of that a measured current running from the first terminal through the switching unit. A controller receives the measurement and correction signal in both the first and second state, and calculates an error value indicative of the measurement error and/or a sensor readout value that is corrected for the measurement error by taking the measurement and correction signal into account as obtained in both the first and second state.

A circuit for determining and/or compensating for a measurement error of a sheathed sensor due to a property of a sheath of that sheathed sensor comprises a first and a second terminal for connecting to a pair of sensor signal leads of a sensor element in a sheathed sensor and a voltage measurement circuit. A switching unit controls switching an electrical connection between a first and a second state. A correction measurement circuit generates a correction signal indicative of that a measured current running from the first terminal through the switching unit. A controller receives the measurement and correction signal in both the first and second state, and calculates an error value indicative of the measurement error and/or a sensor readout value that is corrected for the measurement error by taking the measurement and correction signal into account as obtained in both the first and second state.