Abstract: A method of operation and apparatus is provided for performing a surge test of electrical insulation of at least part of a winding under test, the winding being a winding of an electrical machine. The apparatus comprises a test device having a surge generator, at least two test connections for connecting to the test device, and a damping device comprising a resistance. The damping device is connected across the part of the winding under test, the test connections are arranged to connect a parallel combination of the damping device and the part of the winding under test to the test device and a voltage impulse is generated using the surge generator.

Abstract: A meter performs measurements of imbalance of an electrical characteristic between conduction paths of an electrical machine having a plurality of stator windings and a rotor, with the rotor in place in the electrical machine. For each of a plurality of conduction paths, each comprising one or more of the plurality of stator windings, the meter provides a test current to the conduction path and performs a measurement A of an electrical parameter of the conduction path in a time window A starting after a delay period from the start of providing the test current and determines a measure of imbalance of the electrical characteristic between the plurality of conduction paths from at least the measurements A of the electrical parameter for the respective conduction paths.

Abstract: A method of operation and apparatus is provided for performing a surge test of electrical insulation of at least part of a winding under test, the winding being a winding of an electrical machine. The apparatus comprises a test device having a surge generator, at least two test connections for connecting to the test device, and a damping device comprising a resistance. The damping device is connected across the part of the winding under test, the test connections are arranged to connect a parallel combination of the damping device and the part of the winding under test to the test device and a voltage impulse is generated using the surge generator.

Abstract: A method and apparatus for directing a coolant stream for use with a computer numerically controlled (CNC) machine tool includes a nozzle pivotably mounted on a machine tool. The position of the nozzle is automatically adjusted using information available in the CNC machine control program and the part program (i.e. G-Code) to determine where to direct the coolant nozzle at each instant in time. Integration with the machine control program allows the coolant delivery system to be continuously adaptive to machine position. The position of the coolant delivery system is computed by algorithms according to a user selected strategy. The strategy is specified within the control language of the machine control program (i.e. G-Code). No operator programming outside of using G-Code commands to select the desired operating mode is required to direct the coolant nozzle. The user can change operating modes while the machine is running by issuing G-Code commands.