Abstract: A method and apparatus for stopping an AC motor that is controlling a load while detecting mechanical brake slippage of a mechanical brake for holding the load against movement includes a controller for decreasing torque-producing current commands from the drive while a speed regulator is commanding zero speed, sensing movement of the load while the speed regulator is commanding zero speed, detecting movement of the load past a pre-determined distance limit, and increasing torque to support the load and prevent further movement of the load. The controller will again decrease torque-producing current commands from the drive, and again checking for movement of the load, and upon sensing no load movement upon reaching zero torque, then shutting off the motor.

Abstract: An elongate resistive sensor useful as an element of a pneumatic manifold failure detecting and locating system. A sensing loop is based on a coaxial cable having a core of known resistance per unit length. A eutectic salt impregnated insulant separates the core and sheath but has a temperature breakdown characteristic which provides the sensing function. Upon a pneumatic manifold failure, the sensing cable is heated, the eutectic salt insulator breaks down, a core-to-sheath short occurs, and currents in the sensing cable are substantially altered as a result. The cable is connected as a loop, and differential currents into the ends of the loop are detected and processed to determine the position of the short. Terminating resistors are associated with connectors which connect multiple cable sections into a single loop, and the terminating impedance is further sensed to determine an open circuit condition at any connector.