Abstract: An apparatus for measuring the winding temperature of electric machines uses an a.c. reference voltage source generating an a.c. reference voltage with a predetermined, non-line frequency, preferably below 10 Hz., a current detector detecting the current generated from the a.c. reference voltage and/or the a.c. reference voltage directly, and a measuring and evaluating device measuring the current to determine the winding temperature. The a.c. reference voltage is added geometrically to the line voltage and generates a current proportional to the winding conductance which is temperature dependent.

Abstract: An arrangement for measuring the slip of electric induction motors determines the relative measure of the difference between rotary field speed and rotor speed of induction motors by utilizing the nonlinearity effects of the magnetization characteristics of ferromagnetic materials. Slip-proportional current and/or voltage signals are detected at the terminals of the induction motor. By suitable processing of these slip-proportional signals, such as frequency conversion and filtering, a frequency-proportional measure of the slip is provided which is then subjectable to measuring or further processing.

Abstract: The minimum distance between a passing projectile and a training (dummy) target is ascertained by means of four shock wave responsive transducers in the target, two of which are aligned with the target's propagation and the transit time differential of receiving the shock wave from the projectile as well as measured distances to the projectile's trajectory are used to establish a set of possible projectile trajectories, one of them being the real one; all of them being arranged in rotational symmetry to the line established by the two transducers. This information suffices already to determine the minimum distance of fly by.