Abstract: A switching device including a measuring means for monitoring contact erosion, which is provided between a contact element and an associated contact support. The switching device includes an electrically insulated signal line, which is usable in individual and/or multiple contacts, is used as the measuring means, the signal line being integrated into a single monitoring circuit. In the switching device, there is arranged, between at least one of the contact elements and the associated contact support or in the contact material, an electrical conductor with insulator as the signal line, damage to or destruction of the insulator and/or the conductor being utilized to generate an external signal as an indication of the end of the service life of the contact element.

Abstract: An nth order magnetic multipole arrangement for influencing the trajectory of charged particles is disclosed. In order to avoid using structural parts that are manufactured separately, it has been found to provide as the multipole arrangement, the stator of a multi-pole alternating current machine, the stator winding of which is fed by a voltage source in such a way that the produce of current and number of turns (number of ampere turns) in a groove or group of grooves disposed under the azimuth angle .theta. is proportional to cos (n .theta.), n corresponding to the order (order number) of the multipole arrangement, and the factors a and b being taken from the ratio b/a which states the orientation of the multipole relative to the azmith angle .theta.=0. As the multipole arrangement there may be provided also a stator, excited by permanent magnets, of a direct current machine.

Abstract: An apparatus and method for increasing the maximum speed of rotation of a synchronous machine having constant excitation field strength is disclosed. The synchronous machine is preceded by a converter, which has an adjusted current reference value as an input. The adjusted current reference value comprises an active-current reference value and a reactive-current reference value. For actual speeds n.sub.ist, the absolute value .vertline.n.sub.ist .vertline. of which is above a predetermined value n.sub.o, the amplitude of the active-current reference value is limited to a value which is inversely proportional to the factor .vertline.n.sub.ist .vertline./n.sub.o. The value n.sub.o is a predetermined speed at which the sum of the magnet wheel voltage of the synchronous machine and the voltage drop in the stator winding is maximally equal to the largest possible output voltage of the converter. To obtain the adjusted current reference value, a reactive-current reference value shifted 90.degree.

Abstract: Arcuate permanent magnets are inserted into the bore hole of a stator intended for use in an electric machine which is excited by permanent magnets. Spring elements, inserted into recesses in the wall of the bore between the magnets, have spring arms which are connected to each other via a back part and which rest against axially extending lateral edges of the permanent magnets. To insure retention of the permanent magnets against high mechanical shock stresses without connecting the spring elements to the stator, the spring elements are provided with extensions, formed on their back parts, which frictionally engage undercuts in the recesses. The spring arms themselves extend around the lateral edges of the permanent magnets in a form-locking manner.