Abstract: A circuit for automatically disconnecting a shaft drive spinning a textile winding bobbin and automatically substituting a circumferential cylinder drive for the shaft drive is disclosed. The cylinder drive becomes effective a short time after the start of the textile winding process. A signal proportional to the torque of the shaft drive motor is stored in a storage amplifier shortly after the start of the winding process. If the continuously measured instantaneous current value of the shaft drive exceeds, when both drives operate in parallel, the stored current value, a command to switch off the shaft drive is given.

Abstract: An electric group drive having synchronous motors which are fed from a static operating converter has a second converter for use in varying the relative angle position of the motors. Provision is made for using the second converter as a start-up and braking converter. A phase shifter and memory-oriented control logic are used to control the processes.

Abstract: An arrangement for bridging brief network failures in intermediate-link converters converts the kinetic energy in load motors into electrical energy by reducing the frequency of the converter. Such a frequency reduction is performed in accordance with the value of a control deviation signal corresponding to the difference between desired and actual frequencies of operation of the converter. The control deviation signal is produced by the combination of a PI controller which is coupled at its output to an integrator circuit. The integrator circuit controls the frequency and voltage of the converter.

Abstract: An apparatus for changing the relative angles of the output shafts of a multiple-motor electric drive. For this purpose, the appropriate synchronous motor is switched to a phase-shifting frequency changer and its relative shaft (mechanical phase) angle is shifted by varying the frequency. The synchronous motor is then switched back to the operating frequency changer. The phase equality of the output voltages of the two frequency changers is monitored by signals derived from logic elements driving the frequency changers. In normal operation, the phase shifting frequency changer is driven by the same digital frequency generator as the operating frequency changer and is only switched to another frequency generator for phase shifting. Transition from one frequency changer to the other is made without shock.