Abstract: Protection of an electrical generator includes determining a rotor and stator components using rotor and stator electrical signals, calculating a unbalance and/or differential component using the stator and rotor components, and determining a stator or rotor fault based on the unbalance and/or differential component. Further, the faulted phase and/or zone of a stator fault may be determined using the stator positive sequence voltage and negative sequence current.

Abstract: A comminuting machine includes a frame, a comminuting rotor coupled to the frame, and a rotary drive coupled to the rotor. The rotary drive including a controller, a multi-phase motor connected to the controller, a set of contactors disposed between the controller and the multi-phase motor for selectively providing driving motive force to the multi-phase motor, and at least one rheostat disposed between the controller and the multi-phase motor, in parallel with the first set of contactors, for selectively providing a stopping resistance to the multi-phase motor to effect frictionless braking of the comminuting rotor, wherein the controller is configured to operate the set of contactors and the at least one rheostat to single phase lines of the multi-phase motor for providing the stopping resistance.

Abstract: A braking apparatus is provided for braking the rotating part of a hoisting machine. The braking apparatus includes one or more brakes, which contain altogether at least one movable brake shoe, spring elements for activating the brake by moving the brake shoe forward, at least two electromagnets, which, when magnetized by a magnetizing current, apply a force of attraction to bodies conducting magnetic flux. The electromagnets are fitted to release the brake by pulling the brake shoe backwards by resisting the spring elements. The brake is fitted to be activated by reducing the magnetizing current of the electromagnet. The braking apparatus includes a power supply circuit for the electromagnets, which contains controllable power supply interrupting devices. The electromagnets are connected to the power supply circuit in such a way that the supply of magnetizing current to each electromagnet can be interrupted by means of at least two different interrupting devices.

Abstract: A driving control circuit of a hood motor, including: a hood motor section rotatably driven for ventilating the inner portion of a system; a rectifier circuit section for supplying direct current power to the hood motor by rectifying alternating current power, a controlling section for generating a control signal for controlling the operation of the hood motor; and a driving circuit section for controlling the operation of the hood motor according to the control signal from the controlling section.

Abstract: A variable speed control is provided for controlling a reversing permanent split capacitor motor in an automatic washer. The operation of the motor is controlled such that the motor will accelerate for a first predetermined time period and then coast with no power applied for a second predetermined time period. This generalized operation of the motor occurs in the spin cycle. In the agitate cycle, a logic decoding circuit uses a tach pulse signal indicative of the speed of the motor to provide a time for the motor to be on, and utilizes an AC line current zero crossing signal from a zero crossing detector to establish a time during which the motor is off, the motor on plus off time establishing a stroke rate for the agitate cycle.

Abstract: This invention relates to a motor controller which is so arranged that voltage to be applied to drive windings of a synchronous motor (1) is switched by a plurality of switching elements of a power inverter circuit (4), while the current supply amount to the switching elements is controlled based on pulse width-modulated signals, and which is provided, at a distributing section for selecting energization of said switching elements, with a first logic circuit for applying the pulse width modulation only to the predetermined switching selected from among the switching elements selected during forward rotation of the motor, and a second logic circuit for applying the pulse width modulation to all of the switching elements selected during the reverse rotation of the motor, so as to thereby effect the reduction of electro-magnetic noise during the forward rotation, and to effect the suppression of current during the reverse rotation.

Abstract: An electrical switching circuit for a multi-phase a.c. supply uses semiconductor rectifier switches SCR1 to 5 to reversibly switch power to a multi-phase electric motor so that the motor can be run in a forward or a reverse direction. The SCRs are provided in two sets, one for switching power to forward run the motor, and the other set for reverse running of the motor. Inductor elements .DELTA.L are connected in series with the SCRs. The inductor elements comprise coils which include a non-linear permeability core, for example of ferrite or permalloy, which are operative to suppress voltage transients at switch on of the motor. These transients would otherwise produce spurious firing of the SCRs and could produce a short circuit across the input phases of the a.c. supply. The circuit is used in a valve actuator. Improved torque limit switches and position limit switches are disclosed, which operate a low voltage and which use Reed and Hall effect switches.