Abstract: An electrical apparatus includes an electrical device that generates heat and a fan unit. A case of the electrical device includes a first opening and a second opening. A case of the fan unit includes a third opening and a fourth opening. The case of the electrical device and the case of the fan unit are configured such that a space sandwiched between a recess of the case of the electrical device and the support rail and a space sandwiched between a recess of the case of the fan unit and the support rail constitute an air flow path.

Abstract: An electrical apparatus includes an electrical device that generates heat and a fan unit. A case of the electrical device includes a first opening and a second opening. A case of the fan unit includes a third opening and a fourth opening. The case of the electrical device and the case of the fan unit are configured such that a space sandwiched between a recess of the case of the electrical device and the support rail and a space sandwiched between a recess of the case of the fan unit and the support rail constitute an air flow path.

Abstract: A controller of a rotary switch receives, via a contact receiver, signals from a plurality of fixed contacts of a rotary switch that rotates a movable contact to connect the movable contact to any of the fixed contacts, and outputs a command based on the received signals. The controller of the rotary switch monitors a transition of an output code received from the contact receiver, and determines that a failure has occurred in the rotary switch when the transition of the output code does not match a transition pattern of the output code of the case where the rotary switch operates normally.

Abstract: A controller of a rotary switch receives, via a contact receiver, signals from a plurality of fixed contacts of a rotary switch that rotates a movable contact to connect the movable contact to any of the fixed contacts, and outputs a command based on the received signals. The controller of the rotary switch monitors a transition of an output code received from the contact receiver, and determines that a failure has occurred in the rotary switch when the transition of the output code does not match a transition pattern of the output code of the case where the rotary switch operates normally.

Abstract: A motor load switching system in which a single motor with a single control circuit drives a plurality of different-sized loads by sequentially switching from one load to another. A parameter storage device stores a plurality of parameter sets which are optimized for respective loads. In response to a load switching command, motor control device selects a corresponding parameter set from the parameter storage device and controls the motor according to the selected parameter set. Simultaneously, a load switching device couples the motor with a new load selected from the plurality of the loads.

Abstract: A motor drive method designed to eliminate the effect of variation of main voltage in the current control based on the PWM control. A main voltage detecting circuit detects a main voltage Vlink, and a main voltage equivalent value Vlink1 is set to be equal to this detected main voltage Vlink. Each of deviations between phase current commands Icu, Icv and Icw and phase currents iu, iv and iw detected is multiplied by the proportional gain K. Each product is then divided by the main voltage equivalent value Vlink1 to obtain respective phase duty ratios .eta.u, .eta.v and .eta.w of the PWM signal. The PWM signals with these duty ratios are outputted to an electric power converter to turn on or off the control switching elements for the drive control of the motor. The main voltage equivalent value Vlink1 is set to the detected main voltage Vlink to become equal to the actual main voltage, so that it becomes possible to calculate the duty ratio of the PWM signal which corresponds to the actual main voltage.

Abstract: A variable-reluctance motor is driven by means of a driver circuit which is composed of a common switching device and switching devices corresponding to individual phases. The sum (total current i.sub.t) of currents flowing through coils for the individual phases is detected. The duty ratio of a PWM signal for turning on and off the common switching device is computed in accordance with the deviation between the total current i.sub.t and a current command i.sub.cmd and the sign (positive or negative) of the deviation. Also, the on-off operation of the switching device corresponding to each phase is controlled depending on the excitation phase based on the rotor electrical angle and on whether the sign of the deviation is positive or negative. In this manner, current loop control is executed so that the detected total current i.sub.t follows up the current command i.sub.cmd.