Abstract: A user communicates travel destinations to a transportation system utilizing a human-machine interface having a touch screen with a selection of designations that can be individually selected by touching the screen. For example, a selected designation “Library” is communicated from the human-machine interface to a transportation system control without the user knowing where the library is actually located. The control determines the real locational parameter of the travel destination from a table storage device containing the designations and the associated real locational parameters. The control assigns the desired travel destination, such as a floor, to vehicle, such as an elevator car, with the best travel conditions and informs the user of the assigned vehicle on the touch screen. The information displayed to the user can include a vehicle identification, a travel destination identification, instructions and an indication of the place of boarding.

Abstract: An elevator drive has a traction sheave over which ropes are passed to move an elevator car and a counterweight up and down in an elevator hoistway. An elevator control in a control cabinet on a landing is connected with another elevator control in the hoistway and with the elevator car, and controls how the elevator car moves. The control cabinet also has a handle that is part of a Bowden cable acting on a brake of the elevator drive. The handle can be used to manually release the brake which permits the elevator car to move up or down depending on the difference in weight between the elevator car and the counterweight. The position of the elevator car in the hoistway is of significance to the elevator control. A tensioned toothed belt spanning the height of the hoistway is in contact with an encoder that detects the absolute position of the elevator car for the elevator control. For evacuation, a signal device is provided which allows evacuation of the car without looking into the elevator hoistway.

Abstract: A device for signaling the position of an elevator car in the case of passenger evacuation includes a measurement circuit connected to a landing door safety chain of the elevator installation. The measurement circuit has at least one LED that indicates to a rescuer person the presence of the elevator car at a floor.

Abstract: The auxiliary device is needed when the elevator stands in the elevator shaft outside a station. The auxiliary device includes an auxiliary drive device for the payload receptacle. For sight-free observation of the auxiliary device there is arranged an image transmission device, which includes a sensor, a display device and a transfer path. The sensor serves for detection of images which illustrate a drive pulley coupled with the auxiliary drive device. The display device serves for visualization of the images detected by the sensor, and the transfer path serves for transmission of the images detected by the sensor to the display device.

Abstract: A fastening system for lift shaft information transmitters includes multiple carriers to support shaft information transmitters in different height positions for each story upon cables stretched over the entire height of the shaft. A respective bracket arranged at a guide rail may be provided at each of the lower and upper shaft ends. Tension springs, which are connected at one end each with a respective shackle, are connected at cable thimbles of the lower cable ends. The cable can be prestressed by the shackle arranged at the lower bracket. In an illustrative embodiment, three cables are provided, wherein the middle cable is slightly displaced relative to the outer cables towards the rear in the depth of the shaft and the outer cables are slightly displaced inwardly in the width of the carrier. For larger lift installations, a retaining rail, which is arranged at the guide rail and by means of which the cables are held fast, may be provided for each three to four storys.

Abstract: For fastening a shaft magnet to a guide rail there is provided a holder with clip characteristics, which consists integrally of a foot part, a back part and a front part, at which a recess for reception of the shaft magnet is arranged. The foot part of the holder has a respective reinforcing rib at each side and a first chamfer at the free end. The front part with the recess has a second chamfer. The foot part and the front part in the rest state run slightly towards one another towards their free ends. On pushing of the holder onto the guide rail the foot part and the front part are lightly spread, whereby the holder is firmly clipped to the guide rail by the spring properties of the back part. The shaft magnet can now be placed on the guide rail through the recess. The shaft magnet is fully retained at the guide rail by its magnetic force.

Abstract: In accordance with an elevator system for controlling a response to a call of the present invention, each of sub-controllers includes a unit of storing the information regarding service ability to a hall call, and a unit of determining service ability based on the information stored in the unit when the call is generated from the hall, regardless of a call response signal from a main controller. As a result, the determination and display of service ability to the hall call can be rapidly exactly performed. In addition, the main controller includes a unit of checking and determining abnormality of the sub-controllers, and a unit of storing an identifier of the abnormal sub-controller. Since the data is not transmitted to the abnormal sub-controller, a data transmission amount may be decreased. Also, during the repair or replacement work of the abnormal sub-controller, an identifier thereof can be rapidly confirmed.

Abstract: The invention relates to a system and method for simultaneously displaying advertising and general news information in elevator cabs and waiting areas. The invention consists of a plurality of display monitors coupled to a plurality of servers. In operation, a first server receives a program schedule with associated advertising and general news information over a communication link from at least a second server. At predetermined times according to the program schedule, the first server transmits the advertising and general information to associated display monitors for viewing by passengers in the elevator cabs. The display monitors and associated servers are each individually addressable thus allowing them to be simultaneously updated from a remote location with new program schedules, news updates, customized advertising information and the like.

Abstract: A multi-segment display for the representation of alphanumeric characters, formed by uniting several character-display elements having multiple segments. The united display segment elements have common vertical segments. Greater freedom for representing the characters while requiring the smallest possible number of segments is obtained by such a construction. In addition, gaps between character representation can be minimized or eliminated, allowing characters to be represented in a centered arrangement with a regular spacing.

Abstract: A controller for an elevator. The elevator includes a landing passageway where a car stops and passengers board or alight and a hoistway through which the car is raised or lowered. A control panel for controlling the raising, lowering, and stopping of the car is disposed in the hoistway at a position where the control panel does not interfere with the raising or lowering of the car, and a mechanism for drawing out the control panel to the landing passageway is provided. Accordingly, space in the hoistway is effectively used, and the landing passageway which passengers do not use during maintenance can be readily utilized for a maintenance operation.

Abstract: The condition of the hoistway doors and the elevator door are continuously monitored. The opening of a hoistway door unaccompanied by opening of the car door being an indication of hoistway access; the car then is moveable only at inspection (slow) speed by utilizing controls on the car top; restoration to normal is achieved only by returning the inspection switch on the car top to normal operation while a hoistway door is open, and subsequently closing the hoistway doors and/or by activating a reset located outside the hoistway. Inspection speed limit switches are installed near the top and bottom of the hoistway positioned so that if operated while the elevator is traveling at inspection speed, the car will stop at a position which leaves a person ample room from the hoistway overhead or the pit floor. If a person enters the pit, normal operation is restored only by closing the hoistway door and subsequently engaging an external reset switch (outside the hoistway).

Abstract: The present invention prepares a rule base for storing therein a plurality of control rule sets, predicts a group management performance such as a waiting time distribution which is obtained when applying an arbitrary rule set stored in the rule base to the current traffic situation, and selects the optimal rule set in accordance with the performance prediction result. In addition, a weight database for storing therein weight parameters of a neural net corresponding to the rule sets and performance learning measure for correcting the weight parameters in the weight database in accordance with the learning result of the neural net is provided, whereby the prediction of the group management performance by the neural net using the corrected weight parameters is carried out.

Abstract: The next destination for an automatically registered elevator call is displayed to a passenger on a portable card that he carries, when he passes a beacon adjacent to the elevator, only if the destination is designated as “fixed”; if the destination is designated as “unfixed”, a new next destination is determined from a record of the passenger's destinations (which may include a history of the passenger's travel habits) and the floor upon which the beacon is situated. A transponder remote from the elevator entrance responds to a transmission from the card to register a hall call for that floor; a transponder in the car can sense a transmission from the card to enter a car call for the destination floor; if there is no car transponder, the destination is stored and a car call entered automatically upon the arrival of a car in response to the hall call. If the passenger enters a new destination, it is designated as “fixed”.

Abstract: The invention concerns a device for localizing a closing fault in landing doors equipped with locks that are electrically connected series. The localizing device includes a number of electric impedances (R0, R1, R2 . . . Rn) respectively mounted in parallel with said locks (120, 121, 122 . . . 12n), measuring devices (42, 44) for measuring the total impedance of the safety chain, microprocessor (46) which allow to compare said measured impedance with a cross reference table of floor impedances that provides all the impedance values of the safety chain obtained by opening one or the other of the landing doors, and display (48) which show the floor or floors on which the breakdown occurred.

Abstract: The invention concerns a device for displaying a virtual image, particularly of the control panel of an elevator cabin. The device includes a projector for projecting at least the virtual image of an elevator control panel from or near the cabin ceiling (13) onto a wall surface (9) of the cabin, in an appropriate position so that the virtual control elements (27) of the panel are recognized as such by the operator and by a control sensor for activating the control of the elevator in the classic manner.

Abstract: When a reference cage is designated at the time of determining the parameters which distinguish hall devices, reference cage determination device 1 determines as the reference cage the designated cage out of upper and lower cages, and the reference cage determined by the reference cage determination device is raised/lowered to and stopped at a designated terminal floor by reference cage travel device 2. Then, parameter determination device 3 determines parameters based on the floor at which the reference cage determined by reference cage determination device 1 has stopped, and parameter transmission device 4 transmits the parameters determined by parameter determination device 3 to the hall device of the floor at which the reference cage is positioned.By so doing, the setting of hall device parameters can be readily performed at the time of installation or the time of maintenance/replacement of double-deck elevators which do not possess projecting floors.

Abstract: Retroreflective tape 28, 29 disposed on select positions on an elevator guide rail 13 is sensed by infrared transceivers 24, 25 disposed on an elevator car 10 to provide a signal indicative of the elevator as being at a vertical position in a hoistway designated by said retroreflective tape.

Abstract: Hall call apparatus for a low-cost, low rise simplex elevator, all disposed on the hoistway doors, include a slider 25 which is released by depression of a hall call button 21 so that it is pulled upwardly by a spring 49 until it engages a stop 50. A clapper 33 overtravels when the slider stops and contacts a bell 34 to provide an audible indication that a call is registered. Holes 23, 24 in the hoistway doors form a chevron-like pattern through which colored chevron-like stripes 28 on the slider will show, to provide a visual, directional indication of the registration of the call. A passive transmitter disposed on the slider passes through flux of a permanent magnet 30 to cause a unique RF signal transmission from an antenna 31 that is picked up by an antenna 71 on the elevator car to indicate the floor and direction of the requested hall call, which may simply be applied to the car operating panel to force a car call in order to answer the request for service at a given floor.

Abstract: An elevator car operating panel (8), for a visually impaired passenger includes an upper floor input button (9), a lower floor input button (10) and an input confirmation button (11).

Abstract: A display apparatus within elevator cabs or elevator waiting areas that facilitates the simultaneous display of advertising and general news information is described. Broadcast from a remote control center, advertising and general news information updates are transmitted to, and stored in a server located within a building and then forwarded to a display memory and subsequently displayed on a monitor according to a remotely modifiable program schedule. The display is updated such that it contains a copy of the latest broadcast schedule, as well as the advertisement and information programming, and automatically displays a days program according to the most current broadcast schedule. The display units as well as the building server are each individually addressable thus allowing groups of displays to be simultaneously updated from a remote centralized location with information such as news updates, customized advertising information and the like.

Abstract: A hoisting rope for an elevator includes a plurality of longitudinally spaced, discrete targets retained within the rope. The targets have a characteristic that may be monitored by a device that is responsive to that characteristic. In a particular embodiment, the targets are formed from a magnetically permeable material and the monitoring device responds to changes in the magnetic field as the target passes the monitoring device. In another embodiment, the targets are formed from material that reflects electromagnetic energy. In this embodiment, the monitoring device emits electromagnetic energy and is sensitive to the energy that is reflected back from the target. A method to inspect the hoisting ropes includes the steps of positioning the monitoring device proximate to the hoisting rope, moving the hoisting rope relative to the device, and monitoring the targets to determine the spacing between targets. Changes in spacing are indicative of stretching of the rope, and thereby degradation of the rope.

Abstract: A procedure and apparatus for the measurement of elevator load uses a load measuring apparatus. The elevator comprises an elevator car (17) travelling along guide rails (2) in an elevator shaft, a counter-weight (20), a hoisting machinery (18, 19), a control unit, and hoisting ropes (11) attached at least by one end to an anchorage (21) in the elevator shaft. The load measuring apparatus (16) comprises a strain gauge (15) which outputs an electric signal corresponding to the load. The load measuring apparatus (16) is attached in conjunction with the anchorage (21) of the hoisting rope ends to a fixed place in the elevator shaft.

Abstract: The present invention relates to an elevator control system, comprising a plurality of car position indicators and car indicators for displaying a current floor position information of a car; a plurality of hall call buttons and car traveling operating panels; a plurality of floor controllers and car controllers (or car controller group) for controlling an information signal's input/output of a floor or a car, as well as for storing a group identifying information and an individual identifying information; an elevator controller, a hall signal transmitting repeater and a car signal transmitting repeater for relaying an information signal among the controllers; and a plurality of serial communication lines.

Abstract: A building having a plurality of floors, a plurality of detectors, such as smoke detectors, located on the floors, and an elevator system usable for moving building occupants between floors during an emergency condition, such as a building fire. The elevator system includes a control unit that controls movement of an elevator car between selected floors within an emergency evacuation zone for evacuation of building occupants to a designated evacuation assistance floor. The vertical movement of the elevator car is controlled relative to the detection of smoke within the building to increase the efficiency of emergency evacuation. The elevator and smoke detection systems are equipped with an emergency power source for operation in the event of a power outage. A signal control system receives status information from the building systems, including the elevator system, an air handling system, and a fire suppression system.

Abstract: A hoisting rope includes a plurality of longitudinally spaced, discrete targets retained within the rope. The targets have a characteristic that may be monitored by a device that is responsive to that characteristic. In a particular embodiment, the targets are formed from a magnetically permeable material and the monitoring device responds to changes in the magnetic field as the target passes the monitoring device. In another embodiment, the targets are formed from material that reflects electromagnetic energy. In this embodiment, the monitoring device emits electromagnetic energy and is sensitive to the energy that is reflected back from the target. A method to inspect the hoisting ropes includes the steps of positioning the monitoring device proximate to the hoisting rope, moving the hoisting rope relative to the device, and monitoring the targets to determine the spacing between targets. Changes in spacing are indicative of stretching of the rope, and thereby degradation of the rope.

Abstract: A communications system for an elevator system has a master control unit located close to the lift controller and connected via a bus to a number of local modules, each connected to one or more announcement devices. The announcement devices may be of various types including alphanumeric display of elevator position or other messages, lanterns indicating direction of travel, electronic gongs and passing chimes. The bus consists of only two conductors which carry both power and output signals from the master control unit to the respective local modules, the signals being encoded by modulation of the power supplied. The system reduces the amount of wiring required for new installations of elevator systems and also facilitates retrofitting to existing systems to install dot matrix display devices or audible announcement devices without the need for additional wiring.

Abstract: An apparatus and a method for installing and maintaining elevator system controls includes a storage card (1) having a storage element (2) in which elevator control data is stored. An elevator installation becomes operational upon inserting the storage card (1) into a control point (10) of an elevator control system (11). The storage card (1) can fulfill further functions, such as.sub.1 for example, the monitoring of maintenance utilizing a trip recorder for indicating that maintenance is due after a predetermined number of trips of the associated elevator car.

Abstract: For elevator car dispatching scenarios, the standard remaining response time (RRT) estimation is augmented by a selected amount of time where a horizon floor is to be served before reaching the hall call to be assigned. The augmentation may be made by adding a fixed RRT penalty, by assuming a car call stop after the horizon floor at a selected floor, or by using a neural network.

Abstract: The method for transmitting messages in an elevator communication system selects a set of elevator cars from a plurality of elevator cars in the elevator system, and compares present data for the selected set of elevator cars with data stored in a single table. The present data which differs from the data stored in the table is designated as changed or differing data. This differing data is transmitted to the plurality of elevator cars. Along with the differing data, retransmission data ordered according to the priority associated therewith is also transmitted along with the differing data. In this manner, a group communication controller controls the communication for several elevator cars.

Abstract: Automatic gain control is provided for a control means for controlling a magnetic actuator for an elevator horizontal active suspension. The gain is varied depending on the drive current in the coil of the electromagnet of the magnetic actuator, the airgap of the magnetic actuator, or both.

Abstract: A landing control system comprising an elongated nonmagnetic strip extending vertically along the length of the shaft, having along its length, at predetermined sites, magnetic adhesive tape containing coded information. A sensor for reading the coded information is mounted on the exterior of the elevator car grasping the nonmagnetic strip by a pair of tape guides, the guides being spaced as to permit the centrally located magnetic adhesive tape to pass freely into the sensing area without, while avoiding contact with the tape.

Abstract: An elevator call button senses the position of a push button by means of a photoreflective sensor, thereby eliminating the need for a mechanical switch.

Abstract: A reserve power system includes a reserve power machine (2) for the generation of power. The reserve power machine (2) is connected via a distribution network (4) to consumers (10,12) and elevator drives (8). The elevator drives include an elevator hoisting motor (28) and a frequency converter (26) controlling it. The elevator drives are provided with regulating devices (26, 44, 46) by means of which the speed of the elevator motor (28) is so adjusted that the power taken by the elevator drive (8) from the distribution network (4) is lower than an adjustable power limit (P.sub.A).

Abstract: An elevator controller 7 is provided with logic 48 which automatically calculates a motor time constant (.tau..sub.R) for a field-oriented current regulator/motor drive 20 by running the elevator up and down while computing an average of a sign-adjusted error signal DXD.sub.ERR for the up/down run and while varying .tau..sub.R and determining the value of .tau..sub.R at which the average of DXD.sub.ERR for the up and down runs equals zero within a predetermined tolerance. Alternatively, instead of computing the average of DXD.sub.ERR, a single elevator run may be used to determine the value of .tau..sub.R at which DXD.sub.ERR equals zero within a predetermined tolerance.

Abstract: A velocity-controlled elevator drive including an a.c. motor (28) driving elevator machinery regulated by means of a frequency converter (26) supplying the motor (28) with a controlled frequency and voltage. The load condition of the elevator is measured by means of a load weighing device (32) in the elevator car. A power limit (P.sub.A) is input to the elevator machinery as a reference value and the speed reference (38) given to the frequency converter is determined on the basis of the power limit (P.sub.A) and the load condition.

Abstract: The present invention relates to a method for transmitting messages in an elevator group control apparatus wherein a plurality of elevator controllers and a separate group controller transmit data using a covalent bus line. The invention comprises the steps of (a) transmitting, through the serial communication bus line, a data transmission period and a data transmission star point of each elevator controller, which are determined in accordance with the number of elevator cars connected with the serial communication bus line by the group controller, to the corresponding elevator controller; and (b) receiving the data transmission period and the start point which are transmitted through the serial communication line from the group controller; and (c) storing the data transmission period.

Abstract: A direction indicating device (4) for elevators is built into the door frame (3) near a floor door (1). The device (4) consists essentially of a retaining element (9), an up-direction arrow (10) and a down-direction arrow (11). In order to make the indicating device direction arrows (10, 11) visible from possibly all positions or viewing angles of the passengers on the floor, the device (4) is arranged on the door frame (3) three dimensionally with the direction arrows (10, 11) mounted on the front wall (14) as well as on the side wall (15) of the door frame (3). For further improvement of the visibility, another indicating device (4) can be arranged in a similar manner on the other side of the door frame (3). With the arrangement of this indicating device (4) on both sides of the floor door (1), a practically total visibility of the direction arrows (10, 11), through almost 180 degrees in the hallway, is assured.

Abstract: A method which provides for level monitoring of an elevator car within a hoistway at a plurality of floors by providing a plurality of sensed signals which is indicative of an elevator position of the elevator car relative to a plurality of targets having a plurality of light absorptive surfaces and a plurality of light interactive regions, the plurality of targets mounted within the hoistway at the plurality of floors. The plurality of sensed signals is processed to provide a leveling variable, a floor number variable and a direction of travel variable which indicate a direction of travel of the elevator car within the hoistway. The leveling variable, floor number variable and direction of travel variable are stored at a remote elevator monitoring central processor.

Abstract: An elevator rope speed monitoring assembly is disclosed. The rope speed monitoring assembly includes a plurality of sensors that monitor the movement of the individual ropes. The sensors output a signal indicative of the speed of the movement of the ropes. A controller compares the relative movement of the ropes and generates a warning signal if a sufficient deviation between relative rope speeds is detected.

Abstract: In a vertically movable elevator group management control apparatus for control of a plurality of transversely shiftable cars among plural shafts, control is done by storing route data with respect to each said car, generating target floor data including a target floor, based on car call data obtained in correspondence with each said car and station call data as obtained correspondingly to each floor, estimating the time taken for said car to reach said target floor, based on at least said route data, said target floor data and said car call data, and assigning a certain car to a certain floor call, based on the estimated arrival time.

Abstract: Even if rope (13) and spring (15) oscillate, to suppress these oscillations as much as possible.An elevator system is equipped with a car (1) that is installed such that it can freely move up and down in a hoistway, a sheave (14) that is installed at the top of the hoistway, a rope (13) for pulling the car that is suspended from this sheave (14), a suspension rod (9) to which the end of this rope (13) is attached, a spring (15) for damping vibrations which is installed between this suspension rod (9) and the car (1), a cylinder device (16) which attenuates the vibrations and has a flow volume control valve (22), a rotary encoder (24) for detecting the position of the car (1) in order to calculate the length of the rope, a load sensor (25) for detecting the load of the car (1) and a control panel (23) which calculates the characteristic vibration frequency f of the rope (13) from the length of the rope, the characteristic vibration frequency f.sub.

Abstract: An apparatus for efficiently managing a plurality of elevators in a group management apparatus in which input and output devices that are mutually related are combined into one group and connected as a network, which does not require any complicated wiring and thus the utilized equipment, repairing and maintenance of the overall elevator system are simplified.

Abstract: An air supply system may supply air into an elevator building and into the elevator. The system includes a number of frames each having a number of openings communicating with an air passage formed in the elevator building. One or more tubes are disposed in the elevator building for communicating with the air passage. An air generator is coupled to the tube for supplying air into the tube and for supplying air into the air passage and the elevator. A heat resistive panel assembly is secured to the wall and spaced from the elevator for forming an air chamber and for protecting the elevator from being burned by the fire.

Abstract: A mobile communication system including operation management of traffic machines, includes mobile radio terminals for receiving predetermined communication data, and which can be carried by a user of mobile communication; at least one traffic machine for transporting the user having the terminals; an operation management element for managing operation of the traffic machine by operation management data which are generated from predetermined operation data; and a line management element for managing radio lines used by the terminals on the basis of any one of position data and position change data of the terminals.

Abstract: A reflector mounted in an elevator shaft and having coded symbols in two tracks in the region of a stopping floor is read by detectors on the car for bridging door contacts when the car is in the arrival region and the resetting region of the stopping floor. The symbols are detected and evaluated by a two-channel evaluating circuit having optical transmitters for illuminating the tracks and charge-coupled device sensors for detecting the reflected images. A pattern recognition logic system and computers for each channel recognize patterns in the images for generating car position and speed information and for actuating relays to bridge the door contacts.

Abstract: An acoustic signal in an elevator door system is provided if a door close signal is present and a door has not closed within a determined time. A switching frequency of a pulse width modulation signal is reduced such that a motor is caused to provide the acoustic signal.

Abstract: A remote control arrangement (and method) for generating a car command remotely, includes a wireless transmitter and a wireless receiver which is coupled to an elevator controller. The receiver is detachably connected to wiring which leads to the controller. After finishing use of the transmitter/receiver arrangement, elevator service personnel detaches the receiver from the elevator wiring leading to the controller.

Abstract: A cab having a wheeled carriage fixed thereto is moved between rails on an elevator car frame and similar rails on a wheeled bogey. The ends of the rails are scarfed in a complimentary fashion so as to provide a temporary half-lap joint between the rails of the bogey and the rails of the car frame. Motion is provided by linear motors having active primaries disposed on the car frame and the bogey and passive secondaries disposed on the cab carriage. Motor control is in response to position signals provided by magnetostrictive linear displacement transducers. The cab carriage includes rollers on vertical axes which contact the insides of the rails for guidance. The cab carriage wheels and rollers are disposed in pairs separated sufficiently so that at least one roller and one wheel of each pair is in contact with a full rail as the carriage crosses the rail joints between the car frame and the bogey.

Abstract: A method for performing a correction run by an elevator system having an elevator car following a loss of an elevator car position information includes: detecting a terminal landing magnet in response to the loss of the elevator position information; moving the elevator car away from a predetermined terminal landing until the terminal landing magnet is not detected; running the elevator car toward the predetermined terminal landing in response to not detecting the terminal landing magnet in said moving step; detecting two magnets simultaneously in response to running the elevator car toward the predetermined landing terminal; stopping the elevator car in response to simultaneously detecting the two magnets; and resetting the elevator position information in response to said stopping step.

Abstract: An elevator drive fault detector for detecting operational faults in an elevator drive having an inverter and only one circuit breaker includes a current sensor, a monitoring device, a control device and an operational control system. The current sensor provides a current sensor signal. The monitoring device determines if an operational fault exists in response to the current sensor signal and provides an operational signal. The monitoring device disables the operational signal if the monitoring device determines that an operational fault exists or if the elevator drive fault detector performs a system check operation. The operational control system provides both the run command and an operational check signal and is responsive to the operational signal such that if the operational signal is disabled then the operational control system opens the one circuit breaker and disables the run command such that the control device disables a PWM signal.