Electricity: motive power systems – Open-loop stepping motor control systems
Patent
1994-09-27
1998-04-07
Cabeca, John W.
Electricity: motive power systems
Open-loop stepping motor control systems
318557, 307143, H02P 720
Patent
active
057368279
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is the US national phase of PCT application PCT/EP93/00863 filed 7 Apr., 1993 with a claim to the priority of German application P 42 14 431.0 filed 30 Apr., 1992.
FIELD OF THE INVENTION
The invention relates to a motor-driven step switch. More particularly this invention concerns such a step switch which includes a drive motor connected to the step switch and a controller for actuating the drive unit in accordance with rotation direction as well as an information unit which recognizes and transmits the switch position and which is electrically connected with a controller which produces the signals for activating the control of the drive motor.
BACKGROUND OF THE INVENTION
Such motor-driven step switches are known from German open application 2,410,641.
The motor drives of these step switches are constituted as a drive and an information unit; the main part of the drive unit is a drive motor--normally a polyphase asynchronous motor--which is switched by a protective controller in accordance with rotation direction and which on reaching the respective set-point voltage step of the step switch is cut off from the line and short circuited. In addition a hand crank is provided for manually actuating the step switch when necessary. The information unit has means for determining the actual position of the step switch, for example a tachometer or position switches for each possible step, which determines the rotation and rotation direction of the drive shaft.
To actuate the step switch, that is for controlling the protective or other controller in the known step switches the motor drive is connected via electrical lines with a controller. In this known controller a signal for actuating the controller is produced depending on any deviation between the desired and actual voltage on the transformer being operated as well as on further criteria, e.g. when controlling several step transformers on a common bus in parallel.
The disadvantage of these known step switches is that the motor drive has a multiplicity of electrical connections which must all be connected via separate electrical lines with the respective controller. These connections are necessary because quite a bit of information, for example for the actual determination of switch position, rotation rate, and rotation direction of the drive shaft and so on, must be produced in the motor drive by electrical or electromechanical means often at a large remove from the controller. Further conductors are necessary in order to make possible for example optical position indicators; finally further lines are needed to send the commands back from the controller to the motor drive which converts them into switching movements of the step switch.
This disadvantage is particularly grave when one takes into account that the locations in which the equipment is located and in which other indicators, e.g. banks of lamps, are provided is often more than 50m from the step transformer and thus from the respective step switch and its motor drive and that a group of up to 50 individual conductors must span this distance.
In fact this last-mentioned problem does not exist with so-called autotransformers such as known from British patent 2,109,960 where the controller is mounted on the transformer, but with such step transformers there remains the disadvantage of a multiplicity of electrical connections between the controller and the motor drive.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved motor-driven step switch.
SUMMARY OF THE INVENTION
This object is achieved according to the invention in a motor-driven step switch for step transformers which includes a drive motor connected to the step switch, display, input, and control means, a controller for actuating the drive unit in accordance with rotation direction, an information unit which obtains and transmits the step position and which is connected with the controller which delivers commands for controlling th
REFERENCES:
patent: 3553483 (1971-01-01), Jarvis
patent: 4162424 (1979-07-01), Zillgitt et al.
patent: 4300158 (1981-11-01), MorgenFruh et al.
patent: 4845594 (1989-07-01), Wilkerson
"Motor Drive Units MA7& MA9", Maschinenfabric Reihhausen, Sep. 94.
Dohnal Dieter
Okanik Peter
Stadelmayer Manfred
Cabeca John W.
Dubno Herbert
Maschinenfabrik Reinhausen GmbH
Wilford Andrew
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