Electricity: motive power systems – Generator-fed motor systems having generator control – Automatic generator control and/or with time-delay means
Patent
1997-03-07
1999-09-28
Ro, Bentsu
Electricity: motive power systems
Generator-fed motor systems having generator control
Automatic generator control and/or with time-delay means
318145, 318158, 361145, 414606, 414737, H02P 910, B66C 108
Patent
active
059594160
ABSTRACT:
An apparatus and method for controlling a lifting magnet (12) of a materials handling machine (10) to eliminate arcing between contacts (70-80) within the magnet controller (26) as well as large voltage spikes. The controller (26) selectively excites the shunt field windings (66,68) of a direct current generator (22). The magnitude and direction of the current passing through the shunt field windings (66,68) is varied by the magnet controller (26) to control the magnitude and polarity of the voltage at the generator output (23). The armature (60) of the generator (22) is rotatably driven by a hydraulic motor at an essentially constant speed to minimize voltage variations at the output (23) of the generator (22). The magnet controller (26) includes a programmable logic controller (40) which selectively opens and closes the contactors (70-80) within the controller (26). The programmable logic controller 40 is also connected to indicator lamps (L1-L5) within the operator's cab (14) of the materials handling machine (10), and selectively illuminates the lamps (L1-L5) to provide an operator of the apparatus with information regarding the status of the magnet control system (27) including the controller (26). A drop time adjustment control (81) is also positioned in the operator's cab (14) and operable to vary the drop time of the magnet controller (26).
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Chlad Kenneth J.
Clutter Ronald W.
Cooper Timothy L.
Robinson Charles A.
Caterpillar Inc.
Ro Bentsu
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