Control device for lifting magnet
AssigneeKobelco Construction Machinery Co., Ltd.
InventorsNatsuki Yumoto, Hideki Yoshihara
Life of this patent
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Abstract
When at least one of a value a detected output current to a magnet and a magnet load defined by the following formula is equal to or larger than a threshold value predetermined for the value of the detected output current or a threshold value predetermined for the magnet load, a controller constituting a control device outputs, to a control circuit, a command to decrease voltage applied to the magnet from next attracting operation. Magnet load=excitation ratio×I×V . . . ; wherein excitation ratio: excitation time/(excitation time+non-excitation time); I: value of the output current; V: voltage applied to a lifting magnet.
Claims6
A control device for a lifting magnet, the control device comprising:
- a control circuit for controlling power supply from a power source to the lifting magnet;
- a current detector for detecting output current to the lifting magnet;
- and
- a controller for receiving a signal from the current detector and outputting a command to the control circuit,
- wherein when at least one of a value of the detected output current and a magnet load is equal to or larger than a first threshold value predetermined for the value of the detected output current or a second threshold value predetermined for the magnet load, the controller outputs, to the control circuit, a command to decrease voltage applied to the lifting magnet from next attracting operation, wherein the magnet load is defined by:
- Magnet load=excitation ratio×I×V, wherein
- Excitation ratio:
- excitation time/(excitation time+non-excitation time),
- I:
- value of the output current, and
- V:
- voltage applied to the lifting magnet.
Dependencies are inferred from the claim text.