Motor overload protection for cargo canopy systems
OwnerRory H. Chenowthinventor
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Abstract
In an installation controlling the operation of one or more motors driving a mechanism for deploying or retracting a protective canopy over the cargo compartment of a truck or wagon, a method and device for protecting the motor windings against excessive power use by measuring the level of drawn current with a digital ammeter. If the current exceeds a threshold level of operation, a timer is started. As soon as a given absolute safe period of operation is surpassed, a breaker switch is tripped interrupting the motor power supply. A plural number of trip points can be programmed into the device.
Claims19
A method for disabling an electrical motor when the amount of energy consumed by the motor exceeds a preset limit, said method comprising the steps of:
- assigning a plurality of threshold amperages of an electric current drawn by the motor;
- setting a time duration limit for each of said plurality of threshold amperages;
- measuring the amperage of the current drawn by the motor to get a measured current;
- detecting that said measured current has exceeded a first one of said threshold amperages and not exceeded a next larger one of said threshold amperages;
- accumulating the time said measured current is drawn;
- and
- interrupting a supply of said current when said limit for said first one of said threshold amperages is reached.
In an installation controlling the operation of a motor driving a mechanism for deploying or retracting a protective canopy over the cargo compartment, an improvement for protecting the motor windings against excessive power use comprises:
- a digital ammeter substantially continuously measuring the level of electrical current drawn by said motor;
- means for determining when said current reaches a threshold level of operation;
- a timer accumulating the time period the current remains at said threshold level;
- and
- means for tripping a cutoff switch as soon as a given absolute safe period of operation is surpassed.
Dependencies are inferred from the claim text.