#variabletroque

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Closed Loop Feedback Control of Feed Conveyors with Variable Frequency Drives

In this example, we are controlling the supply of material (stone) via the feed conveyor speed. This indirect control of the larger fixed speed process (stone crusher machine) will enhance the application for maximum production.

The stone is fed into the crusher by a feed conveyer, which is driven by a motor that is controlled by a variable frequency drive. The crusher has a motor that is running at fixed speed. We can monitor the input load of this fixed speed crusher motor using a simple current monitor. Depending on the input load signal, the feed conveyor speed is automatically adjusted to optimize the amount of stone entering the crusher.

The amount of stone on the feed conveyer randomly changes in quantity which causes the load on the crusher motor to vary depending on the amount of stone it receives. Using closed loop control, we can speed up the feed conveyer if the load on the crusher motor is low, or slow it down if the crusher motor load is high. Since the crusher is now running at its maximum load setting all the time, the production output is greatly increased! The integration of variable frequency drives in applications like this pays for itself in a matter of months!! Other similar applications include wood chip5 conveyors, powder manufacturing, sugar cane crushing, etc.