INVT VFDs Applied to Conveyors in the Cement Plant

Conveyors:

Conveyors are found in almost every cement plant. As shown in the picture, conveyor load is transporting raw-material / coal and cement. The environment is demanding and there is always a risk of damaging the belt by overstretching, slipping or breaking.

Fig.1 Conveyors in the cement plant

Advantages for INVT VFDs driving:

1.Extended lifetime and increased availability

VFDs provide accurate torque and speed control of conveyors. This reduces the stress on mechanical equipment such as gearboxes, pulley and belts, especially during start-up and stopping, as well as during operation and maintenance.

2.Significant energy savings

Starting and stopping conveyors with variable speed drives does not cause additional stress to the equipment. Therefore, conveyors can be stopped or operated at reduced speed if material demand is intermittently resulting in decreased energy consumption. VFDs are not running at full speed, the speed is changed with copper ore production. Comparing with full speed running, there is lots of energy saving.

3.Smooth ramp up

VFDs provide a smooth ramp-up of conveyors. They deliver high starting torque for the current drawn from the power system and have a programmed upper limit to reduce peak torque during the startup of the conveyor. The low starting currents and high starting torque enable smooth startup of the conveyor, even when it is fully loaded.

4.Low-speed operation for belt inspection

For maintenance inspection about belt changes and repairs, it is possible to run the conveyor belt at low speed.

5.Accurate and fast load sharing

INVT VFDs provide an accurate and fast load sharing between several drives. This is useful for conveyor applications, where two or more motors operate on the same conveyor belt, making sure all motors are loaded as needed. The converter control provides a window speed limitation to prevent belt slippage.