Zest and WEG automated conveyor driven by frequency converters Africa's largest

Ecologically sound system of the conveyor belt reduces the environmental impact and saves energy. The partnership with Anglo Thermal ZEST allowed to adjust the project reducing maintenance time and also increase productivity.

The great length of the conveyor belt Zondagsfontein presented many challenges due to its 16 km and a capacity of 1750 t / h. It was necessary to place drive pulleys on both ends of it.

The main drive pulleys are driven by four sets + drive motor of 500 kW while the secondary drive pulleys are powered only by two.

The handling of the torque data of primary and secondary pulleys was done through the master / slave configuration, which uses network communication FieldBus by a fiber optic cable and is also integrated in the automation and customer structure .

WEG was responsible for programming the motor sets + frequency converters, providing full compatibility with customer system. This means that the central control room receives feedback signals such as speed, torque, current, power and alarm of engines and drives.

Commissioning and initial operation was highly complex tasks. The secondary part of the tape was kept standing for two minutes while the main body began to spin.

The six motors operate at low speed for about one minute at boot time to allow the stresses of balancing tape before the tape can be accelerated to full operating speed.

During normal startup, the four main drives must operate with torque similar, and both side drives.

But the torque and speed of primary and secondary drive are substantially different. So, once the tension of the belt is stabilized, the six drive torque and speed must be equal. The torque of an engine of 500 kW is potentially large, so it is extremely important to accurately control the charge distribution in the different engines. The solution WEG said these complexities were addressed.

After the initial startup, normal operation requires that the main drive pulleys booting first and secondary pulleys 20 seconds after booting.

During this time, the speed is limited to about 70 rpm to ensure that the load is balanced and after five minutes accelerate to its maximum speed of 4.7 meters per second.

Implement this control with a frequency converter enables the best performance by decreasing mechanical abrasion factors and enabling more energy saving.

The frequency converter series of WEG CFW-09 technology adds the world's most advanced drive for induction motors AC.

The Vectrue Technology enables new generation of WEG inverters combine the techniques of control scale V / F control and closed loop vector (with encoder) in the same product.

The open loop vector control allows fast dynamic response with high torque (torque) and the mode of self-adjustment means that there is an automatic parameter to adjust the drive motor and the load vector modes.

The frequency converters are equipped with a compensation technique while avoiding the instability of the engine, providing increased torque at low speeds.

The system is fully operational and the mine now has a higher level of security. In terms of energy expenditure, the mine will recover the money invested in the installation of the conveyor belt in record time. This will result in significant savings and reduce the impacts of the coal operation. The mine is currently in beta testing, and the tape has been tested up to 1250 t / h without presenting any problems.

A second conveyor belt was laid up in the same place across four frequency converters of 750 kW WEG in a master / slave configuration. The power consumption is similar to another facility with the only difference in the length of the tape.

Tags: frequency converters , automated conveyor driven , conveyor belt , drive pulleys , belt is stabilized ,