Moving more things than ever before
The conveyor belt began life in the late 1800s, essentially for transporting coal and ore. In the 1900s its scope broadened from mining to assembly lines in the car and aerospace industries. Some companies developed particular types of conveyor belts to suit their specific requirements.
Today the uses are numerous, including for moving large numbers of people along escalators and moving walkways in malls, and as a means for handling baggage in airports. The longest such system is 63 km and can be found in Dubai International Airport.
In the Maghreb, the world's longest conveyor belt system, which, at 98 km, can even be seen from space, transports phosphate from the Bou Craa mine all the way to the port city of Laayoune, from where it is then shipped around the world. It is a handy way of hauling continuous streams of ore in a region without roads and can move 2 000 metric tonnes of rock per hour.
Used in many other industries, such as food, electronic, pharmaceutical, chemical, bottling and canning and packaging, they’ve also made their way into the gym in some fitness machines, pull your shopping items from the basket to the check-out, and give restaurant goers the fun conveyor belt sushi experience.
Conveyor belt technology offers a cost-effective, energy-efficient and eco-friendly way of moving people, products, raw materials from one place to another. In the latter case in particular, such systems produce less carbon dioxide than road or rail transport.
Technology that delivers the goods
Simply speaking, conveyor belt systems comprise two or more pulleys and the carrier belt that rotates them about. One or both pulleys are powered by motors and control systems. There are different types of conveyor belt systems depending on what items are being transported, i.e. boxed materials in factories or raw materials, such as grain, salt or ore.
They can run horizontally or up inclines at mines or in commercial buildings or curve around corners. The belt itself can be made of woven fabric, rubber, metal or rollers, depending on the items being moved and the path the belt follows.
Several IEC Technical Committees (TCs) prepare International Standards which cover specifications, design, manufacture, use, test methods, efficiency and reliability of these components.
Some of the motors which drive the conveyor belts are covered by the work of IEC TC 2: Rotating machinery, which deals with the specifications for motors (and generators) of all sizes.
There are instances when conveyor belts need to change speed, for example if an escalator is not being used, to save energy, wear and cost, or if an item gets jammed along the belt. This is achieved by varying the frequency and voltage supplied to the motor, via a frequency converter. IEC TC 22: Power electronic systems and equipment, prepares International Standards for power drive systems (PDS), equipment and their components for electronic power conversion and electronic power switching. This means the control, protection, monitoring and measurement of systems using frequency converters, which allow speed to fluctuate.
Arriving safe and sound
Industrial conveyors are often equipped with trip cords that run the length of the system and allow workers to immediately shut it down if there is a problem. Warning alarms or recordings alert users on moving walkways as they enter or exit.
Sensors detect objects or people blocking conveyor belts or moving walkways, and send a signal for the system to slow down or completely stop. The work of IEC TC 47: Semiconductor devices, for sensors and other systems, ensures sensors are dependable and function safely.
Quieter, cleaner, more efficient
Increasingly, laws and regulations call for electrical motors of high efficiency, as well as with a greater percentage of variable speed applications. IEC TC 2 continues to improve energy efficiency through its IEC 60034 series of International Standards, defining efficiency classes for all alternating current (AC) motors, which can be powered directly from the mains.
These classes are a simple way to see whether or not a motor has reasonable, good or excellent efficiency. They make it easy for customers to specify what type of motor they want and allow legal authorities to set minimum efficiency requirements for complete markets. In addition, TC 2 is currently developing a new Standard of efficiency classes for variable speed motors that are specifically designed for converter supply.
Other advances for transporting raw materials over great distances include addressing noise pollution by using much quieter rollers and enclosing conveyor belts entirely.