Fieldbus Modules Control 120 Drives in a pallet Conveyor System

16Jul

PCA Roboter- und Verpackungstechnik, located in Southern Germany, specialise in customised palletising solutions and packaging conveyor systems. The company primariliy serves the food and beverage industry, but also works with other industries such as chemical and pharmaceutical manufacturers and consumer goods industry

When a Food and Beverage industry customer approached the company about a conveyor system that is installed in a 90 metre long cooling tunnel, PCA were confident that Murrlekronik’s system specialists would design a tailor-made solution using the best in automated technology.

Cooling tunnel for a Food & Beverage Manufacturer

In Autumn 2010, PCA received an order for their most complex project to date: A major food producer needed a 200m pallet conveyor system with a conveyor capacity of up to 80 pallets per hour. 90 metres of this system were going to be situated in a cooling tunnel. Along with the conveyor system, PCA supplied both a packaging system and seven palletising lines. After leaving the palletising system, situated behind the production line, the pallets containing fresh produce at 10C reach the cooling tunnel. The cooling units in the tunnel cool the air down to -10C. As the pallets of fresh produce move slowly forward through the tunnel heir temperature is klowered to 2C. Care is taken to make sure the produce is not frozen during is journey. Upon exiting the cooling tunnel, the pallets are either stored at -24C in a deep freeze warehouse or transported to the shipping department.

The speed of the conveyor line is conrolled by 120 drives. The motors are controlled by Cube67 RS232/485 modules. These modules feature four digital I/O ports. They connect to light barriers that detect the position of the pallets. The target temperature is selected by a preset time. There are two conveyor racks in the cooling tunnel: the left track has two pallets moving as a set while the right track is designed as an „express track“. The destination and other data required for the transport are stored in the system’s control software.

Decision on Cube67

The total system covered a very long distance, so the desicion had to be made whether to use conventional technology or choose a bus system. The conventional method meant having a frequency converter in the cabinet and wiring the drives with very long cables routed from the cabinet to the drives. Nigel Greaves, System Sales and Technical Manager for Murrelektronik Ltd UK confirmed that „the decision to install a Profibus solution was made very quickly since a space saving solution was required for controlling the drives“ Then following initial consultations with Murelektronik GmBH, PCA were confident that Murrelektronik’s fieldbus technology, specifically Cube67 would be the most economic solution for a decentralized installation.

Nigel Greaves explained „Because of their compact design, Cube 67 modules can be easily protected from damage with simple means, like stable edge protectors. Another prerequisite for the application in the cooling tunnel was being IP66 compliant. Cube67 modules, with their IP67 rating, meet these requirements.“

Quick Installation with Pre-wiring

Five months after the project start, PCA was able to set up and test the conveyor system in their own production hall and demonstrate its capabilities to the customer. Four months after the demonstration, the system was shipped, assembled at the food manufacturers’s site and put into operation. Dieter Hubner, managing director of PCA explained that „ the Assembly and set up time took about 4 weeks and the complete electrical setup at the customer’s site took one week. Such a short time for such a complex system with a lot of data handling was possible because of Murrelektronik’s preliminary work“. „Thanks to the plug connection technology we were very fast. All we had to do was install the connection cables, everything else was ready. The drive was pre-wired: on-site we only had to connect the Cube67+ bus node with pre-wired cables to ensure faultless wiring“.