Nord Geared Motors Crucial for Automatic Sorting System

Specializing in the delivery of express parcels, Chronopost employs more than 3,500 people across the world. The Chilly Mazarin hub, to the south of Paris, is the heart of the Chronopost network, and one of the top performing express sorting centers in Europe, with a maximum capacity of 30,000 parcels per hour. More than 60 percent of Chronopost's French parcel traffic is handled there. Every day, 500 crates containing parcels of all kinds are delivered by lorry to the unloading bays. On average, this represents 170,000 parcels needing to be identified, sorted and dispatched to the correct loading bay. The annual peak comes during the Christmas period, with 300,000 parcels to be processed.

With huge amounts of technology packed into its 13,000 m², the hub has 34 unloading and 83 loading bays. It has an automated two-level sorting system, with two sorters each running a length of 650 m. Parcel bar codes are read automatically on five sides by digital cameras. More than 1,100 Budde conveyors transport the parcels through the hub. The Nord Drivesystems geared motors are being used to drive these conveyors, either via bevel gear or worm gear mechanisms. They are all fitted with SK-type decentralized inverters, mounted directly on the geared motor casing.

"The solution proposed by Nord, which consists of decentralizing control of each motor to the motor itself, has two advantages. Firstly, there are space savings. It does away with the very large electronic control cabinets, which we would have struggled to accommodate. The wiring inherent in these cabinets also disappears, along with its associated size constraints and snagging risks," says Eric Fouquet, servicing and maintenance manager at the Chilly-Mazarin and Roissy hubs.

The geared motor inverter communicates via a Profibus fieldbus with a PLC (Programmable LogicController), which then sends the information on to the control center. Correct control and synchronization of the Nord Drivesystems is a key requirement, because each parcel must be processed, i.e. identified and directed to the correct loading bay, in less than three minutes. Each parcel is registered at the beginning of the line and tracked step by step along the sorting chain. There are up to three feed points for a single conveyor line, which was a world first for Chronopost when the hub went live. Similarly, a single sorter can have up to four feed points. If a backlog is registered at a particular loading bay, it is even possible to slow the chain so that the conveyors then serve as a storage centre, thus avoiding a log jam. Nord Drivesystems' new SK200E inverter range has been designed for mounting directly on the motor terminal box, producing fully integrated drive units. They have a number of basic functions, such as open-loop vector flow control, an integral brake chopper and an electromagnetic brake control. They also incorporate the processing of signals from an incremental or absolute encoder, and an integral POSICON axis positioning function.

"We only want Nord Drivesystems on this hub. Quite apart from the technical quality, we're particularly pleased with the flexibility and service their teams provide. It's very easy to get through to a technical engineer, and whenever we have a problem or a query, they can be here in less than 48 hours. Even though it is very rare for a geared motor to break down, we have a permanent stock of replacement parts so that we can immediately change any defective unit," adds Fouquet.

The goals for 2011 are particularly ambitious, as the aim is to increase to an average of 200,000 parcels a day, which is a 20 percent increase. To achieve this, the building will have to be extended. This will allow the packaging sorting and compacting equipment to be removed from the actual hub itself. The additional space made available will make it possible to free up the loading bays and increase throughput.