When the German Edeka chain wanted to upgrade its meat handling plant with a new conveyor installation, it took particular care in the choice of components, especially the power feeder system and associated spring connection technology.

“With the new power feeders, we were able to develop a conveyor system which is very different from that offered by our competitors,” said Josef Basic, co-proprietor of Reba-System, the company which supplied Edeka’s new meat handling installation. Basic and his corporate partner, Konrad Reich, focus on cutting-edge conveyor technology to address the demanding requirements of the company’s customers in the food sector. Eight patents registered by Reba-System underpin its innovative solutions.

For Edeka, Reba-System has developed transportation and washing system to ensure fast, clean and reliable handling of fresh meat. The system automatically empties, washes, dries and stacks up to 1500 crates per hour. A key objective in its development was that the electrical systems should be designed to minimise the possibility of faults. Since Edeka only has a small on-site service team, ease of maintenance was another important consideration.

“The Siemens Sirius3RV19 power feeder system, with its spring clamp connectors, offered us an ideal solution,” said Basic.

The modular system provides convenient power in-feed and distribution, using circuit breakers and complete load feeders with spring-clamp terminals. These are rated up to 5.5kW. If conventional screw-clamp connections are used, the system’s capacity is extended to include size S0 motor protection circuit breakers, with ratings up to 11kW.

In the Edeka installation, European standardised crates of sizes E1 and E2 are separated, washed and stacked in a high-bay warehouse with 15000 storage locations. The conveyors that transport the crates serve the whole building and have a total length of several hundred metres. More than 200 motors are used to drive them.

“To reduce spares requirements and to simplify maintenance, we used the same type and size of drive motor for all of the belts,” said Basic. “The motors are all rated at 0.25kW.”

To guarantee maximum system availability, the electrical installation is divided into 20 separate areas. With this arrangement, only one area is affected if there is a fault or if an emergency stop condition arises; the remaining areas can continue working normally. The installation comprises, therefore, one main control panel and 20 subsidiary panels. Communication between the panels is provided with PROFIBUS-DP links, which Reba fits separately.

“Standardisation and clear structure are the foundations of our success,” says Basic, “and it’s only necessary to glance at the panels to see the

well-structured arrangement of the electrical system which we have been able to achieve with the help of the Sirius3RV19 feeder system. This structure very quickly proved its worth during the commissioning process.”

In practical terms, the use of identical components throughout the panels brought another very important benefit – work could be started on building the panels even before the design had been finalised.

Modular system, 63A capacity

At the heart of the Sirius3RV19 power feeder system is a three-phase in-feed module which has provision for connecting incoming cables of up to 25mm2.

While ordinary ferrules can be used, one of the major benefits of the 3RV19 system is that they are not needed, allowing substantial savings to be made in wiring time.

The spring-connector technology used by the system provides dependable vibration-resistant connections, and eliminates the risk of wiring errors on the incoming side of the breakers.

All connections are automatically insulated from each other, and protection against shock hazards is provided as a matter of course.

The length of the baseplate used to mount individual feeders can easily be adjusted to suit particular combinations of contactors and breakers, and the baseplate itself simply snaps into place on standard mounting rail.

Feeder combinations up to a maximum load of 63A are supported, though this can be increased under certain circumstances.

In the Edeka installation, most of the feeders use Sirius3RT and 3RV contactor/breaker combinations, with the breaker mounted vertically above the contactor. Only the hoist lifts require reversing starters, which can be implemented either with a side-by-side or vertical arrangement of components. Side-by-side mounting was chosen for this application, as it allowed best use to be made of the available space.

For Reba-System’s Basic, finding the most efficient solution is of paramount importance, as smaller companies are even more reliant on making time and cost savings than their larger counterparts: “The new system cuts our design and assembly time by at least 20percent, but the way that spring clamps eliminate the risk of faulty connections is, potentially, an even bigger benefit.

“We estimate that a single faulty connection can cost as much as E5000 to trace and rectify – especially as we export a lot of our products.”

Easier service

The Sirius3RV motor circuit breakers used in the installation are fitted with auxiliary contacts. In the event of a trip, these contacts send signals to the PLC that provides overall control for the installation.

Since the PLC can be accessed via a modem link, this arrangement provides a simple yet powerful remote diagnostic function which, according to Basic, has proved extremely useful during the new plant’s first year of operation.

At Reba System, the development of new approaches and new technologies is one the company’s central objectives.

As Basic puts it: “We’re always looking for ways to make sure that we provide our customers with the best possible solutions.” In achieving this objective, Basic sees the Siemens Sirius3RV19 feeder system with spring clamp terminals as “an important and dependable partner.”

For more information, visit www.siemens.co.uk/automation