Greater Efficiency for the Butchery Trade

We had already had a good experience with Eaton's HMI/PLCs and are now using the PowerXL DC1 variable frequency drives
- Jörg Schwebel head of electrical engineering at Günther Maschinenbau


Background
Pickling has been a method of preserving meat and sausage goods since ancient times. The pickling salt slows down the growth of microorganisms, of which some may be a risk to health. The meat is also provided with a special aroma, depending on the additional spices mixed in. A wide range of different methods can be used for pickling. However, with the traditional method, in which the goods are pickled dry or wet, the process may take several weeks. In order to speed up this process, techniques are normally used today in which the pickling salt is injected in liquid form directly into the meat.

The Dieburg-based company Günther Maschinenbau GmbH specializes in the development and manufacture of machines for the food industry, and is one of the market leaders in the meat sector, particularly with large industrial plants. When it was decided to further develop the pickling injectors for small to medium-sized butcheries, one aim was to offer the customer added value through the provision of automation and also a more energy-efficient machine design.

Challenges
The pickling injectors in the market sector for the butchery trade are normally fitted with around 15 to 60 injector needles. The machine uses these needles, which are pressed into the meat in strokes using a needle head, to inject the pickling brine into the product.

Previously, the injection pressure for the pickling needles was manually controlled via a mechanical bypass. In other words, the user set the required pressure by means of a pressure gauge, while the electric pump continuously supplied the pickling brine at full load. The difference to the maximum pressure was released into a tank via a threeway valve so that only a certain percentage of brine was used for pickling the meat. In order to achieve a more efficient machine design, Günther Maschinenbau decided to control the 1.5 kW pump in future using a variable frequency drive.

Solution
For this task, Eaton’s new PowerXL series greatly impressed the machine builder. The DC1 is used, which is designed for motor ratings from 0.37 to 11 kW and was developed for applications where robust design, availability and universal functionality are the main requirements.

“As the space in our pickling injectors is very limited, the construction volume was a key criterion for us,” explains Jörg Schwebel, who is responsible for the electrical engineering at Günther Maschinenbau. “We also wanted to ensure that the communication with our controller is easy to implement and the solution is costefficient.”

The DC1 is a very compact and at the same time powerful device that controls motors by means of the V/f characteristics and also enables an increased torque. This allows the user to also run the motor at 150% of the rated power for 60 s and at 175% for 2 s. Self-explanatory type codes, autotune functionality and convenient parameterization (with only 14 standard parameters) simplify configuration and commissioning. As well as programming via the keys on the device or alternatively via a PC, the machine builder can copy the parameter settings from one device to another quickly and simply using a Bluetooth PC stick with an RJ45 interface.

The PowerXL variable frequency drives come as standard with the Modbus RTU and CANopen fieldbus system, so that the controller of the pickling injectors can communicate directly with the DC1. The variable frequency drive is also able to exchange data with the pressure sensors via its analog inputs. The position limit switches of the needle heads are scanned directly by the DC1 via its digital inputs.

Results
Because the injection pressure is now controlled by the variable frequency drive, this can be adjusted considerably more efficiently and precisely. “We now appreciate the achieved energy savings of at least 25%,” Schwebel states. He sees other benefits in the fact that the cabling required could be kept to a minimum, thanks to the versatile interfaces of the DC1 and the fact that the overall wear on the machine is considerably less. The pump no longer runs continuously at maximum, seals are subject to less load, bearings and guide rollers run slower etc. In this way, the end user also benefits from the reduced maintenance requirement and the longer machine lifespan.

With the mechanical bypass, the only possibility to control the injection quantity was using the parameter for injection pressure since the needle head always went up and down at a constant stroke rate. With the new solution, however, Günther Maschinenbau can now also change the speed of the needle since a second DC1 controls the stroke movement of the needles. The cycle rate is thus infinitely variable with a range between 10 to 65 strokes a minute. Instead of having to run several pickling cycles, the end user can now speed up the process, thus saving time and effort.

“Günther Maschinenbau is the first company since 2013 to offer this trade sector this kind of automated machine,” Schwebel says. “The response from our customers has been very positive and we are hoping to gain the competitive edge on the market with this solution. We are therefore also planning to automate in future other machines of ours such as tumblers – also with Eaton on board.”