At the outset of the project, there were four G1750 centrifugals from BMA with Simatic S5 controllers and Simovert A frequency converters. The project goal was to bring the electrical equipment up to date, using innovative concepts. Specific objectives included greater efficiency in both energy consumption and output, and the implementation of the latest safety standards. Once the contract had been awarded, engineering work started and a custom solution soon took shape.

Unlike with standard control technology, the control system was planned right down to the field level. A redundant controller was included to ensure reliability and maximum availability. This provides redundant communication with the control system and also at the field level via Ethernet. An additional control cubicle, such as is usually found in electrical rooms at a distance of up to 100 m from the centrifugals, was deliberately omitted. All components were arranged on the centrifugal itself and designed for an extended temperature range. This made the installation work for the conversion far easier and less costly. All safety technology was designed in accordance with European standards and the relevant professional association’s regulations, ranging from the redundant sensors to the safety controller and to the redundant control of the drive actuators.

Frequency converter for greater energy efficiency

During this time, the frequency converter was also designed. A so-called DC busbar converter was chosen, which comprises two active input modules that create the DC link voltage. The DC voltage is supplied to the motor modules (the actual frequency converters) via a single busbar, which enables direct energy exchange between the motor modules, thus minimising power losses within the system. With this type of energy exchange, far smaller incoming feeders can be used and their output can be lower than the total output of the connected motor modules. This solution makes for very grid-friendly operation. Other benefits include a far smaller footprint, fewer incoming feeders and a high level of flexibility of plant extensions.

In order to control the energy flow in the converter, an innovative energy management system was also developed. This permits operation of the four BMA G1750 centrifugals for either batch efficiency or energy efficiency. In “batch efficiency” mode, the focus is on producing the highest possible number of batches per hour. In “energy efficiency” mode, on the other hand, smart regulation of the motor modules optimises the energy flow in the converter in such a way that a minimum of energy is taken from the grid.

BMA reaches ambitious targets

Late summer 2013 saw the installation and commissioning at the Nordzucker site. Production could start in time for the campaign and benefited from this highly efficient and versatile concept. Nordzucker have said that all of the very ambitious targets were met and expectations even exceeded.

CUSTOMER BENEFITS

• Reduced costs thanks to operation in batch efficiency or energy efficiency mode
• Better system availability
• Grid-friendly operation
• Small footprint

Sven Weidner
BMA Automation
sven.weidner@bma-de.com