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Large glassworks in Croatia tackles harmonics and overheating with 15 ADF filters in Multimaster mode

Croatian Glassworks

LocationHum na Sutli, Croatia
IndustryGlass Packaging
CustomerAiP Automatika i procesi d.o.o
Timeline: 2021-2022


The Vetropack Group is one of the leading glass packaging manufacturer in Europe, with a workforce of around 4,000 people and nine glass factories in Switzerland, Austria, the Czech Republic, Croatia, Slovakia, Ukraine, Italy, and the Republic of Moldova. In 2019, engineers at the Vetropack Straža glassworks in Croatia, detected overheating of Power Factor Correction chokes, causing magnetic noise. Measurements were immediately performed, as well as a study of the harmonics situation within the site’s facilities. The study showed the presence of ferroresonance and THDu values ranging from 6% to 9% depending on transformer station. In 2021, Vetropack contacted AiP, Automatika i procesi d.o.o, Comsys’s partner in Zagreb, for additional consultations and possible collaboration.

Croatian Glassworks Production Power quality Challenges


After detecting the ferroresonance and overheating, Vetropack had decided to keep only Medium Voltage Power Factor Compensation. On the Low Voltage Side, the intention was to move to active harmonic filters as the best solution. The main challenge was the design phase and deciding how the filters should be operated. Installing additional current transformers was not possible, and AiP had to use the existing CTs. There are eight transformer stations in the Vetropack Straža grid. The main power supply operates at medium voltage, 10 kV, and can be supplied from two points on the national grid. The power quality problems were being caused mostly by the Variable Frequency Drives, Melting Furnaces, UPS systems and two-phase rectifiers. The most visible harmonics were typically the 5th, 7th, 11th, and 13th, but on some of positions also the 17th and 19th. Voltage drops caused by the national grid are also present.

Power quality challenge


It was determined that 15 active harmonic filters were needed in total, to be installed according to a very precise time plan spanning three months. To fulfill all the requirements of the customer’s specification, AiP in collaboration with Comsys decided to go with ADF P300-150/480_TCE41O—54 in Multimaster mode. In order for the system to work properly, summation current transformers were installed. The system was connected to the SCADA network to achieve control and to have a full view of the measurements and status of all ADFs installed. AiP is using digital input for start/stop signal, and two digital outputs for alarm and running/not running. The setup is closed loop, autostart on boot (due to power drops), autorestart on alarm, resonance limit.

Croatian Glassworks ADF Filters


Glass production is a highly complex process with significant energy consumption, and Vetropack is always focused on adopting the best practices in the industry. The main goal of this project was to extend the service life of installed equipment and reduce downtime. During commissioning, AiP was informed by the company performing the measurements about the rise of even harmonics (2nd, 4th, 6th and 8th). AiP presented this issue to Comsys and it was quickly solved with the new 2.2.0 software. 

Since then, all 15 ADFs are working as intended and the THDu on the Medium Voltage has dropped from 7% to 4%, based solely on mitigation of the 5th and 7th harmonics. The fact that the THDu is below 5% ensures stable and reliable operation of equipment and reduced downtime. 

The customer’s choice of supplier and solution came after AiP had successfully demonstrated its expertise, dedication and focus on active harmonic filters, as well as the added value that Comsys’s Active Dynamic Filtering (ADF) technology brings. ADF features such as web server (dashboard), modular concept, user-friendliness, Multimaster mode, clear answers about the warranty and maintenance costs were highly appreciated.

This investment is important because Vetropack Straža expects further technological development, primarily in the form of furnace 63 overhaul, which is due in 2024. With the installation of active filters, we anticipate enhanced workplace safety for our employees, reduced downtime, decreased production losses, and more efficient operation of machinery. Although this practice is already widespread in Europe, within the Vetropack group, we were the pioneers in adopting active filter technology.

Franjo Čoh

Project manager, Vetropack Straža

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