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Polyethylene blown film, Kotoriba

Polyethylene blown film, Kotoriba

Industry: Packaging
Customer: Muraplast
Local partner: Automatika i procesi
Timeline: Nov 2017


MURAPLAST is the leading and most modern producer of polyethylene blown film in Croatia and Southeastern Europe.

  • Operates with an annual production capacity of 20,000 tons

  • Distributes operations over 5 production halls  

  • Uses more than 12,500 m² of production and storage capacity 

  • Employs more than 230 people 

The main product Muraplast offers is extruded polyethylene tubular blow film mainly used for the packaging of food and beverages. Muraplast also produces industrial bags, pallet covers, sacks and shopping bags with different carrying handles (Soft loop Handle bags, Patch Handle Bag, Die Cut Handle Bag), and other products of similar use.

With their production ongoing 24 hours a day, 7 days a week, just 1 problem in production can lead to 2 days out of operation. With the opportunity of a developing market, Muraplast was constantly upgrading their production lines with machines equipped with variable frequency drives. At one point, it became an issue for the Power Factor Correction Units.


In any business, unplanned stops are a nightmare. In Muraplast’s case, overheated or burned out inductors on the Power Factor Correction unit led to this scenario, causing serious concern. After the measurement was made according to norm EN 50160, the recommendation from AiP was to lower the 5th and 19th harmonics in order to get the THvD below 5%. While the harmonics were below limits set in EN 50160, they were close enough to the limit to cause concern, with the 5th harmonic identified as the major cause of problems on the Power Factor Correction unit.

Overall, the harmonic distortion presented risks to the viability of the equipment lifetime. But beyond the functionality issues, the worst-case scenario would be that the whole hall of the production line would burn down, garnering loss of production and significant costs.

Figure 1: Individual harmonics before the installation of the active filter ADF P100
Figure 1: Individual harmonics before the installation of the active filter ADF P100
Figure 2: Total THvD and THiD before the installation of the active filter ADF P100
Figure 2: Total THvD and THiD before the installation of the active filter ADF P100


During commissioning, it was determined that the phase order of the current transformers was incorrect. Of course, not wanting to stop production to change the phase order of the connected current transformers, Sensorless Control was used to circumvent the issue.

"Comsys helped us with technical support and consultations regarding proper installation and implementation of ADF in current schematic diagram."

Milan Stanić


When asked why ADF was chosen by the customer over competing solutions, Automatika i procesi shared, “As a Comsys partner, we explained to the customer every aspect of their production issue and offered multiple solutions. We showed expertise, professionalism and flexibility and the customer has not searched for any other solution.”

Products used in this case:

  • ADF P100-130/480_T-E-----20


After 12 months of working 24/7, Muraplast is pleased to report there are no problems with the Power Factor Correction unit, the THvD is below 4%, and the factory is working normally without any fear of stopping. And, the problem with the inductor overheating has been completely solved.

It’s no surprise then that Muraplast is very satisfied with the whole solution, especially with the reliability, and would like to continue implementing ADF solutions through its production halls.