Food packaging line: targeted UPS protection for the critical loads only

1. The facility profile

The client is a modern industrial food production and packaging plant. The production line runs around the clock and includes an automated multi-lane filling, heat-sealing and labeling process, with an indicative capacity of 1,200–1,500 packs per hour.

2. The challenge: voltage sags and unpredictable outages on the production line

Repeated voltage sags and momentary interruptions lasting roughly 100–300 ms had been recorded on the facility's power supply. Although these events were brief, they were enough to affect sensitive electronic loads on the line, such as PLCs, drives / motion inverters, HMIs and sealing / labeling control systems.

Such events may originate either in the utility grid or in dynamic loads inside or near the facility. For the client, the critical issue was not the cause of each event, but its impact on the production line and the time needed to bring the line back to normal operation.

The impact on production was significant:

• Abrupt line stoppage: Even a momentary voltage sag could cause a fault or reboot in the PLCs/HMIs and trip the inverters, causing loss of synchronization and an abrupt stop of the line.
• Risk of damage to the sealing system: In an abrupt stop, the hot sealing jaws could remain in contact with the plastic film, melting the material, producing smoke, requiring manual cleaning and possibly damaging heating elements or temperature sensors.
• Downtime and restart costs: Although the voltage sag lasted only 100–300 ms, the abrupt trip of the line could halt the process at a critical point in the sealing cycle. In such cases, the sealing section had to be cleaned manually, heating elements and sensors checked, materials re-threaded, the automation reset and a test restart run before the line could return to normal production. Total recovery time could reach up to 4 hours, depending on the point in the cycle at which the line stopped.

3. The selective critical-load supply study

Tescom Hellas's technical approach was not based on backing up the entire production line with a UPS, as such a solution would have been significantly more expensive.

Instead, a selective critical-load supply study was carried out. The aim was to support only the subsystems essential for process control, avoiding an abrupt shutdown, protecting the sealing system and allowing the cycle to be completed safely or the line to be stopped in a controlled way.

This way, even during a voltage sag or a short outage, the line does not stop abruptly. The critical systems stay up, giving time to complete the cycle safely or pause the process in a controlled way.

The loads selected for UPS support were the following:

The critical heat-sealing section was not selected to keep full production running on the UPS, but to keep the sealing process under control during a voltage sag or short outage. This reduces the risk of an abrupt stop at a critical point in the cycle and gives time to complete the cycle safely or pause the line in a controlled way.

Loads were selected according to their operational importance to the line. Large loads that were not critical for this selective supply were excluded, such as the central air compressor, auxiliary motors and other loads not needed to safely complete the cycle or stop the process in a controlled way.

4. Sizing & choosing the solution

Based on the critical load inventory, the client's requirement was:

• Critical load power: 43.0 kW / 46.5 kVA
• Required runtime: 15 minutes

Tescom's technical proposal:

The recommended solution was a three-phase Online Double-Conversion UPS, the Tescom TEOS 400, rated at 60 kVA, with a built-in 20 A charger.

Why a 60 kVA UPS?

Safety margin (headroom):
With the load at 46.5 kVA, the UPS runs at about 77.5% of its rated apparent power. This leaves a significant safety margin, so the system does not run at its limit and can better cope with the demands of an industrial environment.

Dynamic load behavior:
The extra power headroom covers momentary peaks, transients and the resynchronization of critical inverter-driven motion, without the UPS running close to its limit or transferring to bypass.

Future expansion of critical loads:
Choosing 60 kVA also leaves reasonable headroom for adding small critical loads in the future, without requiring an immediate upgrade of the UPS solution.

5. The batteries and the safety margin

To achieve the required 15 minutes of runtime for a 43 kW critical load, taking into account an inverter efficiency of 0.95, an external battery cabinet was designed with extra runtime margin.

The battery bank includes:

• 80 batteries, 12 V / 38 Ah
• Configuration: 2 parallel strings of 40 batteries

Based on the facility's critical load and this battery configuration, the estimated runtime of the solution was calculated at about 19 minutes, meeting the client's requirement for at least 15 minutes of support.

This runtime provides enough margin for the line to stay under control during voltage sags or short outages, or until the generator set (genset) has fully taken over the critical loads. If utility power does not return or the genset does not take over in time, the available time allows the cycle to be completed safely or the process to be paused in a controlled way.

This choice provides an additional safety margin under real operating conditions, taking into account factors such as room temperature, normal battery aging and possible small future additions of critical loads.

6. Results & financial benefit

According to the European Power Quality Survey, a pan-European survey carried out under the Leonardo Power Quality Initiative / Leonardo Energy and covering industrial facilities in 8 European countries and 16 different sectors, the annual cost of power quality problems can reach up to 4% of the annual turnover of a production facility. The same survey estimates that total losses for European industry exceed €150 billion per year.

These problems include voltage sags, micro-interruptions, harmonics, transient disturbances and other deviations that can affect sensitive industrial equipment, automation and production lines.

For a mid-sized manufacturer with an annual turnover of €5,000,000, such as the plant in this case study, this translates into a potential annual financial burden of around €200,000.

In this case study, voltage sags and short outages could cause an abrupt line stop, the need to clean the sealing section, automation restarts, scrapped raw and packaging materials, labor hours for recovery and lost production time.

The UPS solution limits this risk by keeping the line's critical loads running and providing the time needed either to transfer to the generator set (genset) or to carry out a controlled shutdown.

Beyond the direct financial savings, the solution brings greater safety, stability and predictability to the operation of the production line, reducing the risk of unplanned shutdowns and helping the facility maintain a more controlled and reliable production process.