1. Introduction
The food industry of Ukraine operates under strict requirements for the continuity of production cycles, sanitary standards and energy efficiency. Factories for processing milk, production of beverages and confectionery products operate according to continuous flow schemes. Any stoppage of the technological line due to the failure of switching equipment leads to significant financial losses and the risk of spoilage of raw materials.
Control of electric motors of conveyors, mixers, pumps and packaging machines is based on reliable starters and relays. Auxiliary contact blocks, such as the Telemecanique LA1KN31, play a critical role in control systems, providing interlock, indication and communication signals between the various automation links. The safety of the entire technological process depends on their trouble-free operation in accordance with the requirements of EN ISO 13849-1 regarding the safety of machines and mechanisms.
2. Critical components in control systems
The main item under consideration is the Telemecanique LA1KN31 auxiliary contact block. This component is designed to be mounted on the TeSys K series mini contactors. The 3NO + 1NC contact configuration allows multiple control and signaling circuits to be controlled simultaneously.
Technical characteristics of LA1KN31:
- Rated operating voltage: up to 690 V alternating current (AC)
- Thermal current (Ith): 10 A
- Switching wear resistance: more than 1 million cycles
- Degree of protection: IP20 according to IEC 60529
- Certification: CE, UkrSEPRO
In the food sector, the LA1KN31 works as part of complex control panels alongside other important components:
- TeSys K power contactors (for example, LC1K09010P7) — for direct switching of small and medium power drives (from 0.37 kW to 5.5 kW).
- Thermal overload relays (for example, LR2K03) — protection of electric motors against phase interruption and overloading when mechanisms are jammed (calibration according to IEC 60947-4-1).
- Inductive position sensors - monitoring the presence and position of moving parts of conveyors.
- Programmable relays (PLC) — processing of signals from auxiliary contacts to implement blocking algorithms.
3. Typical enterprise layout and process
A typical soft drink or dairy plant includes several processing areas. Consider the path of the product and the location of the electrical equipment:
- Raw material reception and preparation area: Pumps for pumping liquids operate at pressures up to 6 bar and temperatures from +4 °C to +85 °C. Pump station control cabinets contain starters with LA1KN31 contacts to implement dry run logic and redundancy.
- Heat treatment zone (pasteurization): Plate heat exchangers require precise regulation of flows. Temperature regimes reach +95 °C inside the technological circuits, while the environment in the sink (CIP sink) is characterized by high humidity (up to 95%) and the use of caustic cleaning solutions (NaOH, HNO3).
- Botting and packaging area: High-speed rotary lines process up to 24,000 bottles per hour. Here, electromagnetic clutches and drives are controlled through switching devices with a frequency of up to 1200 cycles per hour.
4. Failure modes and impact on downtime
Operating conditions in food processing plants are aggressive due to daily high-pressure cleaning procedures (CIP/COP processes). The main reasons for the failure of auxiliary contacts are:
- Oxidation of contact surfaces due to penetration of moisture and cleaning chemicals (violation of IP54/IP65 control cabinet tightness).
- Mechanical wear of plastic retainers and pushers due to high switching frequency (on bottling lines).
- Loss of spring elasticity of the contact group due to vibrations from working pumps and separators.
Analysis of losses from downtime:
For an average Ukrainian beverage bottling plant, the cost of one hour of unscheduled line downtime ranges from €3,500 to €9,000. This amount includes the loss of productivity, the cost of re-sterilizing the line after an emergency restart, and the labor costs of operators and adjusters. If the failure of the LA1KN31 contact stops the packaging line for 3 hours during peak load, the total loss to the enterprise exceeds €20,000, which is hundreds of times the cost of the component itself.
5. Maintenance strategies: preventive versus predictive
Effective reliability management (Reliability-Centered Maintenance) in the food industry requires a combination of approaches:
| Criterion | Preventive maintenance (PM) | Predictive Maintenance (PdM) |
|---|---|---|
| Approach | Scheduled replacement based on performance (for example, every 12 months). | Моніторинг стану (тепловізор, аналіз контактного опору). |
| Advantages | Reducing the risk of sudden outages during peak demand seasons. | Maximum use of part resources, minimization of costs. |
| Disadvantages | The possibility of replacing serviceable components; spending staff time. | Requires investments in diagnostic equipment and training of specialists. |
| Recommendation for LA1KN31 | A must for primary processing lines with high humidity. | Suitable for centralized control switchboards (MCC). |
6. An example from practice: elimination of an emergency situation
Incident: At a milk processing plant in Central Ukraine, the line for packing ultra-pasteurized milk into Tetra Pak bags was stopped. The alarm system has detected a blocking error of the forming device.
Diagnostics: The chief engineer found melting of the contactor body and failure of the auxiliary unit LA1KN31. The reason was the vibration from the welding drive, which led to vibration wear of the contacts, an increase in transient resistance and local overheating to a temperature above +110 °C (at a norm of up to +55 °C of the environment).
Solution: Replacement of the contactor assembly with auxiliary unit LA1KN31 according to the technical regulations ISO 60947. Additionally, all screw clamps were tightened with a dynamometric tool (tightening torque 1.3 N·m) and vibration-isolating gaskets were installed under the mounting panel. The idle time was 45 minutes. To prevent similar incidents in the future, the supply department has formed an emergency stock of components.
7. Spare parts inventory management (MRO Procurement)
To ensure the uninterrupted operation of Ukrainian factories, the spare parts warehouse management strategy should be based on the criticality of the equipment:
- Minimum safety stock (Safety Stock): For components such as the Telemecanique LA1KN31 and associated TeSys K relays, the company should always have at least 3-5 units in stock for each critical production line.
- Abstract and Cataloging: All parts must have clear factory numbers and be entered into the accounting system (ERP/EAM) with cross-codes of counterparts to avoid downtime due to waiting for specific brands.
- Supply logistics: Cooperation with verified suppliers of industrial components allows to reduce the time of delivery of critical items to Ukraine to a minimum. A complete list of compatible starter control equipment is available in the UNITEC-D E-Catalog.
8. Conclusion
The trouble-free operation of control systems in food processing enterprises depends on every small detail, including auxiliary contacts. The use of certified components, such as the Telemecanique LA1KN31, combined with proper installation and compliance with maintenance regulations, reduces the risk of emergency stops by 70-85%. For prompt selection of original industrial components and ensuring the continuity of production processes, contact the UNITEC-D E-Catalog.
9. Normative references and standards
- EN 60947-4-1: Distribution and control equipment is low voltage. Part 4-1: Contactors and motor starters.
- EN ISO 13849-1: Safety of machines and mechanisms. Management systems related to safety.
- IEC 60529: Degrees of protection provided by enclosures (IP Code).
- DSTU EN 60204-1: Machine Safety. Electrical equipment of industrial machines.
