Introduction: why the 2005 conveyor line no longer meets production requirements
Conveyor belts and roller conveyors remain the backbone of continuous production — from cement plants to food processing lines. However, most systems installed before 2010 operate on IE1/IE2 class asynchronous motors, mechanical speed variators and contact limit switches. Such solutions consume 15–25% more electrical energy than modern equivalents and do not provide diagnostic data for predictive maintenance.
The drivers of modernization are three factors. First, the EU Ecodesign Regulation 2019/1781, which sets the minimum efficiency class IE3 for motors with power from 0.75 to 1000 kW, applies also to equipment supplied to Ukraine through European OEM supply chains. Second, mandatory energy audits of industrial enterprises according to DSTU ISO 50001:2014 reveal conveyor systems as a typical area of unjustified losses — up to 12% of the total energy consumption of the raw material transportation section. Third, worn-out bearing units and the absence of vibration monitoring are the direct cause of unplanned stoppages, which, according to our statistics, account for 60–70% of all conveyor line breakdowns in 40+ projects in Ukraine.
In this article we consider a technically justified approach to retrofitting: from assessment of the existing equipment condition to calculation of investment return and phased implementation without production stoppage.
1. Legacy System Assessment
Before making a decision on modernization, a technical audit of each node of the conveyor line is required. We use a checklist with 8 criteria that corresponds to the RCM (Reliability Centered Maintenance) methodology according to DSTU EN 60300-3-11.
| Evaluation Criterion | Control Method | Threshold value for replacement |
|---|---|---|
| Engine efficiency class | Passport data, measurements of cos φ | Below IE3 |
| Condition of bearing units | Vibration analysis (ISO 10816-3), thermography | Vibration velocity > 4,5 mm/s RMS |
| Positioning accuracy of the belt | Analysis of end switches vs. encoders | Error > 5 mm |
| Presence of diagnostic interface | Connection protocol check with PLC | Missing (only relay logic) |
| Mean Time Between Failures (MTBF) | CMMS data over 3 years | < 4000 year |
| Specific energy consumption, kW·h/t | Metering unit on the drive station | Above the industry benchmark by 15%+ |
| Availability of recovery on inclined sections | Drive scheme, type of braking resistor | Energy dissipation in the resistor |
| Availability of Spare Parts | Manufacturer's Catalog, EOL Term | The manufacturer has discontinued support |
Important: audit results should be documented in a format compatible with the company's internal asset register, to justify capital expenditures to the finance department.
2. Modern Alternatives: Technology Comparison
Key modernization directions — modular motor-reducers with variable frequency (VFD), intelligent condition sensors (vibration, temperature, load) and regenerative drive stations.
| Parameter | Old system | Modern solution |
|---|---|---|
| Engine type | Asynchronous IE1/IE2, fixed speed | IE3/IE4 with vector frequency converter |
| Drive efficiency | 82–86% | 93–96% |
| Speed Control | Mechanical variator or single-speed | Smooth regulation 0–100% through VFD |
| Diagnosis | Not available, visual inspection | Wireless IO-Link sensors, data transmission in SCADA/MES |
| Bearing units | Open or with standard sealing, reconditioning every 500 hours | SKF 6022-2RS1 — sealed bearings with double rubber sealing 2RS1, grease life up to 20 000 hours under moderate loads |
| Energy balance on inclined sections | Braking resistor dissipates energy as heat | Regenerative converter returns up to 30% of braking energy back to the grid |
| MTBF | 3500–4500 year | 9000–12000 years according to the manufacturer's data of drives |
| Compliance with standards | Does not comply with Ecodesign 2019/1781 | CE, UkrSEPRO, IE3 compliance according to DSTU EN 60034-30-1 |
Roller bearing SKF 6022-2RS1 (size 110×170×28 mm, dynamic load Cr = 60,5 kN) — a typical example of replacing open bearings on drive drums of medium and heavy class. Double sealing 2RS1 reduces the need for lubrication by 70% compared to open design, which is critical for conveyors in dusty workshops of cement and mining enterprises.
3. Calculation of Return on Investment (ROI)
We provide a real calculation for a typical conveyor of 120 m length, with a drive power of 55 kW, operating in three shifts (6000 hours/year) at a medium-sized metallurgical plant.
Input data
- Tariff for industrial electricity (Ukraine, 2024): 4,8 грн/кВт·год
- Hourly rate of maintenance personnel with overhead costs: 350 грн/год
- Production losses during downtime: 18 000 грн/год
- Present power consumption (IE2, without VFD): 55 kW × 0,85 load = 46,75 kW·h
- Post-modernization consumption (IE3 + VFD, speed optimization): 38,2 kW·h (reduction 18,3%)
Cost Savings Calculation
| Indicator | Before modernization | After modernization | Savings per year |
|---|---|---|---|
| Annual consumption, kW·h | 280 500 | 229 200 | 51 300 kW·h |
| Electricity costs, UAH | 1 346 400 | 1 100 160 | 246 240 грн |
| Unplanned downtime, hours/year | 42 | 12 | 30 years |
| Losses from stoppages, UAH | 756 000 | 216 000 | 540 000 грн |
| Costs for MRO (spare parts + labor), UAH/year | 410 000 | 195 000 | 215 000 грн |
Total annual saving: 246 240 + 540 000 + 215 000 = 1 001 240 грн.
Capital expenditures for retrofitting one conveyor (motor-reducer with VFD, SKF 6022-2RS1 bearing set, IO-Link vibration sensors, installation): approximately 980 000–1 150 000 UAH depending on the configuration of the recuperative module.
Payback period: 11–14 months. For a line with 6–8 conveyors, typical for the raw material transportation section on a cement plant, the total effect exceeds 6 million UAH per year with capital investments close to 7 million UAH.
4. Implementation Roadmap
Modernization of the conveyor line without interrupting main production requires a phased approach.
- Phase 1. Planning and Audit (2–3 weeks) — vibration analysis, thermography, data collection from CMMS, preparation of technical specification (TS) in accordance with DSTU EN 61508 regarding functional safety of control systems.
- Фаза 2. Проєктування та закупівля (4–6 тижнів) — підбір мотор-редукторів, узгодження специфікацій підшипників (SKF 6022-2RS1 та аналоги для інших вузлів), замовлення через UNITEC-D E-Catalog з підтвердженням термінів поставки 3–5 тижнів для складських позицій.
- Phase 3. Pilot Section (1 week) — modernization of one conveyor outside the critical production path for validating the solution in real conditions.
- Phase 4. Step-by-step installation (according to the schedule of planned stoppages) — replacement of drive stations during planned technological stoppages lasting 8–12 hours per unit of equipment.
- Фаза 5. Пусконалагодження та навчання персоналу (2 тижні) — калібрування VFD, налаштування порогів вібромоніторингу, інструктаж змінного персоналу.
- Phase 6. Warranty Support (12 months) — KPI monitoring, regulator speed setpoint adjustment.
5. Technical Challenges During Retrofit
Practical experience in carrying out projects in Ukraine reveals typical problems.
- Misalignment of dimensional tolerances — old bearing support housings often have non-standard tolerances. Solution: use of transition sleeves or complete replacement of the support unit according to DSTU EN ISO 286-2.
- Harmonic distortions in the network from VFD — when several frequency converters are installed on one substation, the THD may exceed 5% (DSTU EN 61000-3-12). Solution: installation of choke filters on the converter input.
- Communication Protocol Compatibility — older PLCs on Modbus RTU do not always support modern IO-Link sensors without a gateway-converter.
- Mechanical resonance of the conveyor frame at change of the rotational frequency of the drive drum — requires checking of the natural frequencies of the structure by modal analysis before final VFD tuning.
- Resistance to Change — is resolved through parallel operation of the old and new interface during the transition period of 2–4 weeks.
6. Case: Modernization of the cement conveying line
Cement plant in Dnipropetrovsk region, conveyor line of 340 m length with three drive stations (2×55 kW, 1×75 kW), year of commissioning — 2008.
| Indicator | Before modernization | After modernization (after 6 months) |
|---|---|---|
| Specific energy consumption, kW·h/t clinker | 1,42 | 1,15 |
| Number of unplanned stops/year | 27 | 6 |
| MTBF of drive units, hours | 3800 | 10 200 |
| Planned bearing inspection time, hours/month | 16 | 4 |
| Lubrication costs for bearings, UAH/year | 85 000 | 22 000 |
Replacement of open bearings with sealed SKF 6022-2RS1 in high dust zone reduced the ingress of abrasive cement dust particles into the lubrication node, which directly influenced the increase of MTBF by 2.7 times.
7. Commissioning and validation
The acceptance of the modernized system is carried out according to the protocol that includes:
- Vibration velocity check at no load and under load (norm according to DSTU ISO 10816-3 — not higher than 2,8 mm/s RMS for new class II equipment).
- Thermographic inspection of bearing units after 72 hours of continuous operation - exceeding 70°C for grease lubrication is considered a deviation.
- Testing of emergency stop and safety functions according to DSTU EN ISO 13849-1 (safety category PLd minimum for conveyor systems).
- Data transmission verification from IO-Link sensors to the supervision system — signal delay not more than 100 ms.
- Control run for 240 hours (10 days) with recording of actual energy consumption for verification against calculated ROI.
Response to objection: "the old system is still working"
The argument "equipment is functioning, why spend money" ignores hidden costs. The calculation of total cost of ownership (TCO) over 5 years for a motor-driven conveyor with IE1 efficiency includes: energy consumption 18–25% above standard, annual repair cost increases of 12–15% due to accumulated bearing degradation, risk of penalty sanctions during audit according to energy efficiency requirements for exporting enterprises in the EU, and lack of data for predictive maintenance, increasing the likelihood of unplanned downtime. In most TCO projects, the cost of the outdated system over 5 years exceeds the cost of full modernization by 40–60%.
Conclusion
Modernization of conveyor systems is not equipment replacement for the sake of replacement, but a technically justified solution with a payback period of 11–14 months per individual conveyor. The combination of IE3/IE4 class drives with VFD, sealed bearings such as SKF 6022-2RS1, and wireless condition sensors allows to reduce energy consumption by 15–20% and increase MTBF by 2–3 times.
UNITEC-D GmbH supplies the entire range of components for retrofitting – from certified SKF bearings to modular drive stations and monitoring systems, with technical documentation supported according to the requirements of CE and UkrSEPRO. Select the necessary components for your modernization project in UNITEC-D E-Catalog.
Sources and Regulatory Documents
- Regulation (EU) 2019/1781 — Ecodesign requirements for electric motors and variable speed drives
- DS TU EN 60034-30-1:2016 — Electric Rotating Machines. Efficiency Classes
- DSSTU ISO 50001:2014 — Energy Management Systems
- DSSTU ISO 10816-3 — Vibration. Assessment of machine condition based on measurements on stationary parts
- DSTU EN 61000-3-12 — Limitation of Current Harmonics
- DSSTU EN ISO 13849-1 — Safety of machinery. Safety-related parts of control systems
- SKF Rolling Bearings Catalogue — Technical Characteristics of Series 6022-2RS1
- UNITEC-D E-Catalog — Specifications of Drive Systems and Components for Conveyor Equipment
