Introduction: In a significant project, a customer sought a reliable backup power solution for the building lighting load, which comprised fluorescent lights with a low power factor. The customer opted for transformer less Uninterruptible Power Supply (UPS) units, anticipating seamless operation. However, complications arose due to the unsuitability of the UPS units for the specific characteristics of the lighting load. This case study underscores the necessity of having a consultant engineer with UPS system experience to guide the selection process, especially in scenarios where critical load requirements demand precision and reliability.
Background: The project aimed to secure a backup power source for the building lighting load that presented unique challenges—fluorescent lights with a low power factor. The decision to employ transformer less UPS units, designed for various applications but not explicitly for this type of load, proved to be a critical oversight.
Issues Encountered:
- Incompatibility with Fluorescent Lights and Low Power Factor: The UPS units, being transformer less and not tailored for low power factor loads, failed to provide optimal support for the lighting load. This resulted in inefficiencies and compromised performance.
- Continuous Online Operation: The UPS units, configured in an online mode where the load is constantly running on the inverter, subjected the system to prolonged stress, contributing to the premature failure of some units.
- Failure of UPS Units: Several UPS units experienced failures within a few months of operation due to the mismatch between the design specifications and the unique characteristics of the lighting load.
- High Cost and Overlooking a More Suitable Alternative: The selected UPS system, despite being ill-suited for the application, came at a high cost. Additionally, an alternative solution in the form of an Emergency Power Supply (EPS) system, designed to handle low power factor loads, was overlooked.
Role of a Consultant Engineer with UPS System Experience:
- Load and Application Analysis: A consultant engineer with UPS system experience would have conducted a detailed analysis of the specific lighting load characteristics, recognizing the low power factor associated with fluorescent lights.
- Compatibility Assessment: Understanding the nuances of the application, a consultant engineer could have recommended the EPS systems or alternative power solution specifically designed to handle low power factor loads.
- Operational Configuration Guidance: By providing guidance on the operational configuration, a consultant engineer could have suggested adjustments to minimize stress on the UPS units, potentially extending their lifespan.
- Alternative Solution Recommendation: Drawing on experience, a consultant engineer could have recommended an EPS system, which, being line-interactive, offers a more cost-effective and reliable solution for lighting loads with low power factor requirements.
Conclusion: This case study highlights the critical importance of involving a consultant engineer with UPS system experience in the decision-making process for power solutions, particularly in projects with unique load characteristics. The oversight in selecting transformer less UPS units for a lighting load with low power factor led to operational challenges and unnecessary costs. A knowledgeable consultant engineer could have guided the selection process, ensuring the choice of a suitable, reliable, and cost-effective power solution tailored to the specific requirements of the application.
