Increasing long belt-conveyors availability by using fault-resilient medium voltage AC drives: Part II — Reliability and maintenance assessment

In the mining industry the profitability goals are often linked to the long belt-conveyors availability. Since the use of the medium voltage variable frequency drives (MV-VFD) in conveying applications is essential to meet various technical requirements, the conveyor service continuity depends on the drive system availability. Although there are at least three established technologies commercially available, the drive solution using three-level (3L) IGCT-based, neutral point clamped (NPC) converters is clearly the most popular for higher powers. In the early parts of this work [1] and [2], it was shown how to design a fault-resilient 3L-NPC IGCT-based converter, in this second part, the reliability, availability and maintenance aspects of MV-VFD are discussed with focus on the benefits provided by the fault-resilient design. The stock forecasting for spare parts considering a multidrive common dc bus used in a real downhill conveyor is performed and analyzed under catastrophic protection failure standpoint.