Moscow Central Diameters (MCD) is a system of city train services on existing commuter rail lines in Moscow and Moscow Oblast, Russia, which began operation in 2019. As an important livelihood project, MCD requires a long-term and reliable power system. However, due to the perennial train in and out of the light rail building will produce dust, it’s easy to lead to the electrical equipment inside full of ash, resulting in short circuit failure of internal components and other faults. With internal isolation transformer and the design of three proofing properties for preventing from dusk, smog and salt, Kehua FR-UK33 UPS has proved its stability, well adaptation and high efficiency especially for track road characteristic and usage scenario.