Hi, I got a problem and seeking for help, could anyone do me a favor. The power supply of network data centre is supplied by a UPS. The UPS’s output connects to 2 nos. of 800A MCCB individually. And the circuits are protected by: ( Form >> to ) A) 800A MCCB >> 100A MCCB >> 100A AI switch >> ( circuit 1 & 2 ) 1) 63A Type C MCB >> 63A AI switch >> 32A RCBO >> Power socket 2) 63A Type B MCB >> Floor box (40A RCCB + Power socket) B) 800A MCCB >> 100A MCCB >> 100A AI switch >> 63A Type B MCB >> Floor box (40A RCCB + Power socket) The case is that, a fault occurred at data server that supply by the power socket of circuit A(1). The 32A RCBO was tripped. When I tried to reset the RCBO, it tripped again immediately. At the mean time, an unpredictable scenario was happened. Some RCCB (around 6 nos.) at circuit A(2) and circuit B were tripped at the same time immediately. That caused around 7 nos. of servers were downed. Could anyone do me a favor to give a hint? Thanks you so much.