A power distribution system comprising: a plurality of power distribution units each having a field replaceable master management module ; and each of the power distribution units further having at least one set of socket management modules configured to manage a power output, wherein the master management module connects to each of the corresponding socket management modules for monitoring a power output state of each of the socket management modules , and for controlling a switching state of the power output of each of the socket management modules ; wherein the master management module of each of the power distribution units further comprises an incoming port for connecting to an external device or cascading a first other power distribution unit and an outgoing port for cascading a second other power distribution unit; each power distribution unit further comprising a sensor module that connects to the master management module of the corresponding power distribution unit for obtaining surrounding environmental parameters of the power distribution unit including temperature or humidity values; wherein the plurality of power distribution units is cascaded by serial and /or controller area network BUS, CAN-BUS, the cascading of the plurality of power distribution units through individual master management modules being in the form of a daisy-chain; wherein only one master management module is directly connected to said external device; and the system is configured such that data of other master management modules are transmitted to the master management module that is directly connected to said external device so that the data is sent to said external device; and wherein each of the master management modules includes a LCD monitor for displaying the temperature or humidity values gathered by said sensor module . a plurality of power distribution units each having a field replaceable master management module ; and each of the power distribution units further having at least one set of socket management modules configured to manage a power output, wherein the master management module connects to each of the corresponding socket management modules for monitoring a power output state of each of the socket management modules , and for controlling a switching state of the power output of each of the socket management modules ; wherein the master management module of each of the power distribution units further comprises an incoming port for connecting to an external device or cascading a first other power distribution unit and an outgoing port for cascading a second other power distribution unit; each power distribution unit further comprising a sensor module that connects to the master management module of the corresponding power distribution unit for obtaining surrounding environmental parameters of the power distribution unit including temperature or humidity values; wherein the plurality of power distribution units is cascaded by serial and /or controller area network BUS, CAN-BUS, the cascading of the plurality of power distribution units through individual master management modules being in the form of a daisy-chain; wherein only one master management module is directly connected to said external device; and the system is configured such that data of other master management modules are transmitted to the master management module that is directly connected to said external device so that the data is sent to said external device; and wherein each of the master management modules includes a LCD monitor for displaying the temperature or humidity values gathered by said sensor module . <EOS>