A compressor with a built-in electric motor has a compression mechanism and the built-in electric motor which are housed in a container. Each transpose box can include a number of connectors and a meshing useful for implementing a specific network topology. The motor control apparatus then computes a voltage command value in accordance with the current deviation accumulated value and controls the switching timing of the switching element based on the voltage command value. If \u0394SA3=|SA3\u2212SA3|, \u0394SA5=|SA5\u2212SA5|, the following expression is satisfied: 0. This protection switching is an extensible operation, and typically may include, but is not limited to switching traffic to a backup facility from a facility corresponding to the condition and switching traffic to a backup component from a component corresponding to the condition. 2 to 3 weight % of the slag cement; and a source of calcium sulfate in such a proportion that the content of calcium sulfate, relative to the weight of the slag cement, is from 2 to 7%.