A method of producing a laminated iron core by punching and laminating rotor and stator core pieces. A shell-and-tube reactor in the system is adapted to circulate a heat medium having a solid point in the range of 50-250\xb0 C. In another example, multiple actuators are utilized with each actuator being associated with a separate motor driven pump in communication with a common controller. The PMU also includes a signal protection circuit coupled to an input of the gain control block. The snap fit mechanism comprises projections formed on one of the components and recesses formed on the other of the components, where the projections engage the recesses to maintain the components in a desired position relative to each other against incidental force. A viewer may be provided for displaying data stored in the document repository.