For many years electronic telephone exchanges have been computer controlled, and also supervised by computer-controlled systems. However, up to now the supervision of power supply equipment has not been computer controlled. This trend has now been broken by the recent introduction of two newly developed power supply systems with stored program control of the operation as well as the supervision. The first system, BZD412 for large plants, includes the control system ERICSSON ENERGYMASTER. A version of the power system BZA106 with microprocessor control for small plants is described. The new system is particularly suitable for unmanned exchanges, whose maintenance costs can be drastically reduced with the aid of computer control and centralized supervision.