Abstract: The present invention is applicable for inverter-type power plants where the electric distribution line is used as stand-by unit. The present invention is composed of a ballast impedance and an electric mesh including an energizing circuit of a first section suitable for insulating a power plant from the distribution line; contacts of a second section which are monitored by a supervisory control circuit of the power plant; and an electric probe for making available a voltage or a current measurement when current flows through the distribution line.

Abstract: A power system includes as many synchronizing units as the number of the power units. Each synchronizing unit has been designed to receive an activation signal at its input and to be connected to the other units through of a first and a second discs. Each synchronizing unit delivers to its output a synchronizing clock signal for the respective power units. The first synchronizing unit which receives the activation signal is qualified as the master unit. This master unit applies a predetermined polarity to the first bus and a clock signal to the second bus in order to synchronize the other units in response to the detection of the polarity on the first bus, the other units are characterized as slave unit.

Abstract: Modular supply systems usually include a plurality of n elementary power units, connected in parallel to each other. Control unit (RV) and selective breakaway unit (DS) are associated with each elementary power unit. The monitoring circuit (CP) includes a first device (PM) which calculates the entity of the deviation (E) between a signal (Iu.sub.i) that is proportional to the current supplied by the relevant power unit (UA.sub.i) and a signal (I.sub.med) that is proportional to the average value of the currents supplied by the n power units. Also, a second device (SM) algebraically sums the deviation (E) to a signal (Vu.sub.i) that is proportional to the voltage available on the output of the relevant power unit. The signal (Vc) that is available on the output of the second device is delivered to the control unit (RV) and the selective breakaway unit (DS).