APPARATUS AND INSTRUMENTS FOR CONDUCTING, SWITCHING, CONVERTING, STORING, CONTROLLING AND CHECKING ELECTRICITY, IN PARTICULAR FOR MEDIUM-VOLTAGE DC AND AC LINKS, NAMELY, ELECTRICAL POWER DISTRIBUTION UNITS, ELECTRICAL CONDUCTORS, ELECTRICAL COUPLERS, ELECTRICAL CONNECTORS, ELECTRICAL SWITCHES, ELECTRIC CONVERTERS, CURRENT CONVERTERS, ELECTRIC CONTROLLERS FOR USE WITH POWER CONVERTERS, ELECTRICAL CONTROLLERS, VOLTAGE REGULATORS, VOLTAGE STABILIZERS, AND VOLTAGE MONITORING MODULE