Abstract: An apparatus for monitoring current levels at adjacent zones along an a.c. transmission line is provided by current transformers at said zones, the secondaries of the transformers being connected in a series circuit such that currents induced in the secondaries are all in the same direction in said series circuit. Resistors are connected between a common connection of the series circuit and respective interconnections between the transformer secondaries. Devices are provided for monitoring the voltages across the resistors.

Abstract: A generator set includes a main generator, a permanent magnet pilot alternator, a rectifier assembly connecting the pilot alternator output to first and second supply rails, a relay having a contact, and a regulator for the main generator having a semi-conductor output element, the output element, the field winding and the contact being connected in series between the first and second supply rails. A power supply circuit is transformer coupled to the pilot alternator and provides a stabilized power supply both for the regulator and the relay, such power supply circuit having an earthed terminal. A resistor is connected between the second supply rail and the earth terminal, so as to limit fault current in the event of an earth fault in the connection between the contact and the field winding.