Device and a method for protecting a link in a medium, high, or very high voltage electrical network

A device for detecting a fault in a medium, high, or very high voltage electrical network, including at least one medium, high, or very high voltage link, the device comprising:

• connection means for direct connection to a power supply, to current and voltage transformers, and to trip circuits disposed on the link, via analog links;
• means for continuously measuring current and voltage delivered by the current and voltage transformers;
• analog to digital conversion means connected to a central processor unit, via a digital link, which central processor unit monitors the current and voltage delivered by the current and voltage transformers;
• means for controlling the trip circuits;
• means for testing operation by injecting current and voltage;
• a base part including a direct connection via analog links to the supply voltage, to the current and voltage transformers, and to the trip circuits;
• an active part, for performing the analog to digital conversion, including at least one socket and being adapted to be inserted in the base part;
• and
• a test part for enabling current and voltage to be injected and configured to be inserted in a socket of the active part.

A method of detecting a fault in a medium, high, or very high voltage electrical network, including at least one medium, high, or very high voltage link, by a device including:

• connection means for direct connection to a power supply, to current and voltage transformers, and to trip circuits disposed on such a link, via analog links;
• means for continuously measuring current and voltage delivered by the current and voltage transformers;
• analog to digital conversion means connected to a central processor unit, via a digital link, which central processor unit monitors the current and voltage delivered by the current and voltage transformers;
• means for controlling the trip circuits;
• and
• means for testing operation by injecting current and voltage;
• the means for direct connection and the analog to digital conversion means being inserted one into the other, the method comprising:
• withdrawing a means for direct connection and an analog to digital conversion means from each other, such that the trip circuits are first disconnected, the current transformer circuits being subsequently short-circuited and disconnected at a same time as the voltage transformer circuits;
• and
• testing by secondary injection of current and voltage after insertion of a test part into the analog to digital conversion means, so as to test them without activating the trip circuits.