Method and device for protecting an autotransformer for an aircraft

A device for protecting a multi-phase autotransformer for an aircraft, provided with a monitoring and control unit configured to:

• receive at least one value of current input into a first phase of the autotransformer, at least one value of current output from the first phase, at least one value of current input into a second phase of the autotransformer and at least one value of current output from the second phase;
• determine, at least as a function of the values of current input into and output from the first phase and of the values of current input into and output from the second phase, at least one value of current representative of an operation of the first phase and at least one value of current representative of an operation of the second phase;
• determine, at least as a function of the values of current representative of the operation of the first and second phases, at least one value representative of a homopolar current flowing in the first phase;
• compare, in a first comparison, the value representative of the homopolar current flowing in the first phase with a first predetermined threshold value;
• control the values of current input into the phases of the autotransformer as a function of the first comparison.