Electrical link comprising an electrical protection system

1. An electrical link comprising:

a protective sheath surrounding conductors;

each of the conductors configured to link a direct voltage source to a respective user equipment item, wherein each of the conductors is covered by a respective insulating jacket;

an electrical protection system comprising:

a conductive sheath around the insulating jacket for each of the conductors,

for each of the conductors, a circuit breaker in series with the conductor and configured to interrupt current in the conductor when the circuit breaker is activated;

for each of the conductors, a direct current generator connectable to the conductive sheath and configured to apply a non-zero current (Ig) to the conductive sheath on reception of an activation signal; and

for each of the conductors, leakage current detection assembly connected to the conductive sheath and to the circuit breaker for the conductor;

a sequencer supplying, in succession, the activation signal to the current generators;

for each of the conductors, the leakage current detection assembly is configured to measure a current (Ir) passing through the conductive sheath and compare a voltage (Ur) proportional to said current (Ir) to a first range of values and to a second range of values, the detection assembly activating the circuit breaker:

if the voltage (Ur) is outside of the first range of values while the current generator generates a non-zero current (Ig); and

if the voltage (Ur) is outside of the second range of values while the current generator generates a zero current.

2. The electrical link according to claim 1 , wherein a minimum value of the first range of values is greater than a maximum value of the second range of values.

3. The electrical link according to claim 1 , wherein the sequencer comprises outputs (Q 1 , Q 2 ) in which each of the outputs is dedicated to a respective one of the conductors, and is connected to the current generator and to the detection assembly associated with said conductor.

4. The electrical link according to claim 1 , wherein each of the detection assemblies includes:

a resistor having a first terminal and a second terminal, the first terminal resistor being connected to the conductive sheath and the second terminal being connected to a ground at its second terminal; and

a comparison module connected to the first terminal of the resistor via an electrical link, and configured to compare the value of the voltage (Ur) to the first range of voltage values and to the second range of voltage values.

5. The electrical link according to claim 4 , wherein the comparison module comprises a first window comparator for comparing the value of the voltage (Ur) to the first range of values and a second window comparator for comparing the value of the voltage (Ur) to the second range of values.

6. An electric protection system for a conductor in an electrical link in an aircraft, wherein the electrical link includes multiple conductors, and wherein the electric protection system includes:

a conductive sheath surrounding the conductor;

an insulating jacket surrounding the conductor and surrounded by the conductive sheath, wherein the insulating jacket isolates the conductive sheath from the conductor;

a circuit breaker in series with the conductor and configured to interrupt current in the conductor;

a direct current generator electrically connected to the conductive sheath and configured to generate a non-zero current in response to an activation signal;

a sequencer configured to cyclically and alternatively apply the non-zero current and a zero-voltage to the conductive sheath; and

a leakage current detection circuit electrically connected to the conductive sheath and to the circuit breaker;

wherein the leakage current detection device is configured to measure a current (Ir) flowing through the conductive sheath and compare a voltage (Ur) proportional to the current (Ir) to a first range of voltage values and to a second range of voltage values,

wherein the leakage detection assembly activates the circuit breaker to interrupt the current in the conductor:

if the voltage (Ur) is outside of the first range of voltage values while the current generator generates a non-zero current; and

if the voltage (Ur) is outside of the second range of voltage values while the current generator generates a zero current.

7. The electrical protective system of claim 6 , wherein a minimum absolute value of the first range of voltage values is greater than a maximum value of the second range of voltage values.

8. The electrical protective system of claim 6 , wherein the sequencer comprises outputs (Q 1 , Q 2 ) in which each of the outputs connected to the current generator and to the leakage current detection circuit associated with said conductor.

9. The electrical protective system of claim 6 , wherein the leakage current detection circuit includes:

a resistor having a first terminal connected to the conductive sheath and a second terminal connected to a ground; and

a comparator electrically connected to the first terminal of the resistor and configured to compare the value of the voltage (Ur) to the first range of voltage values and to the second range of voltage values.

10. The electrical protective system of claim 9 , wherein the comparison module comprises a first window comparator for comparing the value of the voltage in the detection line to the first range of values and a second window comparator for comparing the value of the voltage in the detection line to the second range of values.

11. A method to electrically protect conductors in an electrical link in an aircraft, the method comprising:

providing electrical power from a power voltage in the aircraft through the electrical link to electrical powered devices in the aircraft, wherein a first device of the electrical powered devices receives the electrical power via a first conductor in the electrical link and a second device of the electrically powered devices receives the electrical power via a second conductor;

alternating between applying a zero value voltage and a non-zero direct current voltage to the first conductive sheath;

alternating between applying a zero value voltage and a non-zero direct current voltage to the second conductive sheath;

measuring electrical voltages of a first conductive sheath on the first conductor and monitoring electrical voltage levels of a second conductive sheath on the second conductor, wherein the first conductive sheath is electrically isolated from the first conductor by an insulating jacket sandwiched between the first conductive sheath and the first conductor, and the second conductive sheath is electrically isolated from the second conductor by an insulating jacket sandwiched between the second conductive sheath and the second conductor;

interrupting electrical current in the first conductor, if the measured electrical voltage of the first conductive sheath exceeds a low range of electrical voltage values while the zero value is applied to the first conductive sheath;

interrupting electrical current in the first conductor, if the measured electrical voltage of the first conductive sheath exceeds a high range of electrical voltage values while the non-zero direct current voltage is applied to the first conductive sheath, wherein the second range does not overlap with the first range;

interrupting electrical current in the second conductor, if the measured electrical voltage of the second conductive sheath exceeds the low range of electrical voltage values while the zero value is applied to the second conductive sheath;

interrupting electrical current in the second conductor, if the measured electrical voltage of the second conductive sheath exceeds the high range of electrical voltage values while the non-zero direct current voltage is applied to the second conductive sheath.

12. The method of claim 11 wherein the zero voltage is a voltage at a ground in the aircraft, and the measured electrical voltage is measured with respect to the ground.

13. The method of claim 11 wherein the non-zero direct current voltage is alternatively applied to the first and second conductors.

14. The method of claim 11 wherein the high range includes the non-zero direct voltage, and the low range includes the zero value.

15. The method of claim 11 wherein each of the interruption of the electrical current is delayed by a certain period after a transition between the zero value and the non-zero direct current and the determination of each of the interruptions is made after the certain period.