Protection method and device of an electrical network for aircraft

Patent metadata

Field	Value
Publication number	US-9368957-B2
Application number	US-201314052255-A
Country	US
Kind code	B2
Filing date	Oct 11, 2013
Priority date	Oct 11, 2012
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A method for protecting a bipolar power distribution network supplied with power by an electric power source isolated from an electrical ground of an aircraft. The network includes a resistive protection device configured to be connected to the electrical ground and to the two phases of the network. The method includes the steps of receiving at least one voltage value on at least one of the two phases and/or at least one current value in the electrical ground, comparing the at least one voltage value with a first predetermined threshold value and/or the at least one current value with a second predetermined threshold value and controlling the protection device by changing its resistivity according to the comparison.

First claim

The invention claimed is:

1. A method for protecting an electrical network for aircraft, wherein said network is a bipolar power distribution network, which is supplied with electrical power by an electric power source of said aircraft, said electric power source is isolated from an electrical ground of said aircraft, said bipolar power distribution network comprises two phases and a resistive protection device configured to be connected to said electrical ground of said aircraft and to the two phases of said bipolar power distribution network, wherein said method comprises the steps of:
receiving at least one voltage value on at least one of said two phases of said bipolar power distribution network and at least one current value in said electrical ground of said aircraft;
comparing at least one of
said at least one voltage value with a first predetermined threshold value and
said at least one current value with a second predetermined threshold value;

controlling said protection device by changing its resistivity according to said comparison.

2. The method according to claim 1 , wherein said protection device is provided with a variable resistive system, wherein said method further comprises, prior to said receiving step, a step of controlling said variable resistive system so that said variable resistive system is balanced and has a first predetermined global resistance value.

3. The method according to claim 1 , wherein said protection device is provided with a variable resistive system and said step of controlling said protection device according to said comparison is performed by controlling said variable resistive system so that it is imbalanced and has a second predetermined resistance value and a third predetermined resistance value smaller than said second predetermined resistance value.

4. The method according to claim 2 , wherein said step of controlling said protection device according to said comparison is performed by controlling said variable resistive system so that it is imbalanced and has a second predetermined resistance value and a third predetermined resistance value smaller than said second predetermined resistance value and wherein said variable resistive system is formed by a bridge of variable resistive elements provided with a first resistive element connected to said one phase of said bipolar power distribution network, a second resistive element connected to said other phase of said bipolar power distribution network and separate from said first resistive element, and a midpoint located between said first and second resistive elements and connected to said electrical ground of said aircraft, with said first predetermined global resistance value being representative of a first predetermined resistance value of each of said first and second resistive elements.

5. The method according to claim 4 , wherein said second predetermined resistance value is representative of the resistance value of one of said first and second resistive elements, which is connected to the faulty phase of said bipolar power distribution network, and said third predetermined resistance value is representative of the resistance value of the other of said first and second resistive elements, which is connected to the other non-faulty phase of said bipolar power distribution network.

6. The method according to claim 5 , wherein said second predetermined resistance value is greater or equal to said first predetermined resistance value, and said third predetermined resistance value is gradually decreased.

7. The method according to claim 1 , wherein said first predetermined threshold value is representative of a voltage of said electrical ground of said aircraft and the result of said step of comparing said first predetermined threshold value with said at least one voltage value is representative of the fact that said at least one voltage value is smaller or equal, in absolute value, to said first predetermined threshold value when a fault is present on said one phase of said bipolar power distribution network.

8. The method according to claim 1 , wherein said second predetermined threshold value is representative of a current value in said electrical ground of said aircraft when no fault is present, that is, when it is approximately equal to zero, and the result of said step of comparing said second predetermined threshold value with said at least one current value is representative of the fact that said at least one current value is positive or negative and greater, in absolute value, than said second predetermined threshold value when a fault is present on said one phase of said bipolar power distribution network.

9. The method according to claim 1 , wherein said bipolar power distribution network further comprises at least one power cut-off device and said method further comprises the step of tripping said power cut-off device.

10. A protection device in an electrical network for aircraft, wherein said network is a bipolar power distribution network comprising two phases, which is supplied with electrical power by an electric power source of said aircraft, said electric power source is isolated from an electrical ground of said aircraft, said protection device is resistive, is configured to be connected to said electrical ground of said aircraft and to the two phases of said bipolar power distribution network and comprises a control and operating unit configured for:
receiving at least one of at least one voltage value on at least one of said two phases of said bipolar power distribution network and at least one current value in said electrical ground of said aircraft;
comparing at least one of said at least one voltage value with a first predetermined threshold value and said at least one current value with a second predetermined threshold value;
controlling said protection device by changing a resistivity of said protection device according to said comparison.

11. The device according to claim 10 , wherein the device comprises a variable resistive system and said control and operation unit is configured, before receiving at least one of at least one voltage value and at least one current value, to control said variable resistive system so that it is balanced and has a first predetermined global resistance value.

12. The device according to claim 10 , wherein the device comprises a variable resistive system and said control and operation unit is configured to control said variable resistive system so that it is imbalanced and has a second predetermined resistance value and a third predetermined resistance value smaller than said second predetermined resistance value.

13. The device according to claim 11 , wherein said control and operation unit is configured to control said variable resistive system so that it is imbalanced and has a second predetermined resistance value and a third predetermined resistance value smaller than said second predetermined resistance value and wherein said variable resistive system is formed by a bridge of variable resistive elements provided with a first resistive element connected to said one phase of said bipolar power distribution network, a second resistive element connected to said other phase of said bipolar power distribution network and separate from said first resistive element, and a midpoint located between said first and second resistive elements and connected to said electrical ground of said aircraft, with said first predetermined global resistance value being representative of a first predetermined resistance value of each of said first and second resistive elements.

14. The device according to claim 13 ,

Assignees

• Airbus Operations Sas

Inventors

• Prisse Lucien
• Lam Shang Leen Ludovic
• Pauvert Vincent
• Alejo Dominique

Classifications

• H02H9/041

  using a short-circuiting device · CPC title

• H02H9/043

  Protection of over-voltage protection device by short-circuiting · CPC title

• G01R31/52

  Testing for short-circuits, leakage current or ground faults · CPC title

• H02H3/025

  Disconnection after limiting, e.g. when limiting is not sufficient or for facilitating disconnection · CPC title

• H02H3/14

  responsive to occurrence of voltage on parts normally at earth potential {(monitoring earth connection H02H5/105)} · CPC title