MV switching device of the electromagnetic type having an improved power drive circuit

A MV switching device, comprising:

• an electromagnetic actuator for actuating electric contacts of said switching device, said electromagnetic actuator having a first excitation winding, a second excitation winding and a third excitation winding of said electromagnetic actuator;
• power supply means for supplying electric power to said electromagnetic actuator;
• a power drive circuit for driving said electromagnetic actuator, said power drive circuit comprising:
• a first input terminal and a second input terminal electrically connected to said power supply means and establishing a voltage Vc between the first and second input terminals;
• a first output terminal, a second output terminal and a third output terminal electrically connected respectively to said first excitation winding, said second excitation winding and said third excitation winding of said electromagnetic actuator;
• a first circuit branch, which is electrically connected between said first and second input terminals and comprises said first output terminal, said first circuit branch comprising a first circuit branch portion between said first input terminal and said first output terminal, which comprises a first power switch configured to allow/block the flow of a current along said first circuit branch portion, and a second circuit branch portion between said first output terminal and said second input terminal, which comprises a second power switch configured to allow/block the flow of a current along said second circuit branch portion;
• a first auxiliary circuit in parallel with the first circuit branch and connected to the first output terminal, and including a voltage divider to present a voltage at the first output terminal that is 10-90% of Vc when the first and second power switches are blocking the flow of current;
• a second circuit branch, which is electrically connected between said first and second input terminals and comprises said second output terminal, said second circuit branch comprising a third circuit branch portion between said second output terminal and said second input terminal, which comprises a third power switch configured to allow/block the flow of a current along said third circuit branch portion, and a fourth circuit branch portion between said first input terminal and said second output terminal, which comprises a fourth power switch configured to allow/block the flow of a current along said fourth circuit branch portion;
• a second auxiliary circuit in parallel with the second circuit branch and connected to the second output terminal, and including a voltage divider to present a voltage at the second output terminal that is 10-90% of Vc when the third and fourth power switches are blocking the flow of current;
• a third circuit branch, which is electrically connected between said first and second input terminals and comprises said third output terminal, said third circuit branch comprising a fifth circuit branch portion between said third output terminal and said second input terminal, which comprises a fifth power switch configured to allow/block the flow of a current along said fifth circuit branch portion, and a sixth circuit branch portion between said first input terminal and said third output terminal, which comprises a sixth power switch configured to allow/block the flow of a current along said fourth circuit branch portion;
• a third auxiliary circuit in parallel with the third circuit branch and connected to the third output terminal, and including a voltage divider to present a voltage at the third output terminal that is 10-90% of Vc when the fifth and sixth power switches are blocking the flow of current;
• wherein said power drive circuit comprises:
• first sensing means configured to provide first sensing signals indicative of a current flowing along said first circuit branch;
• second sensing means configured to provide second sensing signals indicative of a current flowing along said second circuit branch;
• seventh sensing means configured to provide seventh sensing signals indicative of a current flowing along said third circuit branch.

A power drive circuit for a MV switching device, said switching device comprising an electromagnetic actuator for actuating electric contacts of said switching device and power supply means for supplying electric power to said electromagnetic actuator, said power drive circuit comprising:

• a first input terminal and a second input terminal electrically connectable to said power supply means and establishing a voltage Vc between the first and second input terminals;
• at least a first output terminal and a second output terminal electrically connectable to at least an excitation winding of said electromagnetic actuator;
• a first circuit branch, which is electrically connected between said first and second input terminals and comprises said first output terminal, said first circuit branch comprising a first circuit branch portion between said first input terminal and said first output terminal, which comprises a first power switch configured to allow/block the flow of a current along said first circuit branch portion, and a second circuit branch portion between said first output terminal and said second input terminal, which comprises a second power switch configured to allow/block the flow of a current along said second circuit branch portion;
• a first auxiliary circuit in parallel with the first circuit branch and connected to the first output terminal, and including a voltage divider to present a voltage at the first output terminal that is 10-90% of Vc when the first and second power switches are blocking the flow of current;
• a second circuit branch, which is electrically connected between said first and second input terminals and comprises said second output terminal, said second circuit branch comprising a third circuit branch portion between said second output terminal and said second input terminal, which comprises a third power switch configured to allow/block the flow of a current along said third circuit branch portion, and a fourth circuit branch portion between said first input terminal and said second output terminal, which comprises a fourth power switch configured to allow/block the flow of a current along said fourth circuit branch portion;
• a second auxiliary circuit in parallel with the second circuit branch and connected to the second output terminal, and including a voltage divider to present a voltage at the second output terminal that is 10-90% of Vc when the third and fourth power switches are blocking the flow of current;
• wherein it comprises:
• first sensing means configured to provide first sensing signals indicative of the current flowing along said first circuit branch;
• and
• second sensing means configured to provide second sensing signals indicative of the current flowing along said second circuit branch.

A power drive circuit for a MV switching device, said switching device comprising an electromagnetic actuator for actuating electric contacts of said switching device and power supply means for supplying electric power to said electromagnetic actuator, said power drive circuit comprising:

• a first input terminal and a second input terminal electrically connectable to said power supply means and establishing a voltage Vc between the first and second input terminals;
• a first output terminal, a second output terminal and a third output terminal electrically connectable respectively to a first excitation winding, a second excitation winding and a third excitation winding of said electromagnetic actuator;
• a first circuit branch, which is electrically connected between said first and second input terminals and comprises said first output terminal, said first circuit branch comprising a first circuit branch portion between said first input terminal and said first output terminal, which comprises a first power switch configured to allow/block the flow of a current along said first circuit branch portion, and a second circuit branch portion between said first output terminal and said second input terminal, which comprises a second power switch configured to allow/block the flow of a current along said second circuit branch portion;
• a first auxiliary circuit in parallel with the first circuit branch and connected to the first output terminal, and including a voltage divider to present a voltage at the first output terminal that is 10-90% of Vc when the first and second power switches are blocking the flow of current;
• a second circuit branch, which is electrically connected between said first and second input terminals and comprises said second output terminal, said second circuit branch comprising a third circuit branch portion between said second output terminal and said second input terminal, which comprises a third power switch configured to allow/block the flow of a current along said third circuit branch portion, and a fourth circuit branch portion between said first input terminal and said second output terminal, which comprises a fourth power switch configured to allow/block the flow of a current along said fourth circuit branch portion;
• a second auxiliary circuit in parallel with the second circuit branch and connected to the second output terminal, and including a voltage divider to present a voltage at the second output terminal that is 10-90% of Vc when the third and fourth power switches are blocking the flow of current;
• a third circuit branch, which is electrically connected between said first and second input terminals and comprises said third output terminal, said third circuit branch comprising a fifth circuit branch portion between said third output terminal and said second input terminal, which comprises a fifth power switch configured to allow/block the flow of a current along said fifth circuit branch portion, and a sixth circuit branch portion between said first input terminal and said third output terminal, which comprises a sixth power switch configured to allow/block the flow of a current along said fourth circuit branch portion;
• a third auxiliary circuit in parallel with the third circuit branch and connected to the third output terminal, and including a voltage divider to present a voltage at the third output terminal that is 10-90% of Vc when the fifth and sixth power switches are blocking the flow of current;
• wherein it comprises:
• first sensing means configured to provide first sensing signals indicative of a current flowing along said first circuit branch;
• second sensing means configured to provide second sensing signals indicative of a current flowing along said second circuit branch;
• seventh sensing means configured to provide seventh sensing signals (D7) indicative of the current flowing along said third circuit branch.