Two terminal active arc suppressor
AssigneeSchweitzer Engineering Laboratories, Inc.
InventorTony J. Lee
Life of this patent
Estimating the term…
Abstract
The arc suppression circuit includes an insulated gate bipolar junction transistor (IGBT) connected across the electrical switch contacts to be protected. When the contacts open, the combination of added Miller capacitance and the gate-to-emitter capacitance of the IGBT results in the IGBT turning on. The IGBT is quickly turned off thereafter by a second transistor, which turns on as the voltage across the suppression circuit rises following turn-on of the IGBT. The turning on of the second transistor results in the first power transistor quickly and abruptly turning off so that relatively little of the load energy is dissipated in the power transistor.
Claims24
A circuit for suppression of arcing across electrical contacts, comprising:
- a power transistor connected across the contacts;
- capacitance means connected between the contacts and the power transistor but not directly across the contacts, sufficient that the power transistor quickly turns on when the contacts begin to open, providing a current path around the contacts, thereby preventing arcing across the contacts;
- means for turning off the power transistor following sufficient separation of the contacts to prevent arcing, wherein turning off of the power transistor is sufficiently rapid that a substantial amount of load energy remains to be dissipated;
- and
- voltage limiting means to limit any flyback voltage resulting from the power transistor turning off to a selected level and to dissipate remaining load energy.
A circuit for suppression of arcing across electrical contacts, comprising:
- a power transistor connected across the contacts;
- capacitance means connected between the contacts and the power transistor but not directly across the contacts, sufficient that the power transistor quickly turns on when the contacts begin to open, providing a current path around the contacts, thereby preventing arcing across the contacts the contacts;
- means for turning off the power transistor following sufficient separation of the contacts to prevent arcing, wherein the circuit is used with a voltage limiting means to limit any flyback voltage resulting from the power transistor turning off to a selected level;
- and
- a second transistor connected to the power transistor in such a manner that, as voltage across the suppression circuit rises following opening of the contacts, the second transistor turns on, resulting in the power transistor turning off so quickly that only a relatively small portion of load energy following opening of the contacts is dissipated by the power transistor.
Dependencies are inferred from the claim text.