Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
149 words
Gas-blast electric switchgear including an interrupter unit comprising a chamber having a continuous filling of pressurized gas, disposed within said chamber a pair of relatively movable hollow contacts which cooperate together to provide a continuous passage when engaged and which when disengaged provide respective exhaust passages for gas blasting through the gap between the contacts, an exhaust valve connected between a low-pressure region and the interior of one of the contacts and operable to cause a rapid reduction of gas pressure in the continuous passage prior to disengagement of the contacts, and a further exhaust valve connected between the low-pressure region and the interior of the other contact and having operating means automatically effective to open the further exhaust valve in response to such a rapid reduction of gas pressure in the continuous passage and to reclose the further exhaust valve upon the expiration of a predetermined time interval.
Claim 2
Dependent Claim
149 words
Gas-blast electric switchgear including an interrupter unit comprising a chamber having a continuous filling of pressurized gas, disposed within said chamber a pair of relatively movable hollow contacts which cooperate together to provide a continuous passage when engaged and which when disengaged provide respective exhaust passages for gas blasting through the gap between the contacts, an exhaust valve connected between a low-pressure region and the interior of one of the contacts and operable to cause a rapid reduction of gas pressure in the continuous passage prior to disengagement of the contacts, and a further exhaust valve connected between the low-pressure region and the interior of the other contact and having operating means automatically effective to open the further exhaust valve in response to such a rapid reduction of gas pressure in the continuous passage and to reclose the further exhaust valve upon the expiration of a predetermined time interval.
Claim 3
Dependent Claim
110 words
Gas-blast electric switchgear as claimed in claim 1, wherein the further exhaust valve includes a sleeve valve member having an integral piston part, the cylinder space on one side of said piston part being in communication with pressurized gas and the cylinder space on the other side of said piston part being in communication with the continuous passage prior to the opening of the further exhaust valve so that, upon a rapid reduction of gas pressure in the continuous passage, the sleeve valve member moves to uncover an exhaust port so as to place the continuous passage in communication with the exhaust port, and thus open the further exhaust vAlve.
Claim 4
Dependent Claim
114 words
Gas-blast electric switchgear as claimed in claim 2, wherein the further exhaust valve includes a chamber, the interior of which is in communication with the interior of said other contact through a metering bore formed in a shuttle valve member, the arrangement being such that, due to controlled drainage through the metering bore during said predetermined time interval, the pressure within the chamber falls to such an extent that, at the end of said predetermined time interval, the shuttle valve member moves to place one side of a piston in communication with pressurized gas which causes movement of the piston and results in movement of the sleeve valve member to close the exhaust port.
Claim 5
Dependent Claim
40 words
Gas-blast electric switchgear as claimed in claim 3, wherein, in order to uncover the exhaust port, the sleeve valve member moves away from said other contact and into engagement with a secondary valve member which is integral with said piston.
Claim 6
Dependent Claim
62 words
Gas-blast electric switchgear as claimed in claim 4, wherein the secondary valve member includes a tube which slidably contains the shuttle valve member so that the metering bore is in communication with the interior of the tube which is in communication with the exhaust port when the sleeve valve member is in its open position in engagement with the secondary valve member.
Claim 7
Dependent Claim
93 words
Gas-blast electric switchgear as claimed in claim 3, wherein in order to uncover the exhaust port, the sleeve valve member moves towards said other contact against the action of spring means urging it into its closed position, and wherein movement of the shuttle member at the end of said predetermined time interval closes the communication between said other side of said piston part and the continuous passage and places said other side in communication with pressurized gas so that the sleeve valve member is moved into its closed position by the spring means.