Overcurrent sensing and restraint control for sectionalizing switch

Claim 2

In a protective device coupled to an electrical system and including switch means, switch opening means, and actuating circuit means for counting a series of signals and actuating said opening means after a predetermined number of signals occur, the combination comprising: current sensing means coupled to said system and being responsive to an overcurrent in said system to produce one of said signals to the actuating circuit means; restraint means for preventing operation of the current sensing means when said overcurrent is below a predetermined level; and voltage sensing means responsive to the presence of voltage in said system for actuating said restraint means.

Claim 3

The combination according to claim 1 further comprising another restraint means responsive to said voltage sensing means for preventing operation of the actuating means when voltage is present in the system at said switch means.

Claim 4

The combination according to claim 2 wherein said current sensing means is responsive only to ground overcurrent in said system.

Claim 5

The combination according to claim 3 wherein said protective device comprises a sectionalizing switch.

Claim 6

In a sectionalizing switch coupled to an electrical system and including a main switch, switch opening means, signal means for producing an electrical signal and actuating means for counting a series of said signals and actuating said opening means after a predetermined number of signals occur, the combination comprising: current sensing means coupled to said system and generating an input signal proportional to the level of current in said system, said sensing means including switch means responsive to a predetermined level of said input signal proportional to a predetermined overcurrent in said system to actuate said signal means; restraint means for changing the level of said input signal to prevent actuation of the signal means by the switch means in response to said predetermined overcurrent in said system; and voltage sensing means coupled to said system and said restraint means, and responsive to the presence of voltage in said system for actuating said restraint means.

Claim 7

In a sectionalizing switch coupled to an electrical system and including a main switch, switch opening means, signal means for producing an electrical signal and actuating means for counting a series of said signals and actuating said opening means after a predetermined number of signals occur, the combination comprising: current sensing means coupled to said system and generating an input signal proportional to the level of current in said system, said sensing means including switch means responsive to a predetermined level of said input signal proportional to a predetermined overcurrent in said system to actuate said signal means; restraint means for changing the level of said input signal to prevent actuation of the signal means by the switch means in response to said predetermined overcurrent in said system; and voltage sensing means coupled to said system and said restraint means, and responsive to the presence of voltage in said system for actuating said restraint means.

Claim 8

In a sectionalizing switch coupled to an electrical system and including a main switch, switch opening means, signal means for producing an electrical signal and actuating means for counting a series of said signals and actuating said opening means after a predetermined number of signals occur, the combination comprising: current sensing means coupled to said system and generating an input signal proportional to the level of current in said system, said sensing means including switch means responsive to a predetermined level of said input signal to actuate said signal means, said switch means comprises a static switching circuit having a predetermined conductive bias signal level and said input signal comprises the bias signal of said static switch circuit; restraint means for changing the level of said input signal to prevent actuation of the signal means by the switch means, and voltage sensing means coupled to said system and said restraint means for actuating said restraint means.

Claim 9

In a sectionalizing switch coupled to an electrical system and including a main switch, switch opening means, signal means for producing an electrical signal and actuating means for counting a series of said signals and actuating said opening means after a predetermined number of signals occur, the combination comprising: current sensing means coupled to said system and generating an input signal proportional to the level of current in said system, said sensing means including switch means responsive to a predetermined level of said input signal to actuate said signal means, said switch means comprises a static switching circuit having a predetermined conductive bias signal level and said input signal comprises the bias signal of said static switch circuit; restraint means for changing the level of said input signal to prevent actuation of the signal means by the switch means, and voltage sensing means coupled to said system and said restraint means for actuating said restraint means.

Claim 10

The combination according to claim 6 wherein said static switching circuit includes: a static switch having an input electrode and a biasing electrode receiving said bias signal, said electrodes being a conductive series circuit when said static switch is conductive, said series circuit having a voltage drop in a predetermined direction in response to an increase in temperature; and a static device connected in series with the series circuit of the static switch and having a voltage drop approximately equal to but in a direction opposite from said predetermined direction in response to an increase in temperature whereby said predetermined conductive bias signal level remains substantially constant.

Claim 11

The combination according to claim 5 wherein said restraint means includes timing means and is operative for a period of time determined by said timing means and beginning substantially simultaneously with the presence of voltage in said system at the sectionalizing switch.

Claim 12

In a sectionalizing switch coupled to an electrical system and including a main switch, switch opening means, signal means for producing an electrical signal and actuating means for counting a series of said signals and actuating said opening means after a predetermined number of signals occur, the combination comprising: current sensing means coupled to said system and generating an input signal proportional to the level of current in said system, said sensing means including switch means responsive to a predetermined level of said input signal to actuate said signal means; restraint means for changing the level of said input signal to prevent actuation of the signal means by the switch means, said restraint means includes timing means and is operative for a period of time determined by said timing means and beginning substantially simultaneously with the presence of voltage in said system at the sectionalizing switch; and voltage sensing means coupled to said system and said restraint means for actuating said restraint means, including said timing means in response to the initial presence of voltage in said system at said sectionalizing switch.

Claim 13

In a sectionalizing switch coupled to an electrical system and including a main switch, switch opening means, signal means for producing an electrical signal and actuating means for counting a series of said signals and actuating said opening means after a predetermined number of signals occur, the combination comprising: current sensing means coupled to said system and generating an input signal proportional to the level of current in said system, said sensing means including switch means responsive to a predetermined level of said input signal to actuate said signal means; restraint means for changing the level of said input signal to prevent actuation of the signal means by the switch means, said restraint means includes timing means and is operative for a period of time determined by said timing means and beginning substantially simultaneously with the presence of voltage in said system at the sectionalizing switch; and voltage sensing means coupled to said system and said restraint means for actuating said restraint means, including said timing means in response to the initial presence of voltage in said system at said sectionalizing switch.

Claim 14

The combination according to claim 9 wherein: said current sensing means is responsive only to ground current in said system; said sectionalizing switch includes a voltage transformer coupled to said system and supplying energy to said current sensing means and restraint means; and said actuating means includes energy storage means for providing switch opening power to the switch opening means, said energy sTorage means being coupled to said voltage transformer and receiving energy from said transformer.

Claim 15

The combination according to claim 10 further comprising another restraint means connected to said voltage transformer for preventing operation of the actuating means when voltage is present in the system at said switch means.

Claim 16

In a sectionalizing switch coupled to an electrical system producing alternating voltage and current quantities and including switch means, switch opening means, and actuating circuit means for counting a series of signals and actuating said opening means after a predetermined number of signals occur, the combination comprising: current sensing means coupled to said system and being responsive to an overcurrent in said system to produce one of said signals to the actuating circuit means; restraint circuit means including timing means for providing a timing period and being coupled to the current sensing means for preventing operation of the current sensing means when said overcurrent is below a predetermined value, said restraint circuit means being initially operative in response to the presence of one of said voltage and current quantities and continuing operative during said timing period; and sensing means responsive to the presence of one of said alternating current and voltage quantities for actuating said restraint means.

Claim 17

In a sectionalizing switch coupled to an electrical system producing alternating voltage and current quantities and including switch means, switch opening means, and actuating circuit means for counting a series of signals and actuating said opening means after a predetermined number of signals occur, the combination comprising: current sensing means coupled to said system and being responsive to an overcurrent in said system to produce one of said signals to the actuating circuit means; restraint circuit means including timing means for providing a timing period and being coupled to the current sensing means for preventing operation of the current sensing means when said overcurrent is below a predetermined value, said restraint circuit means being initially operative in response to the presence of one of said voltage and current quantities and continuing operative during said timing period; and sensing means responsive to the presence of one of said alternating current and voltage quantities for actuating said restraint means.

Claim 18

The combination according to claim 12 wherein said restraint circuit means has a normal condition and also has a switched condition when operative.

Claim 19

The combination according to claim 12 wherein said restraint circuit means includes static switch means having a first condition and a second condition for maintaining the restraint circuit means operative while in said second condition, said static switch means being in said second condition only during said timing period.

Claim 20

The combination according to claim 14 wherein said first condition is the conductive condition of the static switch means during normal operating conditions of the electrical system and said second condition is a conductive condition opposite that of the first condition.