Overcurrent protective device

Claim 2

An overcurrent protective device comprising first means adapted to be connected to an alternating current circuit for deriving therefrom unidirectional output voltage pulses having substantially the same configuration as the half wave portions of the alternating current in said circuit and a magnitude which is substantially directly proportional to that of the current in said circuit, level detecting means connected to said first means for producing a first output substantially instantaneously when the magnitude of said output pulses exceeds substantially a predetermined value, second means adapted to be connected to said alternating current circuit and to said level detecting means for producing a second output after a predetermined time delay which is actuated to start and to continue by said first output, said level detecting means including a timing circuit for maintaining said first output for a predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value.

Claim 3

The device as claimed in claim 1 wherein said predetermined time interval is slightly longer than one-half cycle of the alternating current in said alternating current circuit.

Claim 4

The device as claimed in claim 1 wherein said level detecting means includes a control means connected to said second means for normally preventing said second means from producing said second output until said level detecting means produces said first output to start said predetermined time delay and continues said first output until the end of said predetermined time delay.

Claim 5

An overcurrent protective device comprising first means adapted to be connected to an alternating current circuit for deriving tHerefrom unidirectional output voltage pulses having substantially the same configuration as the half-wave portions of the alternating current in said circuit and a magnitude which is substantially proportional to that of the current in said circuit, a capacitor for accumulating a charge, second means connected between said circuit and said capacitor for charging said capacitor, level detecting means connected between said first means and said capacitor to be responsive to the magnitude of said output pulses and including control means for normally preventing said second means from charging said capacitor until the magnitude of said output pulses exceeds substantially a predetermined value, third means connected to said capacitor for producing an output when the charge on said capacitor increases to a predetermined level after a predetermined time delay which is initiated by said level detecting means when the magnitude of said output pulses exceeds substantially said predetermined value, said level detecting means including a timing circuit connected to said control means for actuating said control means to permit said capacitor to continue charging for a predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value.

Claim 6

An overcurrent protective device comprising first means adapted to be connected to an alternating current circuit for deriving tHerefrom unidirectional output voltage pulses having substantially the same configuration as the half-wave portions of the alternating current in said circuit and a magnitude which is substantially proportional to that of the current in said circuit, a capacitor for accumulating a charge, second means connected between said circuit and said capacitor for charging said capacitor, level detecting means connected between said first means and said capacitor to be responsive to the magnitude of said output pulses and including control means for normally preventing said second means from charging said capacitor until the magnitude of said output pulses exceeds substantially a predetermined value, third means connected to said capacitor for producing an output when the charge on said capacitor increases to a predetermined level after a predetermined time delay which is initiated by said level detecting means when the magnitude of said output pulses exceeds substantially said predetermined value, said level detecting means including a timing circuit connected to said control means for actuating said control means to permit said capacitor to continue charging for a predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value.

Claim 7

The device as claimed in claim 4 wherein said time interval is slightly longer than one-half cycle of the alternating current in said alternating current circuit.

Claim 8

The device as claimed in claim 4 wherein an additional means is connected to said first means and to said third means for independently actuating said third means to produce an output substantially instantaneously when the magnitude of said output pulse exceeds substantially a predetermined value which is relatively larger than the predetermined value to which said level detecting means responds to initiate said predetermined time delay.

Claim 9

The device as claimed in claim 4 wherein said timing circuit comprises a resistor and a capacitor connected to a source of unidirectional voltage and to said control means to maintain said control means substantially nonconducting for said predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value.

Claim 10

A polyphase overcurrent protective device comprising first means adapted to be connected to all three phases of a three-phase alternating circuit for deriving therefrom unidirectional output voltage pulses having substantially the same configuration as the half-wave portions of the alternating current in said circuit and a magnitude which is substantially directly proportional only to the highest of the three-phase currents in said circuit, level detecting means responsive to the magnitude of said output pulses for producing a first output substantially instantaneously when the magnitude of said output pulses exceeds substantially a predetermined value, second means adapted to be connected to said circuit and to said level detecting means for producing a second output after a predetermined time delay which is actuated to start and to continue by said first output, said level detecting means including a timing circuit for maintaining said first output for a predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value.

Claim 11

A polyphase overcurrent protective device comprising first means adapted to be connected to all three phases of a three-phase alternating circuit for deriving therefrom unidirectional output voltage pulses having substantially the same configuration as the half-wave portions of the alternating current in said circuit and a magnitude which is substantially directly proportional only to the highest of the three-phase currents in said circuit, level detecting means responsive to the magnitude of said output pulses for producing a first output substantially instantaneously when the magnitude of said output pulses exceeds substantially a predetermined value, second means adapted to be connected to said circuit and to said level detecting means for producing a second output after a predetermined time delay which is actuated to start and to continue by said first output, said level detecting means including a timing circuit for maintaining said first output for a predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value.

Claim 12

The device as claimed in claim 8 wherein said predetermined time interval is slightly larger than one-half cycle of the alternating current in said alternating current circuit.

Claim 13

The device as claimed in claim 9 wherein an additional means is connected to said first means and to said second means for independently actuating said second means to produce said second output substantially instantaneously when the magnitude of said output pulses exceeds substantially a second predetermined value which is relatively larger than the predetermined value to which said level deTecting means responds to produce said first output.

Claim 14

A circuit breaker for use with an alternating current circuit comprising separable contacts adapted to be connected to said circuit, operating means for opening said contacts, and an overcurrent protective device operatively connected to said operating means and responsive to the current in said circuit for producing an output to actuate said operating means to open said contacts, said protective device comprising first means adapted to be connected to said circuit for deriving therefrom unidirectional output voltage pulses having substantially the same configuration as the half-wave portions of the alternating current in said circuit and a magnitude which is substantially directly portional to that of the current in said circuit, level detecting means connected to said first means for producing a first output substantially instantaneously when the magnitude of said output pulses exceeds substantially a predetermined value, second means adapted to be connected to said circuit and to said level detecting means for producing a second output after a predetermined time delay which is actuated to start and to continue by said first output, said level detecting circuit including a timing circuit for maintaining said first output for a predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value, and third means operatively connected between said second means and said operating means for producing an additional output in response to said second output to actuate said operating means to open said contacts.

Claim 15

A circuit breaker for use with an alternating current circuit comprising separable contacts adapted to be connected to said circuit, operating means for opening said contacts, and an overcurrent protective device operatively connected to said operating means and responsive to the current in said circuit for producing an output to actuate said operating means to open said contacts, said protective device comprising first means adapted to be connected to said circuit for deriving therefrom unidirectional output voltage pulses having substantially the same configuration as the half-wave portions of the alternating current in said circuit and a magnitude which is substantially directly portional to that of the current in said circuit, level detecting means connected to said first means for producing a first output substantially instantaneously when the magnitude of said output pulses exceeds substantially a predetermined value, second means adapted to be connected to said circuit and to said level detecting means for producing a second output after a predetermined time delay which is actuated to start and to continue by said first output, said level detecting circuit including a timing circuit for maintaining said first output for a predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value, and third means operatively connected between said second means and said operating means for producing an additional output in response to said second output to actuate said operating means to open said contacts.

Claim 16

The circuit breaker as claimed in claim 11 wherein said predetermined time interval is slightly longer than one-half cycle of the alternating current in said circuit.

Claim 17

The circuit breaker as claimed in claim 11 wherein said level detecting means includes a control means connected to said second means for normally preventing said second means from producing said second output until said level detecting means produces said first output to start said predetermined time delay and continues said first output until the end of said predetermined time delay.

Claim 18

A circuit breaker for use with an alternating current circuit comprising separable contacts adapted to be connected to said circuit, operating means for opening said contacts, and an overcurrent protective device operatively connected to said operating means and responsive to the current in said circuit for producing an output to actuate said operating mean to open said contacts, said protective device comprising first means adapted to be connected to said circuit for deriving therefrom unidirectional output voltage pulses having substantially the same configuration as the half-wave portions of the alternating current in said circuit and a magnitude which is substantially proportional to that of the current in said circuit, a capacitor for accumulating charge, second means connected between said circuit and said capacitor for charging said capacitor, level detecting means connected between said first means and said capacitor to be responsive to the magnitude of said output pulses and including control means for normally preventing said second means from charging said capacitor until the magnitude of said output pulses exceeds substantially a predetermined value, and third means operatively connected between said capacitor and aid operating means for producing an output when the charge on said capacitor increases to a predetermined level after a predetermined time delay which is initiated by said level detecting means when the magnitude of said output pulses exceeds substantially said predetermined value to thereby actuate said operating means to open said contacts, said level detecting means including a timing circuit connected to said control means for actuating said control means to permit said capacitor to continue charging for a predetermined time interval when thE magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value.

Claim 19

A circuit breaker for use with an alternating current circuit comprising separable contacts adapted to be connected to said circuit, operating means for opening said contacts, and an overcurrent protective device operatively connected to said operating means and responsive to the current in said circuit for producing an output to actuate said operating mean to open said contacts, said protective device comprising first means adapted to be connected to said circuit for deriving therefrom unidirectional output voltage pulses having substantially the same configuration as the half-wave portions of the alternating current in said circuit and a magnitude which is substantially proportional to that of the current in said circuit, a capacitor for accumulating charge, second means connected between said circuit and said capacitor for charging said capacitor, level detecting means connected between said first means and said capacitor to be responsive to the magnitude of said output pulses and including control means for normally preventing said second means from charging said capacitor until the magnitude of said output pulses exceeds substantially a predetermined value, and third means operatively connected between said capacitor and aid operating means for producing an output when the charge on said capacitor increases to a predetermined level after a predetermined time delay which is initiated by said level detecting means when the magnitude of said output pulses exceeds substantially said predetermined value to thereby actuate said operating means to open said contacts, said level detecting means including a timing circuit connected to said control means for actuating said control means to permit said capacitor to continue charging for a predetermined time interval when thE magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value.

Claim 20

The circuit breaker as claimed in claim 14 wherein said time interval is slightly longer than one-half cycle of the alternating current in said circuit.

Claim 21

The combination as claimed in claim 14 wherein an additional means is connected to said first means and to said third means for independently actuating said third means to produce an output substantially instantaneously when the magnitude of said output pulses exceeds substantially a predetermined value which is relatively larger than the predetermined value to which said level detecting means responds to initiate said predetermined time delay.

Claim 22

The circuit breaker as claimed in claim 14 wherein said timing circuit comprising a resistor and a capacitor connected to a source of unidirectional voltage and to said control means to maintain said control means substantially nonconducting for said predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value to thereby permit said capacitor to continue charging during said predetermined time interval.

Claim 23

A circuit breaker for use with a three-phase alternating current circuit comprising three sets of separable contacts adapted to be connected to said circuits, operating means for opening said sets of contacts, and an overcurrent protective device operatively connected to said operating means and responsive to the currents in said circuit for producing an output to actuate said operating means to open said sets of contacts, said protective device comprising first means adapted to be connected to said circuit for deriving therefrom unidirectional output voltage pulses having substantially the same configuration as the half-wave portions of the alternating current in said circuit and a magnitude which is substantially proportional to that of the highest of the three-phase currents in said circuit, level detecting means responsive to the magnitude of said output pulses for producing a first output substantially instantaneously when the magnitude of said output pulse exceeds substantially a predetermined value, second means adapted to be connected to said circuit and to said level detecting means for producing a second output after a predetermined time delay which is actuated to start and to continue by said first output, said level detecting means including a timing circuit for maintaining said first output for a predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value, and third means operatively connected between said second means and said operating means for producing an additional output in response to said second output to actuate said operating means to open said three sets of contacts.

Claim 24

A circuit breaker for use with a three-phase alternating current circuit comprising three sets of separable contacts adapted to be connected to said circuits, operating means for opening said sets of contacts, and an overcurrent protective device operatively connected to said operating means and responsive to the currents in said circuit for producing an output to actuate said operating means to open said sets of contacts, said protective device comprising first means adapted to be connected to said circuit for deriving therefrom unidirectional output voltage pulses having substantially the same configuration as the half-wave portions of the alternating current in said circuit and a magnitude which is substantially proportional to that of the highest of the three-phase currents in said circuit, level detecting means responsive to the magnitude of said output pulses for producing a first output substantially instantaneously when the magnitude of said output pulse exceeds substantially a predetermined value, second means adapted to be connected to said circuit and to said level detecting means for producing a second output after a predetermined time delay which is actuated to start and to continue by said first output, said level detecting means including a timing circuit for maintaining said first output for a predetermined time interval when the magnitude of said output pulses decreases below said predetermined value after exceeding said predetermined value, and third means operatively connected between said second means and said operating means for producing an additional output in response to said second output to actuate said operating means to open said three sets of contacts.

Claim 25

The circuit breaker as claimed in claim 18 wherein said predetermined time interval is slightly longer than one-half cycle of the alternating current in said alternating current circuit.

Claim 26

The circuit breaker as claimed in claim 18 wherein an additional means is connected to said first means and to said third means for independently actuating said third means to produce said additional output substantially instantaneously when the magnitude of said output pulses exceeds substantially a second predetermined value which is relatively larger than the predetermined value to which said level detecting means responds to produce said first output.