Monitoring and shutdown apparatus

Claim 2

Control apparatus adapted to be used in monitoring systems in which a monitor establishes a first signal whenever a measured variable exceeds a preselected limit, said apparatus comprising: a first one-shot multivibrator adapted to change from a first state to a second state when an input signal is applied thereto and to change back to the second state at the end of a first predetermined time interval after the input signal is received, the input of said first multivibrator being adapted to receive said first signal; a second one-shot multivibrator adapted to change from a first state to a second state when an input signal is applied thereto and to change back to the first state at the end of a second predetermined time interval after the input signal is received, said second predetermined time interval being longer than said first predetermined time interval; means to connect said first multivibrator to said second multivibrator so that an input signal is applied to said second multivibrator from said first multivibrator when said first multivibrator changes from the second state to the first state; an AND circuit adapted to provide an output signal when actuated by two input signals; means connecting said AND circuit to said first and second multivibrators so that first and second input signals are applied to said AND circuit from said first and second multivibrators, respectively, when said first and second multivibrators are in their respective second states, thereby actuating said AND circuit; and a shutdown device connected to said AND circuit to be actuated by said output signal.

Claim 3

Control apparatus adapted to be used in monitoring sytems in which a monitor establishes a first signal whenever a measured variable exceeds a preselected limit, said apparatus comprising: a first one-shot multivibrator adapted to change from a first state to a second state when an input signal is applied thereto and to change back to the second state at the end of a first predetermined time interval after the input signal is received, the input of said first multivibrator being adapted to receive said first signal; a second one-shot multivibrator adapted to change from a first state to a second state when an input signal is applied thereto and to change back to the first state at the end of a second predetermined time interval after the input signal is received, said second predetermined time interval being longer than said first predetermined time interval; means to connect said first multivibrator to said second multivibrator so that an input signal is applied to said second multivibratOr from said first multivibrator when said first multivibrator changes from the second state to the first state; and an AND circuit adapted to provide an output signal when actuated by two input signals, said AND circuit comprises a capacitor having one terminal connected to a point of reference potential, a resistor connected in parallel with said capacitor, a first diode connected between the second terminal of said capacitor and said first multivibrator so that a first potential is applied to said first diode when said multivibrator is in said first state and a second potential is applied to said first diode when said first multivibrator is in said second state, and a second diode connected between the second terminal of said capacitor and said second multivibrator so that a first potential is applied to said second diode when said second multivibrator is in said first state and a second potential is applied to said second diode when said second multivibrator is in said second state, said capacitor discharging through said resistor when said first and second multivibrators are in respective second states, and further comprising a unijunction transistor having the emitter thereof connected to the second terminal of said capacitor, means applying a potential difference between the two bases of said unijunction transistor, and means connected to one of said bases to establish an output signal when said unijunction transistor is in a conductive state.

Claim 4

Control apparatus adapted to be used in monitoring sytems in which a monitor establishes a first signal whenever a measured variable exceeds a preselected limit, said apparatus comprising: a first one-shot multivibrator adapted to change from a first state to a second state when an input signal is applied thereto and to change back to the second state at the end of a first predetermined time interval after the input signal is received, the input of said first multivibrator being adapted to receive said first signal; a second one-shot multivibrator adapted to change from a first state to a second state when an input signal is applied thereto and to change back to the first state at the end of a second predetermined time interval after the input signal is received, said second predetermined time interval being longer than said first predetermined time interval; means to connect said first multivibrator to said second multivibrator so that an input signal is applied to said second multivibratOr from said first multivibrator when said first multivibrator changes from the second state to the first state; and an AND circuit adapted to provide an output signal when actuated by two input signals, said AND circuit comprises a capacitor having one terminal connected to a point of reference potential, a resistor connected in parallel with said capacitor, a first diode connected between the second terminal of said capacitor and said first multivibrator so that a first potential is applied to said first diode when said multivibrator is in said first state and a second potential is applied to said first diode when said first multivibrator is in said second state, and a second diode connected between the second terminal of said capacitor and said second multivibrator so that a first potential is applied to said second diode when said second multivibrator is in said first state and a second potential is applied to said second diode when said second multivibrator is in said second state, said capacitor discharging through said resistor when said first and second multivibrators are in respective second states, and further comprising a unijunction transistor having the emitter thereof connected to the second terminal of said capacitor, means applying a potential difference between the two bases of said unijunction transistor, and means connected to one of said bases to establish an output signal when said unijunction transistor is in a conductive state.

Claim 5

The apparatus of claim 2 wherein said means to establish an output signal comprises a silicon controlled rectifier, means to apply a potential across said rectifier, and means to connect said rectifier to said one base to trigger said rectifier in response to conduction by said transistor.

Claim 6

The apparatus of claim 2 wherein each of said multivibrators comprises first and second transistors each having an emitter, a collector and a base, the base of the first transistor being the input of the multivibrator and the collector of the second transistor being the output of the multivibrator, means connecting the emitter and the collector of each transistor in circuit with a source of potential, and a capacitor connected between the base of the first transistor and the collector of the second transistor, said means connecting said first multivibrator to said second multivibrator comprises means connecting the collector of the first transistor of the first multivibrator to the base of the first transistor of the second multivibrator, said first diode is connected to the collector of the second transistor of the first multivibrator, and said second diode is connected to the collector of the second transistor of the second multivibrator.

Claim 7

Control apparatus adapted to be used in monitoring systems in which a monitor establishes a first signal whenever a measured variable exceeds a preselected limit, said apparatus comprising: a first one-shot multivibrator adapted to change from a first state to a second state when an input signal is applied thereto and to change back to the second state at the end of a first predetermined time interval after the input signal is received, the input of said first multivibrator being adapted to receive said first signal; a second one-shot multivibrator adapted to change from a first state to a second state when an input signal is applied thereto and to change back to the first state at the end of a second predetermined time interval after the input signal is received, said second predetermined time interval being longer than said first predetermined time interval; means to connect said first multivibrator to said second multivibrator so that an input signal is applied to said second multivibrator from said first multivibrator when said first multivibrator changes from the second state to the first state; an AND circuit adapted to provide an output signal when actuated by two input signals; and an alarm connected to said AND circuit to be actuated by said output siGnal.

Claim 8

Control apparatus adapted to be used in monitoring systems in which a monitor establishes a first signal whenever a measured variable exceeds a preselected limit, said apparatus comprising: a first one-shot multivibrator adapted to change from a first state to a second state when an input signal is applied thereto and to change back to the second state at the end of a first predetermined time interval after the input signal is received, the input of said first multivibrator being adapted to receive said first signal; a second one-shot multivibrator adapted to change from a first state to a second state when an input signal is applied thereto and to change back to the first state at the end of a second predetermined time interval after the input signal is received, said second predetermined time interval being longer than said first predetermined time interval; means to connect said first multivibrator to said second multivibrator so that an input signal is applied to said second multivibrator from said first multivibrator when said first multivibrator changes from the second state to the first state; an AND circuit adapted to provide an output signal when actuated by two input signals; and an alarm connected to said AND circuit to be actuated by said output siGnal.