Solid state trip circuit with digital timer
First Claim
1. An electrical circuit for actuating the trip mechanism of a circuit interrupter comprising:
- current sensing means having a pair of output terminals, said current sensing means cooperating with at least one electrical power conductor for sensing the amount of current flowing in said electrical power conductor and producing a sensed current signal indicative thereof;
a circuit neutral terminal;
power supply means connected to one of said output terminals of said current sensing means for receiving said sensed current signal therefrom, and also connected to said circuit neutral terminal;
a resistor connected between said circuit neutral terminal and the other of said output terminals of said current sensing means for developing a voltage signal proportional to said sensed current signal and for returning substantially all of said sensed current signal to the other of said output terminals of said current sensing means; and
control means responsive to the magnitude of said voltage signal for actuating the trip mechanism of said circuit interrupter when said current flowing in said electrical power conductor exceeds a predetermined level.
2 Assignments
0 Petitions
Accused Products
Abstract
An electrical circuit is provided for actuating the trip mechanism of a circuit interrupter and includes a current sensor having a pair of output terminals and designed to cooperate with at least one electrical power conductor to sense the amount of current flowing in that conductor. The circuit further includes a circuit neutral terminal. A power supply is provided having input terminals with one of the input terminals being connected to one of the output terminals of the current sensor for receiving the sensed current signal therefrom, the other of the input terminals being connected to the circuit neutral terminal. The power supply produces output power at a first voltage level during a first mode of operation of the electrical circuit and produces output power at a second voltage level during a second mode of operation of the electrical circuit, with the second voltage level being substantially higher than the first voltage level. Circuitry is connected to the circuit neutral terminal and the other of the output terminals of the current sensor for developing a voltage signal proportional to the sensed current signal. Control circuitry is provided responsive to the magnitude of the voltage signal for actuating the trip mechanism of the circuit interrupter when the current flowing in the electrical power conductor exceeds a predetermined level. When said electrical circuit is in said first mode of operation, the control circuit is connected to the power supply for receiving output power at the first voltage level. When the electrical circuit is in the second mode of operation, the control circuit is connected to the power supply circuit for receiving output power at the second voltage level. The control circuit further includes at least one amplifier circuit for amplifying the voltage signal to a desired level. The amplifier circuit includes a gain changing circuit to adjust the level at which the trip mechanism will be actuated. The control circuit further includes a digital timing circuit having a first signal producing circuit responsive to the magnitude of the voltage of the signal received at the input terminal of the timing circuit for producing pulses having a first frequency. The timing circuit further includes a second signal producing circuit responsive to the magnitude of the voltage of the signal received at the input terminal of the timing circuit for producing pulses having a second frequency. A gate circuit is connected to the first and second signal producing circuits for producing output pulses only when receiving pulses from both the first and second signal producing circuits. A counting circuit is connected to the gate circuit for counting the number of the output pulses whenever the magnitude of the voltage at the input terminal exceeds a predetermined level.
33 Citations
57 Claims
-
1. An electrical circuit for actuating the trip mechanism of a circuit interrupter comprising:
-
current sensing means having a pair of output terminals, said current sensing means cooperating with at least one electrical power conductor for sensing the amount of current flowing in said electrical power conductor and producing a sensed current signal indicative thereof; a circuit neutral terminal; power supply means connected to one of said output terminals of said current sensing means for receiving said sensed current signal therefrom, and also connected to said circuit neutral terminal; a resistor connected between said circuit neutral terminal and the other of said output terminals of said current sensing means for developing a voltage signal proportional to said sensed current signal and for returning substantially all of said sensed current signal to the other of said output terminals of said current sensing means; and control means responsive to the magnitude of said voltage signal for actuating the trip mechanism of said circuit interrupter when said current flowing in said electrical power conductor exceeds a predetermined level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. An electrical circuit for actuating the trip mechanism of a circuit interrupter comprising:
-
current sensing means cooperating with at least one electrical power conductor for sensing the amount of current flowing in said electrical power conductor and producing a sensed current signal indicative thereof; a power supply circuit electrically connected to said current sensing means for receiving said sensed current signal and for deriving power therefrom;
said power supply producing output power at a first voltage level during a first mode of operation of said electrical circuit and producing output power at a second voltage level during a second mode of operation of said electrical circuit, said second voltage level being at least approximately four times higher than said first voltage level;means for developing a voltage signal proportional to said sensed current signal; and control means responsive to the magnitude of said voltage signal for actuating the trip mechanism of said circuit interrupter when said current flowing in said electrical power conductor exceeds a predetermined level, said control means being connected to said power supply circuit for receiving said output power at said first voltage level during said first mode of operation, and said control means being connected to said power supply circuit for receiving said output power at said second voltage level during said second mode of operation. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
-
-
28. An electrical circuit for actuating the trip mechanism of a circuit interrupter comprising:
-
current sensing means cooperating with at least one electrical power conductor for sensing the amount of current flowing in said electrical power conductor and producing a sensed current signal indicative thereof; power supply means for receiving said sensed current signal and for deriving power therefrom; means for developing a voltage signal proportional to said sensed current signal; control means connected to said power supply means for receiving power therefrom and responsive to the magnitude of said voltage signal for actuating the trip mechanism of said circuit interrupter when said current flowing in said electrical power conductor exceeds a predetermined level, said control means including a first amplifier circuit for amplifying said voltage signal to a desired level, said first amplifier circuit including input and output terminals and means for changing the gain of said first amplifier circuit to thereby adjust the level at which said trip mechanism will be actuated; said control means further including a second amplifier circuit connected to the output of said first amplifier circuit for amplifying the output of said first amplifier circuit to a desired level, said second amplifier circuit including input and output terminals and means for changing the gain of said second amplifier circuit to thereby adjust another level at which said trip mechanism will be actuated; a ground fault current sensing means cooperating with said current sensing means for sensing ground fault currents in one or more electrical power conductors and producing a ground fault current signal indicative thereof, and means for developing a ground fault voltage signal proportional to said sensed ground fault current signal, said control means further including a third amplifier circuit for amplifying said ground fault voltage signal to a desired level, said third amplifier circuit including input and output terminals and means for changing the gain of said third amplifier circuit to thereby adjust the level at which said trip mechanism will be actuated; said control means further including a timing circuit having input and output terminals and a priority circuit connected to said first, second and third amplifier circuits for determining which of of the output terminals of said first, second and third amplifier circuits will be connected to the input terminal of said timing circuit. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
-
-
48. A digital timing circuit comprising:
-
an input terminal; first signal producing means responsive to the magnitude of the voltage of a signal received at said input terminal for producing pulses having a first frequency; second signal producing means responsive to the magnitude of the voltage of the signal received at said input terminal for producing pulses having a second frequency; gate circuit means connected to said first and second signal producing means for producing output pulses only when receiving pulses from both said first and second signal producing means; and counting means connected to said gate circuit means and responsive to an external control signal for counting the number of said output pulses and for delivering a signal indicative of the passage of a predetermined amount of time, wherein the time required for said counting means to reach a predetermined count is inversely proportional to the magnitude of the voltage of said signal received at said input terminal taken to the nth power, where n is an integer equal to or greater than two. - View Dependent Claims (49, 50, 51, 52, 53, 54, 55, 56)
-
-
57. An apparatus for interrupting a current flowing in a circuit comprising:
-
a pair of electrical contacts in series with said electrical conductor; an electrical contact mechanism including a mechanical trip mechanism for opening and closing said electrical contacts; and an electrical circuit for actuating said contact mechanism and including; current sensing means having a pair of output terminals, said current sensing means cooperating with at least one electrical power conductor for sensing the amount of current flowing in said electrical power conductor and producing a sensed current signal indicative thereof; a circuit neutral terminal; power supply means connected to one of said output terminals of said current sensing means for receiving said sensed current signal therefrom, and also connected to said circuit neutral terminal; a resistor connected between said circuit neutral terminal and the other of said output terminals of said current sensing means for developing a voltage signal proportional to said sensed current signal and for returning substantially all of said sensed current signal to the other of said output terminals of said current sensing means; and control means responsive to the magnitude of said voltage signal for actuating the trip mechanism of said circuit interrupter when said current flowing in said electrical power conductor exceeds a predetermined level.
-
Specification