Ground fault circuit interrupter system with uncommitted contacts

• US 5,825,599 A
• Filed: 05/05/1997
• Issued: 10/20/1998
• Est. Priority Date: 05/05/1997
• Status: Expired due to Term

• Current Assignee: Leviton Manufacturing Company Incorporated
• Original Assignee: Leviton Manufacturing Company Incorporated
• Inventors: Rosenbaum, Saul
• Primary Examiner(s): Leja, Ronald W.
• Application Number:
  US08/851,518
• Time in Patent Office: 533 Days
• Field of Search: 324/424, 340/635, 340/638, 340/644, 340/650, 340/651, 340/652, 340/654, 361/42-50
• US Class Current: 361/45
• CPC Class Codes: H02H 1/0084 by means of pilot wires or a telephone network; watching of these wires
• CPC Class Codes: H02H 3/04 with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned watching of pilot wires H02H1/0084; protection of protective arrangements H02H7/008; indication of the state of electronic switches H03K17/18
• CPC Class Codes: H02H 3/334 with means to produce an artificial unbalance for other protection or monitoring reasons or remote control H02H3/338 takes precedence

Abstract

A ground fault circuit interrupt system with uncommitted contacts is provided which includes line-side system, phase, neutral and ground terminals electrically connectable to phase, neutral and ground terminals of an AC power source and load-side system, phase, neutral and ground terminals electrically connectable, respectively, to phase, neutral and ground terminals of an electrical load. The system includes a ground fault circuit interrupter including line- and load-side phase and neutral terminals for electrical connection to the line-side system, phase and neutral terminals for controlling a state of conduction of AC current between the source and electrical load in accordance with a detection of an interrupt condition. A relay switch is also included which has a relay coil and phase and neutral contacts such that line and load ends of the phase contact are electrically connected, respectively, to a GFCI load-side phase terminals and load-side system, phase terminal, line and load ends of the neutral contact are electrically connected, respectively, to a GFCI load-side neutral terminal and load-side system, neutral terminal; and the relay coil is electrically coupled between the load ends of the phase and neutral contacts for controlling said contacts in response to the interrupt condition.

Claims

1. A ground fault circuit interrupter device with remote sensing ability comprising:

a) a ground fault circuit interrupter (GFCI) means including line and load side phase and neutral terminals and a relay switch for controlling current flow between an AC source and a electrical circuit to be protected in accordance with the detection of an interrupt condition;

b) said GFCI means comprising first means for detecting a first current flowing from said AC source to said electrical circuit, second means for detecting a second current flowing from said electrical circuit to said AC source and an integrated circuit device to provide an output signal proportional to any difference between said first current and said second current and including comparing means to receive said output signal;

c) a reference signal generator for generating a reference signal indicative of the maximum allowable difference between said first and second currents, said reference signal generator coupled to said integrated circuit device to provide said reference signal thereto;

d) said comparing means of said integrated circuit device comparing said output signal with said reference signal and providing an interrupt signal if said output signal exceeds said reference signal;

e) said relay switch includes a relay coil, a selectively movable phase contact having a line and a load end and a selectively movable neutral contact having a line and a load end;

f) said line and load ends of said selectively movable phase contact are electrically connected to said load side phase terminal of said GFCI means and to a phase terminal of said electrical circuit, respectively;

g) said line and load ends of said selectively movable neutral contact are electrically connected between a load side neutral terminal of said GFCI means and a neutral terminal of said electrical circuit, respectively;

h) said relay coil is electrically coupled between said line ends of said selectively movable phase and selectively movable neutral contacts for moving said contacts in response to the receipt of said interrupt condition; and

i) two electrical contacts electrically connected to said GFCI means such that a signal present at said electrical contacts may be continuously monitored to determine a state of current flow through said GFCI means phase and neutral contacts.

2. The ground fault circuit interrupter device defined by claim 1, wherein one of said two electrical contacts comprises a first line side phase terminal and a first load side phase terminal, wherein said first line side phase terminal is electrically connected to said GFCI means line side phase terminal and said first load side phase terminal is electrically connected to a monitoring device, and the other of said two electrical contacts comprises a second line side neutral terminal and a second load side neutral terminal, wherein said second line side neutral terminal is electrically connected to said GFCI means line side neutral terminal and said second load side neutral terminal is electrically connected to said monitoring device.

3. A method for protecting an electrical device from ground faults utilizing a ground fault circuit interrupter (GFCI) wherein an operable state of said GFCI is continuously monitored for maintaining the operable integrity of said electrical device and wherein said GFCI is electrically connected between an AC power source and said electrical device comprising the steps of:

a) detecting a first amount of AC current flowing from said AC power source to said electrical device utilizing said GFCI;

b) detecting a second amount of AC current flowing from said electrical device to said AC power source utilizing said GFCI;

c) generating a difference signal indicative of a difference between said first and second amounts of AC current flowing;

d) comparing said difference signal to a reference signal which is proportional to the maximum allowable difference in current flow and defining an interrupt condition when said difference signal exceeds said reference signal;

e) maintaining a pair of uncommitted contacts at a portion of said GFCI to permit the monitoring of a state of current flow therethrough; and

f) interrupting said flow of AC current between said AC power source and said electrical device upon the occurrence of said interrupt condition such that an operable state signal indicating the same is present at said uncommitted contacts.