Ground fault circuit interrupt system including auxiliary surge suppression ability

• US 5,654,857 A
• Filed: 07/19/1995
• Issued: 08/05/1997
• Est. Priority Date: 07/19/1995
• Status: Expired due to Fees

• Current Assignee: Leviton Manufacturing Company Incorporated
• Original Assignee: Leviton Manufacturing Company Incorporated
• Inventors: Gershen, Bernard
• Primary Examiner(s): Gaffin, Jeffrey A.
• Assistant Examiner(s): JACKSON, STEPHEN W
• Application Number:
  US08/504,211
• Time in Patent Office: 748 Days
• Field of Search: 361/42, 361/43, 361/45, 361/118, 361/56, 361/93
• US Class Current: 361/42
• CPC Class Codes: H02H 3/33 using summation current transformers H02H3/347 takes precedence
• CPC Class Codes: H02H 9/042 comprising means to limit the absorbed power or indicate damaged over-voltage protection device

Abstract

A ground fault circuit interrupt system with auxiliary surge suppression ability is provided which includes line-side system, phase, neutral and ground terminals electrically connectable to phase, neutral and ground terminals of an AC 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 ports for electrical connection to the line-side system, phase and neutral terminals for controlling a state of conduction of AC 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 port and load-side system, phase terminal, line and load ends of the neutral contact are electrically connected, respectively, to a GFCI load-side neutral port 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. First second and third transient voltage surge suppressors electrically connected between the line-side system, phase and neutral terminals, phase and ground terminals and neutral and ground terminals for transient voltage surge suppression protection.

Claims

1. A ground fault circuit interrupt system with auxiliary surge suppression capability, comprising:

line-side system phase, neutral and ground terminals electrically connectable to phase, neutral and ground terminals of an AC source, respectively;

load-side system phase, neutral and ground terminals electrically connectable, respectively, to phase, neutral and ground terminals of an electrical load;

a ground fault circuit interrupter including line- and load-side phase; and

neutral ports, wherein said line-side phase and neutral ports are electrically connected to said line-side system phase and neutral terminals and said load-side phase and neutral ports are electrically connected to said load-side system phase and neutral terminals for controlling a state of conduction of AC between said source and said electrical load in accordance with a detection of an interrupt condition; and

first, second, and third transient voltage surge suppressors electrically connected between said line-side system and all of the following;

phase and neutral terminals, phase and ground terminals, and neutral and ground terminals, for transient voltage surge suppression protection.

2. The ground fault circuit interrupt system defined by claim 1, wherein said GFCI includes:

a relay switch including a relay coil and phase and neutral contacts, wherein line and load ends of said phase contact are electrically connected to a GFCI load-side phase port and load-side system phase terminal, respectively, wherein line and load ends of said neutral contact are electrically connected to a GFCI load-side neutral port and load-side system neutral terminal, respectively, and wherein said relay coil is electrically coupled between said load ends of said phase and neutral contacts for controlling said contacts in response to said interrupt condition.

3. The ground fault circuit interrupt system defined by claim 1, wherein said GFCI monitors a phase current flowing from a source to a load and a neutral current flowing from said load to said source, and generates an interrupt signal based on a detected difference of said monitored line and neutral currents.

4. The ground fault circuit interrupt system defined by claim 1, wherein said first, second and third TVSS devices prevent voltages present at said nodes from exceeding 400 volts.

5. The ground fault circuit interrupt system defined by claim 1, wherein said TVSS devices include metal oxide varistors.

6. The ground fault circuit interrupt system defined by claim 1, further including:

second and third line-side system phase terminals and second and third load-side system load terminals, wherein said system phase terminals are electrically connectable to corresponding phases of a three-phase AC source and said system load terminals are electrically connectable to corresponding phases of load; and

fourth, fifth, sixth and seventh transient voltage surge suppressors electrically connected between;

said second line-side system phase terminal and said second line-side system neutral terminal;

said second line-side system phase terminal and said line-side system, ground terminal;

said third line-side system, phase terminal and said third line-side system, neutral terminal; and

said third line-side system phase terminal and said line-side system ground terminal, whereby all three modes related to all three AC phases are both ground fault and surge suppression protected.

7. A method for detecting ground faults and maintaining a voltage clamp at a phase side of a ground fault circuit interrupt system which is electrically connected between an AC source and an electrical load such that AC flowing through said system is reliably clamped to a maximum voltage and reliably interrupted upon detection of an interrupt condition by a ground fault circuit interrupt device contained therein, comprising the steps of:

maintaining a voltage clamping function between each of;

phase to neutral, phase to ground and neutral to ground conductors at a phase side input to said system;

detecting a first amount of AC flowing from said AC source to said load utilizing said ground fault circuit interrupt device;

detecting a second amount of AC flowing from said load to said AC source utilizing said ground fault circuit interrupt device;

generating a difference signal indicative of a difference between said first and second amounts of AC;

comparing said difference signal to a reference signal which is proportional to a maximum allowable system current flow difference and defining an interrupt condition in response thereto; and

interrupting said flow of AC upon occurrence of said condition.

8. A ground fault circuit interrupt system which includes auxiliary surge suppression capability, comprising:

a housing including a receptacle for creating an electrical path from said system to each of a phase, neutral and ground conductor; and

a ground fault circuit interrupter disposed in said housing for conditionally coupling said path to each of a phase, neutral and ground terminal of an AC source, said GFCI system including first, second and third transient voltage suppression devices electrically coupled across said phase and neutral conductors, said phase and ground conductors and said neutral and ground conductors such that said system performs both a ground fault circuit interrupt function and a transient voltage surge suppression function.