Wiring fault correction circuit

• US 7,551,412 B2
• Filed: 05/08/2006
• Issued: 06/23/2009
• Est. Priority Date: 05/09/2005
• Status: Active Grant

• Current Assignee: Electronic Systems Protection Incorporated (Ametek Incorporated)
• Original Assignee: Electronic Systems Protection Incorporated (Ametek Incorporated)
• Inventors: Winch, Peter
• Primary Examiner(s): Paladini; Albert W
• Assistant Examiner(s): PATEL, DHARTI HARIDAS
• Application Number:
  US11/429,435
• Publication Number:
  US 20060268472A1
• Time in Patent Office: 1,142 Days
• Field of Search: None
• US Class Current: 361/42
• CPC Class Codes: H02H 11/002 in case of inverted polarity or connection; with switching for obtaining correct connection

Abstract

A wiring fault correction circuit for determining wiring conditions of an AC supply system includes: input line and neutral conductors connectable to the AC supply system; output line and neutral conductors connectable to a load; first, second, third, and fourth single pole, single throw relays; a first driver circuit for controlling the first and second single pole, single throw relays to respectively connect the input line conductor to the output line conductor and the input neutral conductor to the output neutral conductor in response to a correctly wired AC supply system; and a second driver circuit for controlling the third and fourth single pole, single throw relays to respectively connect the input line conductor to the output neutral conductor and the input neutral conductor to the output line conductor in response to an incorrectly wired AC supply system in which line and neutral conductors are reversed.

Claims

1. A wiring fault correction circuit for determining wiring conditions of an AC supply system, comprising:

input line and neutral conductors configured to be coupled to the AC supply system;

output line and neutral conductors configured to be coupled to a load;

first, second, third, and fourth single pole, single throw relays;

a first driver that controls the first and second single pole, single throw relays to respectively connect the input line conductor to the output line conductor and the input neutral conductor to the output neutral conductor in response to a conectly wired AC supply system, wherein the first driver circuit comprises;

a first diode, a first resistor, and a first capacitor connected in series between the input line conductor and ground;

a switching device having first and second input terminals connected in parallel with the first capacitor and an output terminal coupled to relay coils of the first and second single pole, single throw relays; and

a second resistor connected at one end between the first resistor and the first capacitor and at the other end to the first input terminal of the switching device, wherein the first diode, first capacitor, and first and second resistors supply a leakage current that activates the switching device in response to an AC voltage signal on the input line conductor, whereby the switching device activates the first and second single pole, single throw relays; and

a second driver circuit that controls the third and fourth single pole, single throw relays to respectively connect the input line conductor to the output neutral conductor and the input neutral conductor to the output line conductor in response to an incorrectly wired AC supply system in which line and neutral conductors of the AC supply system are reversed.

2. The circuit of claim 1, wherein:

the first driver circuit comprises a first switching device configured to energize relay coils of the first and second single pole, single throw relays in response to an AC voltage signal on the input line conductor; and

the second driver circuit comprises a second switching device configured to energize relay coils of the third and fourth single pole, single throw relays in response to an AC voltage signal on the input neutral conductor.

3. The circuit of claim 2, wherein the AC voltage signal is a 120 Volt AC signal.

4. The circuit of claim 2, wherein:

the first driver circuit further comprises a first voltage divider circuit connected between the input line conductor and ground and configured to activate the first switching device to energize the relay coils of the first and second single pole, single throw relays in response to an AC voltage signal on the input line conductor; and

the second driver circuit further comprises a second voltage divider circuit connected between the input neutral conductor and ground and configured to activate the second switching device to energize the relay coils of the third and fourth single pole, single throw relays in response to an AC voltage signal on the input neutral conductor.

5. The circuit of claim 2, wherein the first and second switching devices are optical isolator circuits.

6. The circuit of claim 5, wherein the optical isolator circuits comprise photomos relays.

7. The circuit of claim 6, wherein the photomos relays each comprise a light emitting diode and a field effect transistor activated by the light emitting diode in the presence of a leakage current.

8. The circuit of claim 1, further comprising:

a second diode and a third resistor connected in series between the input line conductor and the switching circuit to provide a supply voltage signal to the switching circuit.

9. The circuit of claim 1, wherein the second driver circuit comprises:

a first diode, a first resistor, and a first capacitor connected in series between the input neutral conductor and ground;

a switching device having first and second input terminals connected in parallel with the first capacitor and an output terminal coupled to relay coils of the third and fourth single pole, single throw relays; and

a second resistor connected at one end between the first resistor and the first capacitor and at the other end to the first input terminal of the switching device, wherein the first diode, first capacitor, and first and second resistors supply a leakage current that activates the switching device in response to an AC voltage signal on the input neutral conductor, whereby the switching device activates the third and fourth single pole, single throw relays.

10. The circuit of claim 9, further comprising:

a second diode and a third resistor connected in series between the input line conductor and the switching circuit to provide a supply voltage signal to the switching circuit.

11. An AC power filter circuit, comprising:

the wiring fault correction circuit of claim 1;

a diverter stage configured to suppress transient excess energy;

an electromagnetic interference suppression stage configured to suppress electromagnetic interference; and

a clamping stage configured to suppress residual transient excess energy.