Method and system for detecting miswiring of a power supply for a domestic appliance

Patent metadata

Field	Value
Publication number	US-10109996-B2
Application number	US-201615062664-A
Country	US
Kind code	B2
Filing date	Mar 7, 2016
Priority date	Mar 7, 2016
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

A system for detecting miswiring in an AC power supply for an appliance may comprise a voltage sensor sensing the voltage of a first hot line of the power supply for powering light electrical loads, a phase sensor sensing the phase difference between the first and a second hot line powering heavy electrical loads therebetween, and a control module coupling to the phase and voltage sensors. The control module may identify a first fault condition indicating that the second hot line and a neutral line are reversed when the voltage of the first hot line exceeds a threshold, and may identify a second fault condition indicating that the first hot line and the neutral line are reversed when the phase signal is within a phase threshold measured from 0 degrees. The system may disconnect different electrical loads from the power supply in the first and the second fault conditions.

First claim

What is claimed is:

1. A system for detecting miswiring in an alternating-current (AC) power supply having a first hot line, a second hot line, and a neutral line, for an appliance having a light electrical load powerable between the first hot line and the neutral line, and a heavy electrical load powerable between the first and the second hot lines, the system comprising:
a voltage sensor configured to send a voltage signal representative of a potential difference between the first hot line and the neutral line;
a phase sensor configured to send a phase signal representative of a phase difference between the first hot line and the second hot line;
a control module coupled to receive the voltage signal and the phase signal and identify a first fault condition indicating that the second hot line and the neutral line are reversed when the voltage signal exceeds a nominal voltage of the first hot line by a voltage threshold, and to identify a second fault condition indicating that the first hot line and the neutral line are reversed when the phase signal is within a phase threshold measured from 0 degrees; and
wherein when the appliance is connected to the AC power supply, the system is configured to disconnect the heavy electrical load and the light electrical load from the AC power supply in the first fault condition; and to disconnect only the heavy electrical load from the AC power supply in the second fault condition.

2. The system of claim 1 , wherein the control module is configured to send an alert signal in at least one of the first fault condition and the second fault condition.

3. The system of claim 1 , wherein the nominal voltage is approximately 120 volts and the voltage threshold is at least approximately 20 volts.

4. The system of claim 1 , wherein the phase threshold is at least approximately 50 degrees.

5. The system of claim 1 , wherein the power supply is one of a 240 volt split-phase system and a 208 volt three-phase system.

6. The system of claim 1 , wherein the voltage signal does not exceed a sum of the nominal voltage and the voltage threshold in the second fault condition.

7. The system of claim 1 , wherein the phase sensor comprises a first zero-crossing detector sensing the voltage of the first hot line relative to the neutral line, and further comprises a second zero-crossing detector sensing the voltage of the second hot line relative to the neutral line.

8. The system of claim 7 , wherein the system is configured to connect the heavy and the light electrical loads to the AC power supply in a third fault condition when there is no zero crossing sensed by the second zero-crossing detector and when the voltage signal does not exceed the nominal voltage by the voltage threshold, the third fault condition indicating that the second hot line supply is either disconnected from the appliance or tied to the neutral line.

9. The system of claim 1 , wherein the control module is contained within the appliance.

10. The system of claim 1 , wherein the control module includes the voltage sensor and the phase sensor and is interposed between the appliance and the AC power supply.

11. The system of claim 1 , further comprising a relay each for disconnecting the light electrical load and the heavy electrical load from the power supply, the relay controllable by the control module.

12. A method for detecting miswiring in an alternating-current (AC) power supply having a first hot line, a second hot line, and a neutral line, for an appliance having a light electrical load powerable between the first hot line and the neutral line, and a heavy electrical load powerable between the first and the second hot lines, the method comprising:
collecting a voltage signal representative of a potential difference between the first hot line and the neutral line;
collecting a phase signal representative of a phase difference between the first hot line and the second hot line;
detecting a first fault condition indicating that the second hot line and the neutral line are reversed when the voltage signal exceeds a nominal voltage of the first hot line by a voltage threshold;
detecting a second fault condition indicating that the first hot line and the neutral line are reversed when the phase signal is within a phase threshold measured from 0 degrees; and
disconnecting the heavy electrical load and the light electrical load from the AC power supply in the first fault condition when the appliance is connected to the AC power supply and disconnecting only the heavy electrical load from the AC power supply in the second fault condition when the appliance is connected to the AC power supply.

13. The method of claim 12 , further comprising sending an alert signal in at least one of the first fault condition and the second fault condition.

14. The method of claim 12 , wherein the nominal voltage is approximately 120 volts and the voltage threshold is at least approximately 20 volts.

15. The method of claim 12 , wherein the phase threshold is at least approximately 50 degrees.

16. The method of claim 12 , wherein the power supply is one of a 240 volt split-phase system and a 208 volt three-phase system.

17. The method of claim 12 , wherein the voltage signal does not exceed a sum of the nominal voltage and the voltage threshold in the second fault condition.

18. The method of claim 12 , wherein the phase difference is determined by measuring a first zero-crossing of the first hot line relative to the neutral line and measuring a second zero-crossing of the second hot line relative to the neutral line, the difference between the first and second zero-crossings determining the phase difference.

19. The method of claim 18 , further comprising:
detecting a third fault condition when no second zero crossing is detected and when the voltage signal does not exceed the nominal voltage by the voltage threshold, the third fault condition indicating that the second hot line of the power supply is either disconnected from the appliance or tied to the neutral line of the power supply; and
connecting the heavy and the light electrical loads to the power supply during the third fault condition indicative of the second hot line being either disconnected from the appliance or tied to the neutral line.

Assignees

• Whirlpool Co

Inventors

• Gigante Alessandro
• Oosterwal Erik P

Classifications

• G01R31/67

  Testing the correctness of wire connections in electric apparatus or circuits · CPC title

• H02H11/002

  in case of inverted polarity or connection; with switching for obtaining correct connection · CPC title

• G01R31/025

  Physics · mapped topic

• H02H3/165 Primary

  for three-phase systems · CPC title

• G01R31/50

  Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections (testing of sparking plugs H01T13/58) · CPC title