Improper voltage detection for electronic circuit breaker

1. A method of tripping a circuit breaker during an improper line-to-neutral voltage condition comprising:

sampling an alternating current (AC) line-to-neutral voltage (“AC line voltage”) at regular intervals during a first time period to generate a plurality of AC line voltage samples;

summing each sample of the set of AC line voltage samples to generate a voltage area value;

determining via a controller whether the voltage area value exceeds a threshold; and

in response to the voltage area value exceeding the threshold,

adding an amount proportional to the voltage area value and determined as a function of the voltage area value to a count value representing excess energy delivered to a load, and

causing a circuit breaker to trip in response to the count value equaling or exceeding a maximum count value.

2. The method of claim 1 , further comprising:

detecting a zero crossing point when the AC line voltage is equal to a neutral voltage; and

wherein the first time period ends approximately when the zero crossing point is detected.

3. The method of claim 1 , wherein adding to the count value an amount determined as a function of the voltage area value comprises:

calculating a trip curve time value corresponding to the voltage area value; and

incrementing the count value by an amount equal to the maximum count value divided by the time value.

4. The method of claim 3 , wherein the trip curve time value corresponding to a voltage area value is selected to be approximately 97.5 seconds−RMS voltage*(0.5 seconds/Volts), wherein the voltage area value is an approximation of RMS voltage.

5. The method of claim 3 , wherein the trip curve time value corresponding to a voltage area value is defined by a function characterized by the ITI-CBEMA RMS Voltage Curve.

6. The method of claim 1 , further comprising:

if voltage area value does not exceed the threshold, decaying the count value by a predetermined amount.

7. The method of claim 1 , wherein the summing includes an integral function.

8. A circuit breaker for breaking a circuit during an improper line-to-neutral voltage condition comprising:

a first circuit configured to receive an alternating current (AC) line-to-neutral voltage (“AC line voltage”) and generate a signal indicative of the AC line voltage; and

a controller coupled to the first circuit configured to:

sample the AC line voltage at regular intervals during a first time period to generate a plurality of AC line voltage samples;

sum each sample of the set of AC line voltage samples to generate a voltage area value;

determine whether the voltage area value exceeds a threshold; and

in response to the voltage area value exceeding the threshold,

add an amount proportional to the voltage area value and determined as a function of the voltage area value to a count representing excess energy delivered to a load, and

cause a circuit breaker to trip in response to the count value equaling or exceeding a maximum count value.

9. The circuit breaker of claim 8 , wherein the controller is configured to:

calculate a trip curve time value corresponding to the voltage area value; and

increment the count value by an amount equal to the maximum count value divided by the time value.

10. The circuit breaker of claim 9 , wherein the trip curve time value corresponding to a voltage area value is selected to be approximately 97.5 seconds−RMS voltage*(0.5 seconds/Volts), wherein the voltage area value is an approximation of RMS voltage.

11. The circuit breaker of claim 8 , further comprising:

a second circuit coupled to the controller, a first AC line input, and a second AC line input configured to output a line-to-line signal representing a line-to-line voltage; and

a third circuit coupled to the controller configured to output a polarity signal representing an identification of the AC line input, of the first AC line input and second AC line input, of negative polarity;

wherein the controller is configured to identify the AC line voltage with the AC line input of negative polarity.

12. The circuit breaker of claim 8 , further comprising:

a zero-crossing detection circuit coupled to the controller configured to output to the controller a zero-crossing signal indicating that the AC line voltage is equal to a neutral voltage;

wherein the first time period ends approximately when the zero crossing point is detected.

13. The circuit breaker of claim 8 , wherein the controller is configured to decay the count value by a predetermined amount if voltage area value does not exceed the threshold.

14. The circuit breaker of claim 8 , wherein the controller is configured to sum each sample of the set of AC line voltage samples using an integral function.

15. In a two-pole circuit breaker, a method of breaking a circuit during an anomalous line-to-neutral voltage condition, the method comprising:

receiving a first alternating current (AC) line-to-neutral voltage (“AC line voltage”);

identifying the polarity of the first AC line voltage;

receiving a second AC line voltage 180 degrees out of phase from the first AC line voltage;

sampling at a first analog input of a controller a line-to-line voltage between the first AC line voltage and the second AC line voltage;

sampling at a second analog input of the controller a first line-to-neutral voltage between the first AC line voltage and a neutral voltage when the polarity of the first AC line voltage is identified as positive; and

calculating at the controller a second line-to-neutral voltage between the second AC line voltage and the neutral voltage using the line-to-line voltage and the first line to neutral voltage;

summing a plurality of samples of the first AC line voltage to generate a voltage area value; and

if the voltage area value indicates that the first AC line voltage is an anomalous voltage, causing a circuit breaker to trip.

16. The method of claim 15 , wherein the anomalous voltage is an undervoltage.

17. The method of claim 15 , wherein the anomalous voltage is an overvoltage.

18. The method of claim 17 , further comprising comparing the first AC line voltage to a trip curve function.