Compressor protection and grid fault detection device

• US 8,228,648 B2
• Filed: 10/25/2011
• Issued: 07/24/2012
• Est. Priority Date: 02/20/2008
• Status: Active Grant

• Current Assignee: Copeland Corporation LLC (Emerson Electric Company)
• Original Assignee: Emerson Climate Technologies Incorporated (Emerson Electric Company)
• Inventors: Jayanth, Nagaraj B., Ramayya, George
• Primary Examiner(s): Leykin, Rita
• Application Number:
  US13/281,078
• Publication Number:
  US 20120039006A1
• Time in Patent Office: 273 Days
• Field of Search: 318/432, 318/434, 361/22, 361/30, 361/31, 361/33, 361/93.5, 361/93.6, 361/93.7, 361/93.8, 361/93.9, 361/95, 361/96, 361/93.1, 361/94.95, 324/500, 324/511, 324/512, 324/522, 340/522, 340/527, 700/297, 700/298
• US Class Current: 361/30
• CPC Class Codes: F25B 2500/19 Calculation of parameters
• CPC Class Codes: F25B 2600/0251 with on-off operation
• CPC Class Codes: F25B 2700/13 Mass flow of refrigerants
• CPC Class Codes: F25B 2700/151 of the compressor motor
• CPC Class Codes: F25B 2700/2115 of a compressor or the drive means therefor
• CPC Class Codes: F25B 49/022 Compressor control arrangements
• CPC Class Codes: G01R 19/10 Measuring sum, difference or ratio
• CPC Class Codes: G01R 19/16538 in AC or DC supplies G01R19/16519 and G01R19/16528 take precedence
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: H02H 7/08 for dynamo-electric motors
• CPC Class Codes: H02H 7/09 against over-voltage; against reduction of voltage; against phase interruption
• CPC Class Codes: H02H 7/20 for electronic equipment for converters H02H7/10; for electric measuring instruments G01R1/36; for dc voltage or current semiconductor regulators G05F1/569; for amplifiers H03F1/52; for electronic switching circuits H03K17/08
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage

Abstract

A compressor monitoring system includes current and voltage monitors, current and voltage averaging modules, a control module, and a switch. The current monitor measures a current drawn by a motor of a compressor. The current averaging module generates first and second average current values based on the current measured by the current monitor. The voltage monitor measures a utility power voltage. The voltage averaging module generates first and second average voltage values based on the voltage measured by the voltage monitor. The control module selectively generates a fault signal when a first ratio is greater than a first predetermined threshold and a second ratio is less than a second predetermined threshold. The first ratio is based on the first and second average current values. The second ratio is based on the first and second average voltage values. The switch deactivates the motor when the fault signal is generated.

Claims

1. A method comprising:

operating at least one component of an air conditioning system in a first state;

detecting an electrical grid fault in response to a comparison of (i) a first average of current drawn by the at least one component and (ii) a second average of the current drawn by the at least one component; and

in response to the detecting of the electrical grid fault,

switching the at least one component from the first state to a second state, wherein the at least one component consumes less power in the second state than in the first state; and

switching the at least one component from the second state to the first state after a predetermined period of time following the detecting of the electrical grid fault.

11. The method of claim 1, wherein the second average is based on values of the current monitored over a first period and wherein the first average is based on values of the current monitored over a second period prior to the first period.

12. The method of claim 1, further comprising detecting the electrical grid fault in response to the second average being a predetermined percentage greater than the first average.

13. The method of claim 1, further comprising detecting the electrical grid fault in response to (i) the second average being a predetermined percentage greater than the first average only when (ii) a voltage supplied to the at least one component has decreased by a second predetermined percentage.

14. The method of claim 1, further comprising monitoring a voltage supplied to the at least one component, wherein:

the first average is based on values of the current collected during a first period of time,

the second average is based on values of the current collected during a second period of time, and

the electrical grid fault is further detected based on a comparison of (i) values of the voltage collected during the first period of time with (ii) values of the voltage collected during the second period of time.

15. The method of claim 1, further comprising interrupting the current to the at least one component in response to the current drawn by the at least one component exceeding a threshold, wherein the threshold is determined based on a peak current measured during startup of the at least one component.

2. A method comprising:

operating at least one component of an air conditioning system in an ON state;

detecting an electrical grid fault in response to a comparison of (i) a first average of current drawn by the at least one component and (ii) a second average of the current drawn by the at least one component; and

in response to the detecting of the electrical grid fault,

switching the at least one component from the ON state to an OFF state; and

switching the at least one component from the OFF state to the ON state after a predetermined period of time following the detecting of the electrical grid fault.

16. The method of claim 2, wherein the second average is based on values of the current monitored over a first period and wherein the first average is based on values of the current monitored over a second period prior to the first period.

17. The method of claim 2, further comprising detecting the electrical grid fault in response to the second average being a predetermined percentage greater than the first average.

18. The method of claim 2, further comprising detecting the electrical grid fault in response to (i) the second average being a predetermined percentage greater than the first average only when (ii) a voltage supplied to the at least one component has decreased by a second predetermined percentage.

19. The method of claim 2, further comprising monitoring a voltage supplied to the at least one component, wherein:

the first average is based on values of the current collected during a first period of time,

the second average is based on values of the current collected during a second period of time, and

the electrical grid fault is further detected based on a comparison of (i) values of the voltage collected during the first period of time with (ii) values of the voltage collected during the second period of time.

20. The method of claim 2, further comprising switching the at least one component to the OFF state in response to the current drawn by the at least one component exceeding a threshold, wherein the threshold is determined based on a peak current measured during startup of the at least one component.

3. A method of operating a component of an air conditioning system, the method comprising:

monitoring an electrical parameter of the component, wherein the electrical parameter is a current drawn by the component;

determining an occurrence of an electrical grid fault based on a comparison of a first average of the current and a second average of the current; and

in response to the occurrence of the electrical grid fault,

actuating a switch to interrupt the current to the component; and

a predetermined period of time after the current is interrupted, actuating the switch to re-supply the current to the component.

4. The method of claim 3, further comprising determining the occurrence of the electrical grid fault based on monitoring of a power factor of the component.

5. The method of claim 3, further comprising determining the occurrence of the electrical grid fault based on monitoring of a voltage supplied to the component.

6. The method of claim 3, wherein the second average is based on values of the current monitored over a first period and wherein the first average is based on values of the current monitored over a second period prior to the first period.

7. The method of claim 3, further comprising determining the occurrence of the electrical grid fault in response to the second average being a predetermined percentage greater than the first average.

8. The method of claim 3, further comprising determining the occurrence of the electrical grid fault in response to (i) the second average being a predetermined percentage greater than the first average only when (ii) a voltage supplied to the component has decreased by a second predetermined percentage.

9. The method of claim 3, further comprising monitoring a voltage supplied to the component, wherein:

the first average is based on values of the current collected during a first period of time,

the second average is based on values of the current collected during a second period of time, and

the occurrence of the electrical grid fault is further determined based on a comparison of (i) values of the voltage collected during the first period of time with (ii) values of the voltage collected during the second period of time.

10. The method of claim 3, further comprising actuating the switch to interrupt the current to the component in response to the current drawn by the component exceeding a threshold, wherein the threshold is determined based on a peak current measured during startup of the component.