Compressor protection and diagnostic system

• US 8,475,136 B2
• Filed: 01/11/2010
• Issued: 07/02/2013
• Est. Priority Date: 12/30/2003
• Status: Active Grant

• Current Assignee: Copeland Corporation LLC (Emerson Electric Company)
• Original Assignee: Emerson Climate Technologies Incorporated (Emerson Electric Company)
• Inventors: Jayanth, Nagaraj
• Primary Examiner(s): Freay, Charles
• Assistant Examiner(s): GATZEMEYER, RYAN JON
• Application Number:
  US12/685,375
• Publication Number:
  US 20100111709A1
• Time in Patent Office: 1,268 Days
• Field of Search: 417/44.11, 417/12, 417/63, 417/410.5, 310/68.B, 310/68.C, 310/71, 318432-434
• US Class Current: 417/44.11
• CPC Class Codes: F04B 49/06 Control using electricity regulating by means of floats actuating electric switches F04B49/04
• CPC Class Codes: F04C 18/0215 where only one member is moving
• CPC Class Codes: F04C 2240/803 Electric connectors or cables; Fittings therefor
• CPC Class Codes: F04C 2270/80 Diagnostics
• CPC Class Codes: F04C 23/008 Hermetic pumps
• CPC Class Codes: F04C 28/28 Safety arrangements; Monitoring
• CPC Class Codes: H01R 13/6683 with built-in sensor
• CPC Class Codes: H02H 3/006 Calibration or setting of parameters
• CPC Class Codes: H02H 3/08 responsive to excess current responsive to abnormal temperature caused by excess current H02H5/04
• CPC Class Codes: H02H 3/085 making use of a thermal sensor, e.g. thermistor, heated by the excess current also responsive to the temperature of the protected device H02H5/041, thermal images H02H6/00
• CPC Class Codes: H02H 5/041 additionally responsive to excess current H02H5/048 takes precedence
• CPC Class Codes: H02H 7/08 for dynamo-electric motors
• CPC Class Codes: Y10S 417/902 Hermetically sealed motor pump unit

Abstract

A compressor includes at least one current sensor and processing circuitry in communication with the at least one current sensor. The processing circuitry declares a locked rotor condition when current drawn by the compressor is at least forty percent of peak locked rotor current.

Claims

1. A compressor comprising:

at least one current sensor; and

processing circuitry in communication with said at least one current sensor and operable to declare a locked rotor condition when current drawn by the compressor is at least forty percent of peak locked rotor current, said processing circuitry recording said peak locked rotor current as a highest current reading taken during a predetermined time period following start up of the compressor.

2. The compressor of claim 1, wherein said predetermined time period is equal to about one-hundred milliseconds.

3. The compressor of claim 1, further comprising a power interruption system in communication with said processing circuitry, said processing circuitry instructing said power interruption system to restrict power to the compressor if said locked rotor condition is determined.

4. The compressor of claim 1, wherein said processing circuitry issues a warning when said locked rotor condition is determined.

5. The compressor of claim 1, wherein said processing circuitry issues an alarm after a predetermined number of locked rotor conditions are determined.

6. The compressor of claim 1, wherein said processing circuitry is operable to declare a no three phase power alarm when a compressor demand input is read high for a predetermined time period in any one of a series of current transformer inputs.

7. The compressor of claim 6, wherein said predetermined time period is about two seconds.

8. The compressor of claim 6, wherein said alarm is reset if current is detected in any of the current transformer inputs or said compressor demand is read low for said predetermined time period.

9. The compressor of claim 1, wherein said processing circuitry sends a diagnostic signal to a diagnostic output to record the locked rotor fault.

10. The compressor of claim 1, wherein said at least one current sensor is a current transformer.

11. A method comprising:

starting a motor of a compressor;

recording current drawn by said motor for a first predetermined time period following said starting;

comparing the highest current drawn by said motor during said first predetermined time period to running current drawn by said motor following said first predetermined time period; and

determining whether said running current exceeds at least forty percent of said highest current.

12. The method of claim 11, wherein recording said current for said first predetermined time period includes recording said current for about one hundred milliseconds.

13. The method of claim 11, further comprising reading said current drawn by said motor following a second predetermined time period after said starting if said highest current exceeds a threshold value.

14. The method of claim 13, wherein said threshold value is equal to about three hundred Amps.

15. The method of claim 13, wherein said second predetermined time period is about eight hundred milliseconds.

16. The method of claim 13, further comprising declaring a seizure of said motor if said running current exceeds said highest current after said second predetermined time period.

17. The method of claim 16, further comprising interrupting power to said motor if said seizure is detected.

18. The method of claim 11, further comprising reading said current drawn by said motor following a second predetermined time period after said starting if said highest current is less than a threshold value.

19. The method of claim 18, wherein said threshold value is equal to about three hundred Amps.

20. The method of claim 18, wherein said second predetermined time period is about eight hundred milliseconds.

21. The method of claim 18, further comprising interrupting power to said motor if said running current is not less than about forty percent of said highest current after said second predetermined time period.

22. The method of claim 11, wherein said recording current drawn by said motor includes using a current transformer to record said current drawn by said motor.

23. The method of claim 11, further comprising declaring a locked rotor condition when said running current exceeds at least forty percent of said highest current.