Apparatus, system, and/or method for protection and control of an electrical device

• US 20080094768A1
• Filed: 04/04/2007
• Published: 04/24/2008
• Est. Priority Date: 04/04/2006
• Status: Active Grant

• Current Assignee: Cerus Industrial Corporation
• Original Assignee: Cerus Industrial Corporation
• Inventors: Perra, Andre, Holce, Kent, Cota, Roger
• Granted Patent: US 8,300,372 B2
• Time in Patent Office: Days
• US Class Current: 361/79
• CPC Class Codes: A61K 31/53 having six-membered rings with three nitrogens as the only ring hetero atoms, e.g. chlorazanil, melamine melarsoprol A61K31/555 ; with four nitrogen atoms A61K31/495

Abstract

An electrical device protection apparatus, such as an overload relay, can include a microprocessor 102 that can receive a wide range of current signals from a current transformer or other current sensor. Also microprocessor 102 can employ a voltage sensor 112 to measure line voltage, for representing true power, and as a power supply 114 source for the microprocessor 102. The microprocessor can then generate annunciation signals 118, control signals 120, and/or communication signals 122 as necessary for the control and/or protection of an attached electrical device.

Claims

1. An apparatus for protection and control of an electrical device, comprising:

a current transformer provisioned for measuring current supplied to an electrical device with substantial accuracy over a wide current range; and

a microprocessor configured for;

receiving a current input signal corresponding to the current measured by the current transformer;

receiving a voltage input signal corresponding to a voltage measured from a power supply powering the electrical device;

identifying a classification of the electrical device, based, at least in part, on at least one of the received current input signal or the received voltage input signal; and

implementing control logic to set a set point for operating the electrical device consistent with the identified classification.

2. The apparatus of claim 1, wherein the microprocessor derives operating power from the power supply powering the electrical device.

3. The method of claim 1, wherein the microprocessor identifies the classification of the electrical device by comparing an in-rush current to a full load current for the electrical device.

4. The method of claim 1, wherein the microprocessor identifies the classification of the electrical device based, at least in part, on a phase-angel load characteristic.

5. The method of claim 1, wherein the microprocessor is programmed to discern loss of load to the electrical device in response to detecting rapid changes in amperage or power.

6. The method of claim 1, wherein the microprocessor is configured to send an interrogation signal to the electrical device and, in response to sending the interrogation signal, receive a return signal or identify a circuit characteristic for use in identifying the classification of the electrical device.

7. The apparatus of claim 1, wherein the current transformer is constructed of a material substantially resistant to core saturation.

8. The apparatus of claim 7, wherein the material is non-magnetic.

9. The apparatus of claim 1, wherein the current transformer is a Rogowski current transformer.

10. The apparatus of claim 9, wherein the Rogowski current transformer is printed on a printed circuit board.

11. The apparatus of claim 10, wherein the microprocessor is mounted to the printed circuit board.

12. The apparatus of claim 8, wherein the Rogowski current transformer is torroidally wound over a cylindrically shaped core so as to enhance signal gain for low current applications.

13. The apparatus of claim 8, further comprising a differential noise canceling loop circuit to substantially resist electromagnetic interference and enable accurate current measurement at a low current input value.

14. The apparatus of claim 13, wherein the low current input values correspond to a current below 1 Ampere.

15. The apparatus of claim 1, wherein the wide current range corresponds to a range substantially between 0.1-40 Amperes.

16. The apparatus of claim 1, further comprising an analog to digital converter.

17. The apparatus of claim 16 wherein the analog to digital converter is an 18-bit converter.

18. The apparatus of claim 17, wherein the analog to digital converter is a 10-bit converter.

19. The apparatus of claim 18, further comprising a pre-scaler circuit element to scale a signal input to the analog to digital converter.

20. The apparatus of claim 19, wherein the pre-scaler is a digital potentiometer or pulse width modulator.

21. The apparatus of claim 1, further comprising at least one manual control to limit the current transformer to measuring within an expected subset current range, the expected subset current range being a limited range within the wide current range.

22. The apparatus of claim 1, further comprising a latching contact relay.

23. The apparatus of claim 1, further comprising voltage input pins provisioned in conjunction with current transformer apertures for connection to a secondary control device.

24. The apparatus of claim 23, wherein the secondary control device is a mechanical contactor.

25. A method, comprising the steps of:

measuring at least one of an input signal or circuit characteristic of a power distribution circuit electromagnetically connected to an electrical device;

based at least in part on the measured input signal or circuit characteristic, classifying the electrical device; and

setting a control parameter for the electrical device based at least in part on the classification of the electrical device.

26. The method of claim 25, wherein the measuring step includes measuring a load characteristic of the electrical device.

27. The method of claim 26, wherein the load characteristic includes in-rush current.

28. The method of claim 26, wherein the load characteristic includes a phase-angle.

29. The method of claim 25, wherein

the measuring step includes sending an interrogation signal and either receiving a response signal or detecting a circuit characteristic;

and

the classifying step is based, at least in part, on the received response signal or detected circuit characteristic.

30. The method of 25, further comprising the step of drawing operating power from a line power source supplying power to the power distribution circuit, the operating power being used for conducting the measuring, classifying, and setting steps.

31. A system for controlling and protecting an electrical device, comprising:

a power source providing power to an electrical device;

a contactor relay for disconnecting power to the electrical device in response to undesirable operating condition being measured in the electrical device; and

an electrical device protection relay including;

a current transformer for measuring current to the electrical device;

a microprocessor for identifying the electrical device and setting one or more corresponding control parameters to detect an occurrence of the undesirable operating condition in the electrical device.

32. The system of claim 31 wherein the electrical device protection relay is an overload relay.

33. The system of claim 31, wherein the undesirable operating condition is an overload on the electrical device.

34. The system of claim 31, wherein the undesirable operating condition is an under load on the electrical device.

35. The system of claim 31, wherein the undesirable operating condition is an overload or an under load on the electrical device.

36. The system of claim 31, wherein the contactor relay and electrical device protection relay are provisioned in a single housing.

37. The system of claim 36, wherein the common housing corresponds to a starter mechanism for the electrical device.