Active transfer time delay for automatic transfer switch

• US 8,766,489 B2
• Filed: 08/29/2011
• Issued: 07/01/2014
• Est. Priority Date: 08/29/2011
• Status: Active Grant

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Lathrop, Todd M.
• Primary Examiner(s): Deberadinis, Robert L.
• Application Number:
  US13/219,783
• Publication Number:
  US 20130049476A1
• Time in Patent Office: 1,037 Days
• Field of Search: 307/64, 307/125
• US Class Current: 307/125
• CPC Class Codes: H02J 3/06 Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
• CPC Class Codes: H02J 9/061 for DC powered loads
• CPC Class Codes: H02J 9/066 characterised by the use of dynamo-electric machines H02J9/08 takes precedence

Abstract

An automatic transfer switch includes first and second inputs inputting first and second voltages; a first output outputting a start signal; a first timer timing a first time after the second voltage is available; a second timer delaying for up to a second time before outputting a transfer signal, the second time being reduced by the first time when the second voltage is available; a transfer mechanism selectively electrically connecting one of the inputs to a second output; and a circuit cooperating with the inputs and the transfer mechanism, causing the start signal to be output responsive to the voltages not being available, and causing the transfer mechanism to electrically connect the second input to the second output in response to the transfer signal.

Claims

1. An automatic transfer switch comprising:

a first input structured to input a first voltage from a first power source;

a second input structured to input a second voltage from a second power source;

a first output structured to output a start signal to said second power source;

a first timer structured to time a first time after the second voltage is available;

a second timer structured to delay for less than or equal to a second time before outputting a transfer signal, the second time being reduced to not less than zero by the first time when the second voltage is available;

a second output;

a transfer mechanism structured to selectively electrically connect one of said first input and said second input to said second output; and

a circuit cooperating with said first input, said second input and said transfer mechanism, said circuit being structured to cause the start signal to be output by said first output responsive to the first and second voltages not being available, said circuit also being structured to cause said transfer mechanism to electrically connect said second input to said second output in response to the transfer signal.

2. The automatic transfer switch of claim 1 wherein the second power source is an engine and a generator;

and wherein the first time is between zero and the second time when the engine was already running prior to the first voltage not being available.

3. The automatic transfer switch of claim 2 wherein the generator runs unloaded for a period of time that is the second time of the second timer minus the first time of the first timer.

4. The automatic transfer switch of claim 2 wherein said circuit comprises a third timer structured to delay for a third time;

and wherein said third timer is independent of whether the engine is running or is not running.

5. The automatic transfer switch of claim 2 wherein said circuit comprises a third timer structured to delay for a third time;

and wherein said circuit is further structured to bypass the second timer after the third timer times for the third time when the first voltage is not available and when the second voltage is available for at least as long as the second time.

6. The automatic transfer switch of claim 1 wherein the second time is about 20 seconds.

7. The automatic transfer switch of claim 1 wherein said first power source is a utility power source.

8. The automatic transfer switch of claim 1 wherein said second power source is an engine-generator power source.

9. The automatic transfer switch of claim 1 wherein said circuit comprises a third timer structured to delay for a third time;

wherein the first and second voltages are both not available; and

wherein said circuit is further structured to output the start signal after the third timer delays for the third time.

10. A controller for an automatic transfer switch, said automatic transfer switch comprising a first input structured to input a first voltage from a first power source, a second input structured to input a second voltage from a second power source, a first output structured to output a start signal to said second power source, a second output, and a transfer mechanism structured to selectively electrically connect one of said first input and said second input to said second output, said controller comprising:

a first timer structured to time a first time after the second voltage is available;

a second timer structured to delay for less than or equal to a second time before outputting a transfer signal, the second time being reduced to not less than zero by the first time when the second voltage is available; and

a circuit cooperating with said first input, said second input and said transfer mechanism, said circuit being structured to cause the start signal to be output by said first output responsive to the first and second voltages not being available, said circuit also being structured to cause said transfer mechanism to electrically connect said second input to said second output in response to the transfer signal.

11. The controller of claim 10 wherein the second power source is an engine and a generator;

and wherein the first time is between zero and the second time when the engine was already running prior to the first voltage not being available.

12. The controller of claim 11 wherein the generator runs unloaded for a period of time that is the second time of the second timer minus the first time of the first timer.

13. The controller of claim 11 wherein said circuit comprises a third timer structured to delay for a third time;

and wherein the third timer is independent of whether the engine is running or is not running.

14. The controller of claim 11 wherein said circuit comprises a third timer structured to delay for a third time;

and wherein said circuit is further structured to bypass the second timer after the third timer times for the third time when the first voltage is not available and when the second voltage is available for at least as long as the second time.

15. The controller of claim 10 wherein the second time is about 20 seconds.

16. The controller of claim 10 wherein said first power source is a utility power source.

17. The controller of claim 10 wherein said second power source is an engine-generator power source.

18. The controller of claim 10 wherein said circuit comprises a third timer structured to delay for a third time;

wherein the first and second voltages are both not available; and

wherein said circuit is further structured to output the start signal after the third timer delays for the third time.