Method and apparatus for transferring between electrical power sources which adaptively blocks transfer until load voltage decays to safe value

• US 5,635,772 A
• Filed: 10/25/1995
• Issued: 06/03/1997
• Est. Priority Date: 10/25/1995
• Status: Expired due to Term

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: McGill, James W., Lagree, James L., Hanna, James R.
• Primary Examiner(s): Martin, David S.
• Assistant Examiner(s): Paladini, Albert W.
• Application Number:
  US08/547,888
• Time in Patent Office: 587 Days
• Field of Search: 307/43, 307/64, 307/80, 307/81, 307/87, 307/67, 307/89, 307/90, 304/492, 363/35, 363/36, 363/21, 361/2, 361/3, 361/5, 361/415, 361/159
• US Class Current: 307/64
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

Transfer between alternative electrical power sources for highly inductive loads, such as motors, is made using an open transition with the load connected to the new source only after the voltage on the load bus has fallen below a predetermined value, preferably a value which is about 30% or less of the nominal source voltage.

Claims

1. A method of transferring a highly inductive load from one electric power source to another electric power source, said method comprising the steps of:

disconnecting the highly inductive load from said one electric power source;

monitoring residual voltage on said highly inductive load; and

connecting the highly inductive load to said another electric power source only after said residual voltage on the highly inductive load has decayed to at least a predetermined value.

2. The method of claim 1 wherein said another power source has a nominal voltage, and said step of connecting comprises connecting said highly inductive load to said another power source only after said residual voltage on the highly inductive load has decayed to a predetermined value which is equal to or less than about 30% of said nominal voltage.