CIRCUIT BREAKER MONITOR FOR UNINTERRUPTABLE POWER SYSTEMS INCLUDING A STATIC BYPASS

• US 3,714,452 A
• Filed: 02/07/1972
• Issued: 01/30/1973
• Est. Priority Date: 02/07/1972
• Status: Expired due to Term

• Current Assignee: Dennis F. Williamson
• Original Assignee: Dennis F. Williamson
• Inventors: Williamson, Dennis F.
• Primary Examiner(s): Duggan, D. F.
• Assistant Examiner(s): Fendelman, Harvey
• Application Number:
  US05/224,195
• Time in Patent Office: 358 Days
• Field of Search: 307/64,66,68,86 317/26,335C 340/292 321/12
• US Class Current: 307/86
• CPC Class Codes: H02J 9/062 for AC powered loads

Abstract

An uninterruptable power system including main apparatus for supplying power to a critical bus, the main apparatus includes electromechanical circuit breakers and a static switch. Bypass apparatus is also provided including a static switch to supply power to the critical bus in high-speed response to the actuation of the circuit breaker trip initiating means.

Claims

1. In an electrical system including main apparatus and bypass apparatus for providing A-C power to a critical bus, said bypass apparatus including a first normally nonconductive static switch connected between a supply of A-C power and said bus, said main apparatus including an inverter for converting D-C power into A-C power, a first normally conductive circuit breaker connected between the inverter and a supply of D-C power and means comprising, a second normally conductive static switch in series with a second normally conductive circuit breaker for connecting the inverter to said bus, said circuit breakers including trip initiating means operative when actuated for causing the circuit breakers to become nonconductive, said initiating means being actuated in response to the detection of an abnormality in said main apparatus, the improvement comprising:

switch controlling means operative in high-speed response to the actuation of at least one of said trip initiating means for causing said second static switch to interrupt the flow of power through the main apparatus to said critical bus, and at the same time for causing said first static switch to begin conducting power from said A-C power supply to said bus, whereupon the flow of A-C power to said bus is virtually uninterrupted.

2. The electrical system as specified in claim 1 wherein said circuit breaker trip initiating means includes undervoltage sensitive means which are normally energized to a voltage above a predetermined threshold level in response to relay means monitoring predetermined conditions in said main apparatus, and wherein upon the detection of an abnormality by said relay means the voltage appearing on the undervoltage sensitive devices falls below said threshold level.

3. The electrical system as specified in claim 2 wherein said static switch controlling means comprises means for monitoring the voltage appearing on the circuit breaker undervoltage sensitive means and for causing said second static switch to become nonconductive and said first static switch to become conductive in high-speed response to the voltage on either of the undervoltage sensitive means dropping below the threshold level.

4. The electrical system as specified in claim 3 wherein said main apparatus also includes means for monitoring fuses in the inverter and wherein said static switch conduction controlling means includes means for causing said second static switch to become nonconductive and said first static switch to become conductive in high-speed response to said last mentioned means.