System powered power supply using dual transformer HVAC systems

• US 5,352,930 A
• Filed: 08/27/1993
• Issued: 10/04/1994
• Est. Priority Date: 03/27/1991
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Ratz, James W.
• Primary Examiner(s): Pellinen, A. D.
• Assistant Examiner(s): Fleming, Fritz M.
• Application Number:
  US08/112,274
• Time in Patent Office: 403 Days
• Field of Search: 307/17, 307/43, 307/68, 307/36, 307/82, 307/83, 307/39, 363/70, 165/26
• US Class Current: 307/43
• CPC Class Codes: G05F 1/577 for plural loads

Abstract

A power supply to supply power to a secondary system. The power supply is adapted to receive power from a plurality of primary systems. The power supply having a first rectifier which supplies power to the secondary system from a first primary system. At least one isolated rectifier which is connected to a primary system other than the first primary system. Wherein the primary system other than the first primary system provides power to the isolated rectifier. A power supply means connected to the first rectifier and the isolated rectifier. Wherein the rectifier and the isolated rectifier provide power to the power supply and the power supply provides power to the secondary system. Wherein due to the characteristic of the isolated rectifier, it is not possible to connect the first primary system out of phase with the primary system other than the first primary system, thereby eliminating unsafe voltages.

Claims

1. A power supply for a thermostat, the thermostat for controlling a heating system and a cooling system, said power supply receiving power from the heating system and the cooling system, the heating system and the cooling system being powered by separate A.C. power sources, said power supply comprising:

a first diode bridge electrically connected to the heating system, said first diode bridge having two input nodes and first and second output nodes wherein said heating system is electrically connected to said input nodes of said first diode bridge;

a second diode bridge electrically connected to the cooling system, said second diode bridge having two input nodes and first and second output nodes, wherein said cooling system is electrically connected to said input nodes of said second diode bridge;

means for providing power to said thermostat, having a current limiter and a power supply means, said first output node of said first diode bridge electrically connected to said first output node of said second diode bridge, said second output node of said first diode bridge electrically connected to said second output node of said second diode bridge, said first output node of said first diode bridge electrically connected to said current limiter, said second output node of said first diode bridge electrically connected to said power supply means, said current limiter electrically connected to said power supply means, wherein said power supply means converts rectified power from said first diode bridge and said second diode bridge to D.C. power to power the thermostat, wherein said first diode bridge and said second diode bridge electrically isolate said heating system and said cooling system;

an isolation transformer electrically connected between said input nodes of said first diode bridge and said heating system; and

first and second switch means, said first switch means electrically connected across said input nodes of said first diode bridge, said second switch means electrically connected across said input nodes of said second diode bridge, wherein said first and said second switch means activate said heating and cooling systems respectively.

2. A power supply for a thermostat, the thermostat for controlling a heating system and a cooling system, said power supply receiving power from the heating system and the cooling system, the heating system and the cooling system being powered by separate A.C. power sources, said power supply comprising:

a first diode bridge electrically connected to the heating system, said first diode bridge having two input nodes and first and second output nodes wherein said heating system is electrically connected to said input nodes of said first diode bridge;

a second diode bridge electrically connected to the cooling system, said second diode bridge having two input nodes and first and second output nodes, wherein said cooling system is electrically connected to said input nodes of said second diode bridge;

means for providing power to said thermostat, having a current limiter and a power supply means, said first output node of said first diode bridge electrically connected to said first output node of said second diode bridge, said second output node of said first diode bridge electrically connected to said second output node of said second diode bridge, said first output node of said first diode bridge electrically connected to said current limiter, said second output node of said first diode bridge electrically connected to said power supply means, said current limiter electrically connected to said power supply means, wherein said power supply means converts rectified power from said first diode bridge and said second diode bridge to D.C. power to power the thermostat, wherein said first diode bridge and said second diode bridge electrically isolate said heating system and said cooling system;

an isolation transformer electrically connected between said input nodes of said second diode bridge and said cooling system; and

first and second switch means, said first switch means electrically connected across said input nodes of said first diode bridge, said second switch means electrically connected across said input nodes of said second diode bridge, wherein said first and said second switch means activate said heating and cooling systems respectively.