Watt-hour counter

• US 3,986,114 A
• Filed: 05/29/1975
• Issued: 10/12/1976
• Est. Priority Date: 05/29/1975
• Status: Expired due to Term

• Current Assignee: Firetrol, Inc.
• Original Assignee: Firetrol, Inc.
• Inventors: Hare, John E.
• Primary Examiner(s): Krawczewicz, Stanley T.
• Application Number:
  US05/581,617
• Time in Patent Office: 502 Days
• Field of Search: 324/94, 324/182, 194/11, 194/9 T
• US Class Current: 324/94
• CPC Class Codes: G01R 21/00 Arrangements for measuring electric power or power factor G01R7/12 takes precedence
• CPC Class Codes: G01R 21/007 Adapted for special tariff measuring G01R21/01, G01R21/02, G01R21/08, G01R21/10, G01R21/1278 and G01R21/1333 take precedence
• CPC Class Codes: G07F 15/003 for electricity

Abstract

A watt-hour counter for supplying electrical energy at a remote location from an external power source having a housing with a connection to an external source of electrical power, at least one electrical output mounted externally in the housing and a current measuring means serially connected between the external power source and the electrical output, for producing an output potential proportional to the current at the electrical output. A rechargeable coulometer is coupled to the output of the current measuring means, so that the current sensing means removes a predetermined magnitude of charge from the coulometer proportional to the ampere-seconds used in the external power lines. There is also a charging circuit coupled to the coulometer for charging the coulometer with a predetermined charge, and a switch means serially connected between the external power source and the output, and coupled to the coulometer for interrupting the power to the output in response to a change in potential of the coulometer.

Claims

1. A watt-hour counter for supplying electrical energy at a remote location from an external power source comprising:

a housing having a connection to an external source of electrical power;

at least one electrical output mounted externally in said housing;

current measuring means serially connected between the external power source and said electrical output, for producing an output potential proportional to the current in said electrical output;

a rechargeable coulometer coupled to the output of said current measuring means, said current measuring means removing a predetermined magnitude of charge from said coulometer proportional to the ampere-seconds used in said external power lines;

a charging circuit coupled to said coulometer for charging said coulometer with a predetermined charge; and

switch means serially connected between said external power source and said output and coupled to said coulometer for interrupting the power to the output in response to a change in potential of said coulometer.

2. The watt-hour counter as recited in claim 1 wherein said current measuring means comprises a resistor placed in series in said external power line and a potential sensing means coupled across said resistor for providing a DC potential to said coulometer proportional to the voltage drop across said resistor.

3. The watt-hour counter as recited in claim 2 wherein said potential sensing means comprises an illumination device for producing a light intensity proportional to the voltage drop across said resistor, and photoconductive means for producing an output poential proportional to the illumination of said lamp.

4. The watt-hour counter as recited in claim 1 wherein said current measuring means comprises a current transformer for producing an output potential proportional to the magnitude of current in said external line.

5. The watt-hour counter as recited in claim 2 wherein said charging circuit comprises a timer having a variable resistance for selecting different rates of charge to be applied to said coulometer.

6. The watt-hour counter as recited in claim 1 wherein said switch means comprises a triac serially connected between said external power source and the output, and a trigger circuit coupling said triac to said coulometer so that a change of potential in said coulometer will interrupt the external power source.

7. The watt-hour counter as recited in claim 1 additionally comprising a coin-operated mechanism coupled to said charging circuit for applying a charge to said coulometer proportional to the number of coins inserted in said coin-operated mechanism.

8. The watt-hour counter as recited in claim 1 wherein said switch means comprises a relay serially connected between said external power source and the output of said meter, and a relay driver coupling said coulometer to said relay.

9. The watt-hour counter as recited in claim 1 wherein said coulometer comprises an E-cell.