Hall plate wattmeter circuit including compensation for the hall plate thermo-voltage

Claim 1

APPARATUS FOR MEASURING THE ELECTRICAL POWER SUPPLIED TO A LOAD CIRCUIT FROM A SOURCE OF VOLTAGE, COMPRISING WINDING MEANS COUPLED TO SAID LOAD CIRCUIT FOR PRODUCING A MAGNETIC FIELD DETERMINED BY THE MAGNITUDE OF THE LOAD CURRENT, A HALL PLATE MOUNTED IN SAID MAGNETIC FIELD COMPRISING CURRENT INPUT TERMINALS AND OUTPUT TERMINALS ACROSS WHICH A HALL VOLTAGE AND A THERMAL VOLTAGE ARE DEVELOPED, SAID THERMAL VOLTAGE BEING VARIABLE WITH THE VALUE OF CURRENT FLOWING THROUGH SAID CURRENT INPUT TERMINALS, MEANS FOR COMPENSATING THE THERMAL VOLTAGE VARIATIONS OF SAID HALL PLATE COMPRISING A THERMOCOUPLE ELEMENT HAVING A HEATER ELEMENT SERIALLY CONNECTED WITH SAID HALL PLATE CURRENT INPUT TERMINALS, AN ENERGIZING CIRCUIT COUPLED TO SAID LOAD CIRCUIT FOR SUPPLYING A CURRENT TO SAID PLATE INPUT TERMINALS AND SAID HEATER ELEMENT TO SAID TO THE LOAD VOLTAGE, SAID THERMOCOUPLE ELEMENT FURTHER COMPRISING A PAIR OF OUTPUT ELECTRODES FOR SUPPLYING A THERMAL VOLTAGE DETERMINED BY THE VALUE OF SAID HEATER CURRENT, INDICATING MEANS, AND MEANS FOR COUPLING THE VOLTAGE DEVELOPED ACROSS SAID HALL PLATE OUTPUT TERMINALS AND THE TERMAL VOLTAGE OF SAID THERMOCOUPLE OUTPUT ELECTRODES TO SAID INDICATING MEANS IN OPPOSITION.