US PATENT SUBCLASS 431 / 78
.~.~.~ By electrical control circuit

Current as of: June, 1999
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431 /   HD   COMBUSTION

18  DF  TIMER, PROGRAMMER, RETARDER OR CONDITION RESPONSIVE CONTROL {26}
75  DF  .~ By combustion or combustion zone sensor {2}
77  DF  .~.~ Of shutdown by response to sensed combustion failure or overheat {4}
78.~.~.~ By electrical control circuit {2}
79  DF  .~.~.~.~> Photoelectric sensor
80  DF  .~.~.~.~> Thermoelectric generator sensor

DEFINITION

Classification: 431/78

(under subclass 77) Apparatus in which the combustion terminating structure includes electrical means.

SEE OR SEARCH THIS CLASS, SUBCLASS:

24+, for a shutdown control including an electrical test circuit sensing malfunction of a combustion sensing circuit.

59, for an electrical or magnetic sensor of a first burner controlling a second burner.

66, for a system in which a sensor of the electrical condition or temperature of an igniter controls the feed of fuel.

SEE OR SEARCH CLASS

307, Electrical Transmission or Interconnection Systems, 117, for a residual electrical interconnection system responsive to light, heat, vibratory or radiant energy.

323, Electricity: Power Supply or Regulation Systems,

294, for a residual electrical control in which an impedance responsive to a thermal condition is between the electrical source and the load.

331, Oscillators,

66, for an electrical system including an oscillator and a useful output for the oscillator and in which means responsive to temperature, or radiant energy in the form of light modifies a current characteristic of the oscillator.

338, Electrical Resistors,

22+, for an electrical resistance variable in response to temperature changes.

340, Communications: Electrical,

577+, for a flame responsive indicating system; and subclasses 584+ for a temperature responsive indicating system.

361, Electricity: Electrical Systems and Devices,

161+, 170+, and 211 for a thermally controlled electrical circuit for a relay or electromagnet. 374, Thermal Measuring and Testing,

179+, for a current generating sensor or thermometer, per se.