Other

General Electric Company

Harris Semiconductor Patents Inc.

Peter J Carlson

Robert G Hodgins

Ram Rajagopalan

A method and apparatus measured and calculates the derived thermodynamic state of a heat-pump or air conditioning system using information from transducers sensing elementary thermodynamic variables in the system. Elementary signals such as pressure, temperature, power, humidity, air flow, and others as required are derived using transducers from closed and open portions of the thermodynamic system, and which signals are then transmitted using appropriate transmission media. These signals are input to a computer, which could take many forms (electrical analog, electrical digital, pneumatic, hydraulic, and others), and these signal inputs along with known and tabulated thermodynamic characteristics of the working fluid (refrigerant) and psychrometric properties of the cooled media (air for example), are used to calculate thermodynamic output variables such as entropy, enthalpy, pressure, temperature, and volume at various states in the thermodynamic cycle. The output variables can be presented in tabulated or graphic form for clear understanding such as pressure vs. volume, temperature vs. entropy, or pressure vs. enthalpy graphs of the working system. The derived data can be used to determine efficiency and operating condition of the heat-pump or air-conditioning system and can be used as an aid in the diagnosis of the cause of a malfunctioning or inefficient system. Using artificial intelligence in an 'expert' system, diagnosis could be completely automated.

Method and apparatus for diagnosing problems with the thermodynamic

The junction temperature rise of a power MOSFET serially connected to a lamp whose resistance nonlinearly increases during turn-on is moderated by the use of control circuitry which initially sets up a relatively low essentially constant current flow through the lamp and transistor and then automatically after the lamp resistance reaches a preselected level, the lamp is allowed to draw significantly more current. The size and therefore cost of the power MOSFET is reduced significantly because the magnitude of the current spike generated by turning on the lamp is significantly reduced the use of the novel control circuitry.

Soft start solid state switch

Damping resistance is introduced via transformer coupling into a circuit which includes an inductance-capacitance (LC) filter arrangement to smooth the current pulses applied to a load.

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Raleigh, NC, United States of America

Peter J Carlson