The Babcock & Wilcox Company

Elsag International B.v.

Gas Research Institute

John J Fry

Robert A Smith

George R Hall, Ii

John W Robertson, Jr

Edward Bastijanic

Gordon D Woolbert

David F Ross

Daniel C Barnett

An industrial process oxygen analyzer, and method of using same, incorporates an automotive oxygen sensor to minimize the criticalness of controlling heater temperature during operation. Higher sensor heater temperature, required to accommodate the automotive oxygen sensor, is achieved by application of higher supply voltage to the sensor heater. Current limiting of the heater supply circuit reduces stress on the sensor heater, even at the higher operating temperature.

Automotive oxygen sensor for use in an industrial process analyzer

An arrangement for providing radio frequency and electromagnetic interference protection to at least part of circuitry mounted on a circuit board comprises alternating slots and bridges which form a boundary between a protected area of the circuit board and an unprotected area of the circuit board. The circuit portions which require protection are mounted in the protected area and are covered by a top cover having fingers which extend through the slots. Connecting lines between the protected and unprotected portions of the circuit portions extend along the bridges between the slots. A bottom cover engages under the protected area and mates to the top cover for providing electromagnetic interference protection for the circuit portions within the protected area.

Method for RFI/EMI protection of electronic circuitry

An apparatus for measuring differential impedances which incorporates a CMOS timer in place of the sine wave generator in a typical AC bridge configuration. A toroidal signal transformer having its primary and secondary windings tightly twisted together and wound around the core lessens temperature drift characteristics. The differential bipolar current signal provided by the secondary winding is passed through an AC to DC converter which is switched by a field effect transistor, thereby eliminating the need for prior art inverter comparator circuits. Finally, by use of a bandpass filter after the signal transformer and by insertion of a capacitor before the AC to DC converter, the need for the active filter stage used in the prior art is eliminated.

Apparatus for measuring differential impedances

Method of applying an automotive type oxygen sensor for use in an

A combustion control system includes a sensor assembly and a process controller, the sensor assembly including sensors for providing output signals indicative of process variables, the process controller responding to the output signals to maintain a desired operation of the process. The process controller continuously monitors parameters of the sensors and provides alarms whenever any of these parameters deviate from setpoint values, the process controller automatically prioritizing these alarms to provide a display of only the most relevant alarms. A housing enclosing the process controller provides EMI/RFI shielding of the process controller including the attenuation and absorption of the EMI/RFI energy.

Housing for a process controller

A combustion control system includes a sensor assembly and a process controller, the sensor assembly including sensors for providing output signals indicative of process variables, the process controller responding to the output signals to maintain a desired operation of the process. The process controller continuously monitors parameters of the sensors and provides alarms whenever any of these parameters deviate from setpoint values, the process controller automatically prioritizing these alarms to provide a display of only the most relevant alarms. A housing enclosing the processor controller provides RFI/EMI shielding of the process controller including the attenuation and absorption of the EMI/RFI energy.

Diagnostic system for combustion controller

An overcurrent protection system for AC motor control systems which provides a separate overcurrent shut down mechanism for each phase of the AC power used in an AC motor. These separate phase shutdown mechanisms provide protection for minor overcurrent conditions without shutting down the entire motor control system. The overcurrent protection system also provides a mechanical feedback apparatus for totally shutting down the motor control system only in a severe overcurrent condition.

Current fault detection system and method for AC controller

A method and apparatus of converting analog voltage signals to digital frequency signals comprises a voltage to frequency converter having an output which produces pulse trains that are proportional to the voltage level of an analog voltage signal applied to the converter. A microprocessor is connected to the converter for sampling the pulse trains during a fixed sampling period. The microprocessor detects the leading edges of the first and last pulse in the pulse train, stores the occurrence time for the two leading edges and then subtracts the occurrence times to calculate the duration time for all the pulses in the sample period between the leading edges of the first and last pulses. A counter counts the number of pulses between the first and last pulse, and a calculation is made dividing the number of pulses by the time duration to yield an accurate measurement of the frequency for the pulse train. A precision reference voltage along with a plurality of analog voltage signals to be measured, is applied to the plural inputs of a multiplexer. The output of the multiplexer is then amplified and a level shifted before it is applied to the converter. The microprocessor drives the multiplexer to sequentially apply signals to the converter. During each complete cycle of the multiplexer the microprocessor receives a pulse train corresponding to the reference voltage signal. A stored frequency for that reference pulse train is then compared to the actual frequency which results from the reference voltage to determine whether any shifts in ambient conditions have caused shifts in the output of the converter. This shift is interpreted as being caused by changes in ambient condition and is applied equally to all other measured frequencies. In this way, inexpensive components can be used while still maintaining accuracy for a wide range of ambient conditions.

Analog to digital conversion

An improved power supply for power switches arranged in a totem pole configuration is disclosed. A single power supply, having an output voltage substantially less than the voltage applied to the upper power switch, periodically charges a capacitor within a flying capacitor circuit. Microprocessor based control circuitry controls the charging and discharging of the capacitor and the periodic operation of the power switches resulting in the voltage at the output of the power switches being at system common or at the voltage applied to the upper power switch.

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Wickliffe, OH, United States of America

John J Fry