Abstract: A communications system with a local network having two metallic cables providing redundant channels between stations of a group with redundant optical rings forming a highway interconnecting those networks. An optical-electrical interface connects the networks and the ring.This interface includes an optical detector producing a corresponding electrical signal, an optical transmitter which repeats the detected message, and a control element connecting the output of the detector with the transmitter. A control signal supplied over one metallic line from the station which is transmitting to its interface causes the control element to disconnect the detector and transmitter to prevent operation of the combination as a repeater. The transmission is then supplied over another metallic line from the station to the transmitter and thence around the ring until it is converted to an electrical signal at the corresponding detector.

Abstract: There is provided a differential amplifier having a plurality of inputs connected through input resistors to a summing junction at the inverting input of a differential amplifier which also has a negative feedback path having a feedback resistor. One of the input resistors is connected to the output signal of the primary element or transducer. A second of the input resistors is connected to a zero compensating signal which varies with changes in the temperature of the transducer from a certain value at a reference temperature. A third input resistor is connected to a fixed signal of a value which is adjusted to correspond to the certain value of the compensating signal at the reference temperature but of opposite polarity so as to tend to cancel the compensating signal when the transducer is at the reference temperature. The combination of the three inputs then produces an output from the differential amplifier corrected for changes in the zero of the measurement due to temperature changes.

Abstract: A method for correlating in a digital data acquisition system the time sequence of a group of events at locations remote from the master station. The method corrects the time tags on the events record for the signal transmission time between the master and remote stations and also takes into account the turnaround time at the remote station. In addition, compensation is made for the drift of the remote clocks with reference to the master clock.

Abstract: A thin film resistance thermometer is manufactured to have a predetermined temperature coefficient of resistance while minimizing the amount of metal in the film. The process involves the production of a metal film deposit on an insulating substrate such that the film deposited has a bulk coefficient substantially higher than the desired coefficient with the film being deposited to a thickness that produces the desired coefficient.

Abstract: A refractory protection tube for immersion molten metal parameter determining devices having a thin perforated metal tube with a coating of refractory fibers and a binder to provide thermal insulation, freedom from out-gassing and mechanical strength.

Abstract: Apparatus for compensating for the IR drop in a polarographic type electrochemical cell which utilizes an injected current for in situ calibration includes means operable for a brief period of the current injection to change the cell bias so as to maintain the total cell current for that period at the value existing prior to current injection as well as means for maintaining throughout the remainder of the injection period the cell bias which exists at the end of the brief period.

Abstract: A method for in situ recalibration of a polarographic type electrochemical measuring system having a fourth electrode which includes adjusting the sensitivity of the system so that the measured value of a standard sample is correct and then measuring the transient response of the cell under those known sample conditions. A measurement of the transient response is then made for recalibration under unknown sample conditions with a readjustment of the sensitivity of the system in accordance with the change in the value of the transient response.

Abstract: There is provided a multirange, variable capacitance pressure transducer by bonding a diaphragm plate that is conductive between a pair of insulating plates with the diaphragm plate having a plurality of cavities provided on each side so that diaphragm deflection areas of different sizes are defined. The surfaces of the pair of plates in the cavities are covered by a conductive coating so that the coatings form capacitors with the deflection areas. A fluid communication path is provided to each cavity so that the pressure difference to be measured is placed across the deflection area. Electrical connection is made to selective combinations of said capacitors to provide pressure transducers for a number of ranges in one unit.

Abstract: A control system is provided for controlling the distribution of load among a plurality of generators when some of those generators respond quickly to control and some do not. The area control error signal is divided into portions to provide a unit error signal assigned to each generator. A control is utilized which responds to the unit error signal to reposition the governor motor until the error signal is reduced to zero. Applying that control to slow responding units requires anticipation of the generation changes to be expected after full response. Control from the unit error signal is modified in accordance with the difference between the desired generation for the units as required for economic considerations and the actual generation with that difference being modified by a signal which is a function of the actual generation. That function is expressable by the Laplace transform ##EQU1## .

Abstract: A humidity sensing element of the capacitance sensing type having two sets of interdigitated fingers of thin film platinum deposited on a glass substrate, all covered by a coating of water absorbing material such as cellulose acetate butyrate or a silicone rubber. The coating is of thickness such that it is substantially equal to or greater than the period of the fingers of the interdigitated electrodes.

Abstract: A capacitive pressure transducer utilizing a plate of electrically conductive semi-conductor material sandwiched between a pair of plates of inorganic electrically insulating material and electrostatically bonded thereto. A pair of concentric circular recesses are etched in the plates in such a way as to form cavities on opposing sides of the conductive plate and to define a diaphragm area on that plate. Apertures are drilled through the insulating plates to expose the cavities to the pressures to be measured. The surfaces of the insulating plates in the cavities have deposited on them electrically conductive surfaces which form capacitors with the diaphragm area on the conductive plate. A stress relief area is provided on the high pressure side surrounding the diaphragm area. In that stress relief area, the conductive plate is unrestrained by the adjacent insulating plate.

Abstract: A method for modifying an area control error signal for controlling the generation in each area of a multiple-area interconnected electric power system using net-interchange tie-line bias control where the area control error is calculated in accordance with the equationACE=.DELTA.P.sub.t1 -10B.times..DELTA.fwhere .DELTA.P.sub.t1 is the deviation of the measured net interchange from its scheduled value, .DELTA.f is the deviation of a system frequency from its set value, and B is the frequency bias of the area. The modification involves the integration of .DELTA.P.sub.t1 to produce a signal representing a measured value of the inadvertent interchange II'.sub.t1, and integration of .DELTA.f to produce a signal representing the time deviation TD'. The time deviation is multiplied by the value 10Bf.sub.o /3600 times 1/T where B is the area frequency bias and 1/T is the control weighting factor. The product of the multiplication is subtracted from the signal II'.sub.

Abstract: A bus structure for the interconnection between a data bus capable of transferring a plurality of words and a local bus which can carry only one word. This structure includes latches for storing the plurality of words for simultaneous transfer over the data bus or for sequential transfer over the local bus as required. Control logic operates to perform the necessary control over this interconnection to effect the required operation.

Abstract: An analog voltage to duty cycle converter is provided using a series connected resistor and capacitor. The capacitor is charged in one direction through the resistor from the difference between the analog voltage and a reference voltage maintained across a zener diode by one polarity of output from a differential amplifier responding to the charge across the capacitor. When the charge across the capacitor reaches the difference necessary to cause the differential amplifier to change the polarity of its output, a positive feedback firmly toggles the output to the other polarity and the capacitor is allowed to charge in the opposite direction due to cut-off of the zener current by a diode in the amplifier output circuit. The capacitor then charges in an opposite direction due to the analog voltage alone and the reference voltage again switches "on" when the amplifier output goes positive. The duty cycle is then proportional to the analog voltage.

Abstract: A plurality of recesses and interconnecting paths are etched into the surface of a silicon wafer. A plate of borosilicate glass carrying thin-film metal deposits in a corresponding pattern is electrostatically bonded to the silicon to form a multiple-cavity variable capacitance pressure transducer.

Abstract: A preamplifier for use primarily with a solid state line scanner for amplifying the signal output from the scanner and suppressing the noise from switching spikes featuring a cascode-connected input stage in a preamplifier having its gain stabilized by negative feedback.

Abstract: An optical transducer (10) having a plurality of concentric cores (15,17). An intermediate cladding (16) is disposed between the inner and outer cores and an outer cladding (18) surrounds the outer core to define a symmetrical cylindrical transducer structure. Light propagated through the inner core (15) from a source (19) is coupled into the outer core (17) as a result of penetration of the evanescent electric field from the light in the inner core through the inner cladding (16) to the outer core. Control of the coupling length may be effected by suitable selection of the transducer structure parameters. At least one of the portions of the transducer is formed of an acousto-optically variable material whereby an acoustic field acting on the transducer causes a modulation of the coupled light so as to provide in the outer core (17) a modulated light signal suitable for detection by a receiver (21). Localized control of the parameters of the transducer may be effected to provide focusing of the coupled light.

Abstract: A molded housing contains a pair of cooperating contacts arranged to be magnetically blown open and an arc chute therefor. The contacts are biased closed and there is no mechanism for manually operating or latching open the contacts. The magnetically blown-open contacts are connected in series with respective poles of a conventional circuit interrupter which also has magnetically blown open contacts but which also has manual operating means and latch means for the contact system.

Abstract: An electrical power generating system includes a prime mover having a throttle control for converting a source of input energy into a mechanical output. The system includes an electrical generator having a plurality of output windings and a field winding for exciting the output windings. The generator is mechanically coupled to the mechanical output of the prime mover. Means are provided for sensing a plurality of parameters related to the performance of the system and further means are provided for converting each of the sensed parameters into a digital signal indicative of the magnitude of the sensed parameter. Additional means are provided responsive to the digital signals for developing a plurality of electrical output signals. The electrical output signals are utilized to control either or both the generator and the prime mover to thereby control the output of the power generating system.

Abstract: A solid state trip circuit is disclosed which uses a shunt path saturable transformer comprised of a current transformer having a relatively high resistance shunt which serves to apply input voltage to the transformer primary winding. The larger the input current the higher the voltage drop across the shunt and the more quickly the transformer iron will become saturated. The saturation time during each half cycle then produces a measure of the current flow in the primary line. The output of the secondary winding of the transformer as well as a direct but resistive connection from the input circuit lines are applied to a solid state trip circuit which operates a circuit breaker trip latch. Energy for tripping at lower overload current is derived directly from the applied voltage from the line. At high overload conditions however, direct tripping occurs through energy derived from the transformer rather than directly from the line voltage.