Abstract: A resistance wire sensing overcurrent protection module (CSM) for an electrical supply circuit (SC) having a hot temperature sensing diode (32) mounted at the center portion (8c) of an M-shaped resistance wire (8) connected in the supply circuit and an ambient temperature sensing diode (20) mounted on a substrate (18) supported between the supply terminals (4a-b, 6a-b), both diodes being connected to respective pairs of terminals (12a-b, 10a-b) mounted on a header (18) along with the supply terminals. A cover (46) is mounted on the header and filled with glass micro-balloons (48) to isolate thermally the two diodes. A constant current circuit (49) supplies constant current to the two diodes which operate a differential amplifier (52) having an output proportional to the temperature difference as a measure of supply current. This output trips a Schmitt trigger comparator (54) when the supply current rises to an overload value.

Abstract: An RTD bridge is coupled with a microprocessor-based data acquisition system for linear reading of temperature and for accuracy at the level of the precision data acquisition system. A reference divider is paralleled with the RTD bridge between a voltage reference source and ground, and linearization is effected in accordance with a function which is a geometric progression of the measured non-linear count. Calibration is effected in one embodiment with a precision divider, or with the bridge itself by making readings at the lowest and at the highest temperature intended with the bridge, according to another embodiment of the invention.

Abstract: A test board is provided for resistance testing of dynamoelectric machines, and in particular of the windings of an electric motor, in which a standard resistance value is adjusted automatically for changes in ambient temperature. In the preferred embodiment, the standard value is an input to an electrical comparator. A temperature sensor is positioned to sense ambient temperature and the input from that sensor is used to adjust automatically the standard resistance value for the motor under test. The temperature compensated resistance value also is used to determine a range of values about the standard resistant value at the ambient temperature. The resistance of the motor winding then is obtained and compared with the resistance standard. After comparison, an indication is given to the operator of the device, to show a pass or fail condition.

Abstract: A microwave oven includes a gas sensor for detecting a cooking condition. The resistance value of the gas sensor varies in response to the concentration of the gas generated from the foodstuff being cooked in the microwave oven. A resistance-to-frequency converter including an astable multivibrator is provided for converting the variation of the resistance value of the gas sensor into a frequency signal. A cooking constant setting circuit is provided for developing a signal of a reference frequency in response to a menu to be conducted. The frequency signal, indicative of the resistance value of the gas sensor, obtained by the resistance-to-frequency converter is compared with the reference frequency to terminate the cooking operation when the frequency signal reaches the reference frequency.

Abstract: A strain measuring device using a Wheatstone bridge circuit. An excitation voltage changing switch switches from one excitation voltage to a different excitation voltage in accordance with a controlling circuit providing sequence operation of them and of other circuit elements to remove spurious components affecting the measurement of strain. Such spurious components include potential errors due to thermal electromotive force produced inside or outside said Wheatstone bridge circuit and sensitivity error due to drift voltage occurring in the driver circuit of the bridge current source. A comparator may be used to effect judgment of the amount of the measured value of the voltmeter, so that the controlling circuit causes excitation voltage changing switch to select only two excitation voltages out of at least three for switching no matter how many excitation voltages are provided for in the bridge current supply source.

Abstract: A thermocouple linearizer circuit for use in a device for digitally displaying the temperature of a thermocouple. The circuit includes a plurality of proportional correction means, each connected to receive a non-linear electrical signal representing the temperature of a thermocouple. The correction circuits generate a correction signal proportional to the difference between a non-linear electrical signal and a predetermined reference signal. The correction signals are initiated when the non-linear signal exceeds the respective reference signal in each correction circuit. An arithmetic unit is included for adding the correction signals and the non-linear signal thereby forming a signal corresponding to a linear function of the temperature of the thermocouple.

Abstract: In an apparatus comprising a high-voltage measuring capacitor and, in particular, comprising a high-voltage measuring capacitor formed by a high-voltage conductor of a fully insulated, metal-encapsulated high-voltage switch-gear installation and by a surface electrode associated with the former, an auxiliary capacitor is associated with and located adjacent to said high-voltage capacitor. The auxiliary capacitor is part of an evaluation device which generates a signal corresponding to capacitance changes of the auxiliary capacitor resulting from external influences. Following the evaluation device is an indicating device for signaling the occurrence of such capacitance changes and/or a control or regulating device for compensating for capacitance changes of the high-voltage measuring capacitor caused by the same external influences.

Abstract: The coupler inserts in an RF transmission line and produces a pair of DC signals whose level is representative of the magnitude of forward or reverse power flow therethrough.Power flow is sensed via a pair of non resonant loops, each of which is terminated and oriented such that AC signals, whose amplitudes correspond to the forward or reverse power flow magnitude, are produced. Since the RF signals produced by the loops are dependent on the RF power flow frequency, unique circuitry processes the RF signals and compensates for this frequency dependence whereby the processed AC signals are substantially frequency independent.Also disclosed are improved rectification circuitry, and a means to compensate the coupler against error due to thermal drift of coupler components.

Abstract: A measuring arrangement for measuring the effective value of an a.c. signal. Said a.c. signal is applied to a first thermal convertor, while a d.c. output signal is applied to a second thermal convertor. The two thermal convertors differentially drive a differential amplifier, which at its outputs delivers the d.c. output signal. For values of the d.c. output signal which are smaller than a threshold value, a negative feedback signal which linearly depends on said d.c. output signal is applied via an additional negative-feedback network to at least one of the inputs of the differential amplifier. This facilitates zero-point adjustment, and also allows the measuring speed to be increased.

Abstract: Apparatus which provides a digital signal which represents the unbalance in a resistance bridge. The apparatus includes a source of direct-current voltage which is applied alternately and repetitively with opposite polarity to input terminals of the bridge. An amplifier is connected to the bridge output terminals. Analog-to-digital converters are connected to the output of the amplifier in such a way that one converter is connected to the amplifier output at a time when a positive voltage is applied to the bridge input and another converter is applied to the amplifier output at the time that a negative voltage is applied to the bridge input. A count is provided which represents the difference in the digital signals provided by the two converters. Such output is unaffected by any initial unbalance in the amplifier and is also not responsive to thermo-electrically generated electromotive forces.

Abstract: A compensating circuit for a cold junction of a thermocouple includes a sign inverting amplifier, a power source and a summing amplifier. A thermo-electromotive force of the thermocouple, the output of the sign inverting amplifier and the voltage of the power source are applied to one input terminal of the summing amplifier through resistors. An output corresponding to the temperature of the hot junction of the thermocouple is obtained from the output terminal of the summing amplifier.

Abstract: Physical quantities, such as temperature, mechanical stress, gas concentration and acidity, can be measured by means of elements which generate an EMF as a function of the relevant quantity. In many cases the temperature dependence of the conversion is inconvenient. The proposed temperature correcting circuit considerably reduces the said temperature influence, at least for a given operating range, in that the temperature-dependent internal resistance of the element is measured or used by means of an alternating current and the EMF is corrected by means of this temperature information.

Abstract: The combined current and voltage measuring apparatus has a cast resin body which supports the current measuring unit. The voltage measuring unit includes a capacitive voltage divider with an amplifier connected thereto. The cast resin body is also utilized as dielectric for the capacitor on the high-voltage side of the capacitive voltage divider. Embedded in the cast resin body is an auxiliary capacitor with a dielectric which, with respect to temperature dependence, corresponds to the dielectric of the high-voltage capacitor. The auxiliary capacitor, in series with a resistor, is connected to an auxiliary generator. The voltage dropped across the resistor is supplied, after rectification, to an input of a differential amplifier; the other input of the differential amplifier is connected to the terminal away from ground of the capacitor on the low-voltage side of the capacitive voltage divider.