Abstract: A measuring instrument has first and second memories for storing measured data. A display displays the measured data stored in the first memory. When a new measured data is obtained in the measuring instrument, the measured data is written in the first memory. The old data measured prior to the new measured data is transferred from the first memory to the second memory before the new measured data is written in the first memory. When a data restore command is given, a data relocation is carried out between the first and the second memories.

Abstract: An inductive load energized by a variable duty cycle pulse signal contains ripple at steady state conditions, and the average current is used as feedback to a controller. The average current is obtained without filtering by synchronously sampling the local maxima and minima of the current and averaging the last two samples. The maxima and minima are detected by sampling at the falling and rising edges of the pulse signal. The method is implemented by software in a microprocessor or by hardware comprising a pulse generator, sample and hold circuits, and an averager. The resulting average value is then asynchronously sampled by a microprocessor.

Abstract: A "component test" function is provided in a low-power, portable test instrument like a digital multimeter. A test stimulus waveform is synthesized digitally, and a digital trigger signal from the synthesizing circuitry is used to trigger acquisition of measurement data. A single-channel front end acquires voltage scan data over one cycle of the test stimulus waveform following the trigger point. Current scan data is later acquired through the same acquisition circuitry beginning at the same trigger point relative to the start of a later cycle of the stimulus waveform, so that the voltage and current scan data, although acquired separately, are very closely synchronized relative to the stimulus waveform, as a result of which they maintain their phase relationship. Stored voltage and current scan data are aligned accordingly and concurrently displayed so as to form a Lissajous pattern on a small display.

Abstract: A method and a device, after a fault has occurred in a power network, for measuring and recreating the phase currents I.sub.B prior to the occurrence of the fault by determining continuously, starting from sampled measured values of the phase currents up to the time of the fault for each phase, the amplitude I and the phase angle .phi. of the phase currents based on two consecutive sampled measured values, whereupon a comparison is made between the last determined value I.sub.k obtained and the rated current I.sub.n of the power network. If I.sub.k is greater than I.sub.n, it is considered that a fault has occurred and the phase currents prior to the fault are indicated as I.sub.B =I.sub.k-1 .multidot.sin (.phi..sub.k-1 +.omega.(t-t.sub.k-1)).

Abstract: In a watt-hour meter in which first and second input signals representing an analog electric current and an analog voltage of an alternating current are converted into first and second digital signals, a first adder produces a sum signal which represents a sum of the first input signal and an additional analog signal of a frequency different from that of the first input signal and which is substituted for the first input signal. The meter may further comprise a second adder which adds another additional analog signal to the second input signal. Alternatively, the meter comprises low-pass filters and oversample-and-convert circuits to produce the first and the second input digital signals.

Abstract: A ground-free device for measurement of electrostatic potentials on objects. The device is based on the fundamental concept that the static charge on most objects can be estimated by means of a discharge terminal equipped with a capacitor.

Abstract: An AC input signal is sampled with a plurality of sets of equally spaced samples, but whose sample interval between the samples does not exactly divide the period of the input signal. Nevertheless, and error cancellation technique allows ultra accurate measurements to be made. The samples in each set of the plurality of sets are supplied to a computational process that extracts some parameter; e.g., RMS voltage. The extracted parameter is in error, owing to the non aliquot nature of the sampling. The size of the error is related to, among other things, where on the input waveform the associated set began. The error is a period AC function of that starting location. By arranging for n-many sets to start at phase differences of 1/n apart on the input waveform, a series of n-many parameter.sub.i are obtained that are each of the form [result.sub.i +error.sub.i ]. Thus, the error.sub.i are sampled at aliquot locations along an error function, and therefore sum to zero. Thus, averaging the parameter.sub.

Abstract: A pulse detector keeps track of the peak value of an analog input signal and clocks output data pulses into a flipflop and shift register at peak values thereof while it monotonically increases in magnitude for each polarity. The data input to the flipflop becomes logic zero once the analog input signal changes direction toward the opposite polarity, whereby the last output data pulse in the shift register corresponds to the maximum peak of the analog input signal during the given polarity.

Abstract: A procedure and apparatus for the measurement of the currents in a frequency converter, provides that the phase currents of the frequency converter are measured by storing, in memory, signals corresponding to the current of the d.c. circuit of the converter and by producing a current value corresponding to the phase current from the previous and the momentary signals.

Abstract: A measurement circuit for measuring the level of an input electrical signal, the circuit comprising an input amplifier biased from a bias voltage, receiving the input signal, and producing an output signal, followed by a detector module itself followed by an integrator delivering an integration signal, these three components constituting a measurement channel, the integration signal being the sum of an offset signal and of a level signal which is proportional to the level of the input signal.

Abstract: A current-to-frequency converter 12' (FIG. 3) for use with an accelerometer 10 comprises a storage capacitor 13 which receives the accelerometer current and develops a charging voltage, reset charging means 25 which delivers timed charges to offset the voltage by predetermined amount and voltage sensing means 14' which senses the charging voltage reaching positive or negative thresholds in order to initiate a reset and offsetting the voltage. The polarity of charging voltage at which reset is triggered determines that polarity threshold as being half the magnitude of the offset voltage but the opposite polarity threshold of greater magnitude so that the voltage on the reset capacitor avoids it.

Abstract: A method of and an apparatus for measuring small electrical signals with a computer-supported error-compensating measuring circuit (10) which includes a multiplexer (13), a following amplifier (15), an analog-to-digital converter (16) and a calculation device (17). The multiplexer has at least one pair of measuring signal input terminals (n-1, n) and one pair of zero volt input terminals (A, B) and connects them repeatedly to the following amplifier (15) for signal recording. Memories for digitized signals are present in order to correct, by means of the calculation device, actual measuring signals with correction values determined from a set of first measured signals so that a precise indication value is produced independent of offset errors and their variation.

Abstract: In a watt-hour meter in which first and second input signals representing an analog electric current and an analog voltage of an alternating current are converted into first and second digital signals, a first adder produces a sum signal which represents a sum of the first input signal and an additional analog signal of a frequency different from that of the first input signal and which is substituted for the first input signal. The meter may further comprise a second adder which adds another additional analog signal to the second input signal. Alternatively, the meter comprises low-pass filters and oversample-and-convert circuits to produce the first and the second input digital signals. As a further alternative, the meter comprises a first inverter for inverting a selected one of the first and the second input signals into a first inverted signal.

Abstract: A circuit for measuring the tension of an electricity line, the circuit comprising a capacitive divider comprising first and second capacitors, first and second amplification lines for amplifying the tension across the terminals of the second capacitor, said amplification lines having respective time constants of the order of 100 ms and in the range 2.5 ms to 15 ms, the amplification lines being connected to respective first and second controlled switches under the control of a logic circuit, the circuit further including a circuit for generating the absolute value of the algebraic difference between the signals provided by the amplification lines, and a comparator circuit for providing an output signal that controls the logic circuit causing it to change state when said absolute value exceeds a given threshold.

Abstract: DC offset is measured by separating the positive and negative half cycles of the AC waveform, obtaining a measure of the energy content of each type of half cycle and subtracting one from the other and accumulating the result. The accumulated result is measured against a threshold which is selected to have a known relationship to the units used to measure the DC offset. Each time the threshold is exceeded, this increments a counter and at the same time resets the accumulator. The contents of the counter can then be multiplied by an appropriate scaling factor. The square root of this result gives a measure of DC offset.

Abstract: In a watt-hour meter in which first and second input signals representing an analog electric current and an analog voltage of an alternating current are converted into first and second digital signals, a first adder produces a sum signal which represents a sum of the first input signal and an additional analog signal of a frequency different from that of the first input signal and which is substituted for the first input signal. The meter may further comprise a second adder which adds another additional analog signal to the second input signal. Alternatively, the meter comprises low-pass filters and oversample-and-convert circuits to produce the first and the second input digital signals. As a further alternative, the meter comprises a first inverter for inverting a selected one of the first and the second input signals into a first inverted signal.

Abstract: A method of detecting amplitude value of AC electric quantity in electric power system, where five sampling values obtained in sampling performed in sequence at a period of 1/4 of the period of the rated frequency of the AC electric quantity are used, and the first through fifth sampling values are squared respectively and the squared values of the second and fourth sampling values are multiplied by four and the squared value of the third sampling value is multiplied by six and the sum total of these values is obtained, and then the sum total is divided by eight and its square root is estimated, thereby the amplitude value of the AC electric quantity is obtained. Even if the frequency of the AC electric quantity to be detected is varied about .+-.5%, its amplitude value can be operated with good accuracy and the operation result can be obtained at high speed.

Abstract: A high voltage measuring circuit for broadband measurement of transient signals occurring in high voltage apparatus. The measuring circuit is housed in a shielded housing having an input sensing circuit for connection to a capacitive grounded tap of the high voltage apparatus. The sensing circuit is connected to an output circuit through an electrical shielded connection. The measuring circuit generates output signals which are replicas of the transient signals appearing on the bushing of the high voltage apparatus. The broadband of the measuring circuit extends over a frequency range of from about 1 Hz to 1 MHz and has a signal level higher than background noise.

Abstract: An electronic watt-hour meter includes a multiplier/integrator circuit which performs "pulse height-pulse width" multiplication of current and voltage and simultaneously integrates the product of this multiplication to generate packets of electrical charge representative of the electrical energy consumed. A first set of switches alternately, at one-half the frequency of a pulse width modulated (PWM) signal having a duty cycle proportional to the current, connects one of a pair of capacitors to be charged by the voltage signal, and the other capacitor to dump charge into an accumulator. When charge in the accumulator reaches a preset value, a pulse is generated representing a predetermined unit of energy. When the first capacitor is connected to the voltage signal by the first set of switches, a second set of switches applies the voltage to the first capacitor in one sense when the PWM signal has one value and in the opposite sense when the PWM signal has a second value.

Abstract: A voltage monitoring device is adapted to fit within or be mounted externally of the housing of a standard electricity meter. The device repeatedly monitors the voltage of the mains supply, stores data derived from the measurements for consecutive predetermined periods, and releases the stored data upon request.

Abstract: A method for measuring the difference between two voltages with a time-controlled measuring cycle includes feeding two voltages with opposite polarity to one integrator, initially integrating up one of the voltages and subsequently integrating down the other of the voltages with the integrator in an integration cycle, and delivering a voltage corresponding to the mean valve of the difference between the voltage at an output at the conclusion of the integration cycle.

Abstract: An electronic circuit arrangement for producing an output signal representative of the average value of an alternating voltage in a power transmission system, composed of: at least one circuit unit composed of a pulse width modulator (6) connected to derive, from the alternating voltage, a train of pulses modulated in width as a function of the amplitude of the alternating voltage and with a defined phase relation to the alternating voltage, an electronic circuit (4,8) connected to derive, from the alternating voltage, an alternating signal which varies in frequency with the alternating voltage and which has the defined phase relation to the alternating voltage, and a signal multiplying device (14) connected to receive the train of pulses modulated in width and the alternating signal for multiplying the pulses and the alternating signal to produce a product signal having an amplitude proportional to the average magnitude of the alternating voltage; and a signal to frequency converter (16) connected to derive

Abstract: A multimeter comprising a clip-on device (12) and a Hall-effect measuring circuit (5) for measuring either a direct or an alternating current I. Moreover, the multimeter comprises a voltage-measuring circuit (2) for measuring either a d.c. or an a.c. voltage U as applied to two input/output combination sockets (3, 4). By means of a function transformer (30), a digitizing unit (19), a digital unit (25) and further circuit components which also include a battery-operated power-supply unit (1), the measured current and/or voltage values, by taking into due consideration any stored correcting values as well as such correcting values which result from adjusting measurements, and any circuit-specific constants as already previously stored by the manufacturer, are processed in accordance with predetermined rules for proportioning into display signal-waveform-independent values relating to the current I, the voltage U, the apparent power Ps, the real power Pw, the power factor, the frequency f, and further values.

Abstract: A telephone network test apparatus for testing for a number of different conditions that can cause harm to a telephone network. Described herein is a circuit for measuring signal power level as well as a circuit for measuring surge voltages. Finally there is described a circuit for measurement of voltage balance.

Abstract: A method of using a waveform to sound pattern converter that produces an audible image of a time dependent signal by digitizing the signal to produce a plurality of discrete level signals, and produces a different audible tone signal for each level of the discrete level signals. A speaker is provided for producing audible sounds and circuitry is provided for driving the speaker to produce an audibly perceptible reference frame indicative of a predetermined time duration and also for driving the speaker with the audible tone signals such that the audible tone signals have the same time orientation with respect to each other as the discrete level signals have in the time dependent signal. The sounds are provided to listener to enable the listener to distinguish the shape of the time dependent signal based on the position and time relation of the tone signals relative to the reference time frame signal.

Abstract: A transformerless, self-contained, low cost, small size, light weight solid state electronic watthour meter is described which employs thin film ferromagnetic current sensors of the type which are magnetically coupled to power conductors whose current flow is to be sensed and metered and which provides electrical isolation between the power conductors and the sensing and metering circuitry. The meter is self-contained in that it draws its operating direct current supply potential required to operate the meter directly from the power conductors being metered and does not require a separate battery or transformer coupled direct current power source. The entire meter circuitry, including the thin film ferromagnetic current sensors which can be fabricated by thin film technology and the direct current power supply and the watthour meter circuitry, all are susceptible of fabrication on a single substrate using semiconductor integrated circuit fabrication techniques.

Abstract: A system for transmitting traces of an oscilloscope (16) to a remote locan. A transmitter circuit (18) digitizes and transmits the traces to the remote location. A receiver circuit (24) at the remote location receives the transmitted signals and delivers these signals to a destination oscilloscope (26). At the transmitting location, the vertical output signal of the oscilloscope is amplified and fed to an analog-to-digital converter. The digitized output signal of the converter and the oscilloscope's timebase gate signal are stored in a memory circuit and subsequently transmitted to the remote location via a first modem (20). At the remote location, the receiver circuit (24) comprises a universal asynchronous receiver transmitter (UART) interfacing with a second modem (22), a memory circuit for storing the transmitted signals, and associated circuitry for restoring the oscilloscope signal's amplitude.

Abstract: A digital instrument is represented by an analog-to-digital converter 17 controlled by a CPU 10 to effect measurements at regular intervals. The digital measurements are stored in a history file in a RAM 14, e.g. the most recent 100 or 500 measurements. The measurements are also linearly processed by rounding and range scaling to produce 100 reduced measurements in a second file in the RAM 14. This file is cyclically read out to a digital-to-analog converter 18 to produce a voltage on a terminal 22 for application to an oscilloscope which provides a display from which features of the measurements (e.g. a trend or a periodic component) can be seen. In order to allow for flyback and reset the 100 reduced measurements are held in a file of larger capacity (e.g. 130 or 150 measurements) which is cyclically read out. As the oldest of the 100 measurements is read a driver 19 provides a trigger pulse on a terminal 23 for the oscilloscope external trigger input.

Abstract: A welding current measuring apparatus for a resistance welding machine comprises a current detector for use in measuring and detecting welding current flowing through the resistance welding machine, a memory for successively storing and holding the current values detected over the whole energizing time, and a device for specifying a desired energizing cycle interval to compute and display current values after completion of welding, wherein any energizing cycle interval is specified at will after completion of welding so that the current values or the current waveform in the specified interval can be displayed.

Abstract: A switched-capacitor integrator is employed in an electronic watthour measurement device for integrating the average component of a product signal formed by pulse-width modulating an analog signal proportional to one of a load current and voltage at a pulse duty ratio proportional to the other of the load current and voltage. A hysteresis comparator forces the direction of integration to alternate between positive and negative limits for balancing out offset voltages in the integrator and comparator. A triangular-wave generator employed as part of the pulse-width-modulation technique is also implemented using a switched-capacitor integrator. The switched-capacitor integrators permit fabrication of the circuit with the required accuracy without needing external, discrete time-constant-determining resistances and capacitances. Measurement accuracy is determined by the ratio of capacitances of two on-chip capacitors, the accuracy to a clock signal and two reference voltages.

Abstract: A measuring circuit for obtaining a mean square value of a power distribution line paramter and a process for obtaining a mean square value is disclosed. The measuring circuit and process exploit my discovery that an accurate measurement of the mean square may be closely approximated by sampling the power parameter an odd number of times greater than one during the power parameter cycle. When the power parameter is sampled an odd number of times (N) during its cycle aliasing errors due to the existence of odd harmonics above the Nyquist Frequency are minimized. As a result, the means of the most recent N sample values squared is very nearly equal to the true mean square value which would be produced by a continuous integration of the square of the power parameter during its period divided by the period. By sampling at a relatively low frequency, errors and circuit complexity are reduced, and the speed with which an acceptable mean square value is obtained is increased.

Abstract: An impulse measurement system for displaying impulses in an alternating current electromagnetic energy waveform, the impulses generally occurring at frequencies substantially greater than that for the waveform. The system comprises high speed sample memory for recording the high frequency impulses, memory for recording the waveform, and display for receiving the high frequency impulses and the waveform from the high speed memory and the waveform memory, respectively, and displaying both the high frequency impulses and the waveform simultaneously, thereby permitting efficacious identification of the cause of the impulses.

Abstract: A precision current meter of wide dynamic range and sensitivity to low currents is disclosed. The precision current meter is particularly useful as a component for spectrochemical computations in spectrometers for the simultaneous multielement analysis of unknown samples in solution. The precision current meter comprises a source of input current, preferably a photomultiplier tube, an integrator having an integrating capacity for detecting the input current from the source, a source of reference currents including an offset current, a switch with a drain current coupled to the integrator. A clock is provided for generating clock signals for the current meter, including a series of pulses to actuate the switch and thereby to admit drain current segments to the integrator.

Abstract: This invention relates to a waveform observation apparatus such as an oscilloscope, and more particularly to a waveform observation apparatus suitable for a liquid crystal oscilloscope having a liquid crystal display of low power consumption.The waveform observation apparatus comprises at least a waveform memory in which a waveform data is to be written, an input circuit to control the waveform memory to write the waveform data therein and a power supply circuit to drive the waveform memory and the input circuit. The power supply circuit includes means to only intermittently apply the power supply voltage for at least part of the input circuit for a time necessary for writing a waveform. This causes the power consumption to be lowered.

Abstract: The digital test probe has an electrically conductive probe needle for making electrical contact with different test locations of a digital circuit. A logic level detector connected to the needle provides a data signal having a logic level representative of that at the test location. N indicators, such as light emitting diodes, are provided with each presenting an indication of the logic level at an associated one of N test location. A memory has N storage locations and each stores a binary level signal representative of the logic level at an associated one of N test locations. Each time the operator actuates a switch, data representing the logic level at that test location is written into an associated location in the memory. In this way, the operator need not divert his attention from the probing of test locations to look at the indicators while testing the various locations since the indicators will provide him with a visual readout after he has finished.

Abstract: The system includes a basic recorder module where a delay element is followed by a solid state buffer memory, digital interface circuits for transferring the recorded data, processing means, a printer and/or magnetic memory unit, a detachable programming terminal for the dialogue with the recorder and its programming, as well as a separate power supply for the working part, so that the latter is only supplied in the recording mode or during a connection of the programming terminal.

Abstract: An integrating circuit for generating control signals representing watt-hour consumption for connection to an electronic watt-hour meter. The circuit includes a Hall effect sensor for sensing watt-hour consumption, a circuit for integrating the sensed watt-hour consumption, and a circuit for compensating for DC offset voltage generated by the Hall effect sensor.

Abstract: Digital measuring device, including a trigger generator having an input for receiving an analog measuring input signal, a variable delay line being connected to the trigger generator and having an output, an analog/digital converter receiving the analog measuring input signal, a transient memory connected to the analog/digital converter, a picture refresh memory connected to the transient memory for storing the measuring input signal, a Walsh function generator connected to the picture refresh memory, a liquid-crystal picture screen being connected to and addressed by the Walsh function generator, the output of the variable delay line being connected to the analog/digital converter, the transient memory and the picture refresh memory, and a selectable time base being connected to the variable delay line, the analog/digital converter and the transient memory.

Abstract: An electronic wattmeter in the form of an electronic watt-transducer circuit requiring a minimum number of components that can be fabricated by monolithic semiconductor integrated circuit manufacturing techniques and which provides a direct current output signal that is proportional to watts. The electronic watt transducer circuit comprises a first transformer for developing a first voltage related signal proportional to the input voltage to be measured and a second current transformer for developing a second current related signal proportional to the input current to be measured. A pulse width modulator is connected to receive the first voltage related signal and an input repetitive sampling signal for producing repetitive pulse width modulated output pulses having instantaneous pulse width proportional to the corresponding instantaneous amplitude of the first voltage related signal.

Abstract: An electronic wattmeter monitors the current and voltage of power lines and generates unitized voltage pulses at a frequency that is proportional to the average power carried by the lines. The wattmeter includes a current transducer that is inductively coupled to the monitored power lines. The transducer generates an induced current that is representative of the current that flows in the lines. The current transducer includes a magnetically permeable frame which has two magnetically permeable, spaced parallel leg members and a magnetically permeable cross-member that is detachably affixed between the leg members. The monitored power lines pass through an aperture defined by the leg members and cross-member of the frame and the frame additively applies the magnetic fields of the conductors to a coil that is inductively coupled to the frame. The coil generates an induced current corresponding to the current of the conductors.

Abstract: The voltage divider comprises a capacitor column (11) for dropping nearly all of the high voltage and a base capacitance (10) connected in series therewith so that a small voltage appears there across. Said discharge circuit comprises a diode rectifier bridge (15, 16, 17, 18) connected by its AC terminals in parallel with the base capacitance, and two identical windings (20, 21, 22, 23) connected in parallel respectively with two of the diodes (15, 16) of the bridge, both of said winding-shunted diodes being connected to the same one of the AC terminals of the diode bridge.

Abstract: A dual-slope integrator is provided in the usual manner with input switches for a measured voltage and reference voltage and with a first counter having a count capacitor N.sub.1, in addition to the usual integrating resistor and integrator condenser in circuit with an integrating amplifier. The output of the latter is applied to a comparator and a clock-pulse generator produces the counting pulses. According to the invention, a second counter is provided with a capacitor N.sub.2 so that the two counters together have a capacity N.sub.1 .times.N.sub.2, the input switching circuit is keyed by the clock pulses, and a further amplifier of amplification N*.sub.2 is provided, the amplification factor N*.sub.2 being approximately equal to N.sub.2.

Abstract: A measuring circuit for integrating electrical signals. The measuring circuit comprises a delay line which is connected between the output of an integration stage and the input of a discharge stage in order to render the value of the discharge current dependent on a voltage which remains during said discharging. The circuit may also comprise a timing circuit which ensures that said constant voltage is maintained for a sufficiently long period of time. The measuring circuit may also comprise a circuit for advancing the opening a discharge switch in order to take into account the time required for transmitting the control signals for opening the discharge switch to this switch.

Abstract: An incoming a-c signal, whose amplitude is to be measured, successively passes through several decadic attenuator stages settable by respective cascaded decadic stages of a reversible counter. The attenuated signal is rectified and its voltage, or the RMS value thereof obtained from a squarer, gives rise to a calibration current, opposed by a constant reference current, for charging a capacitor of a current/frequency converter with a resulting current corresponding to their difference. Two threshold detectors in that converter, responding to a capacitor charge of either polarity beyond a predetermined limit, trigger a monoflop which fully or partly discharges the capacitor and steps the counter forward or backward as determined by a polarity sensor connected across the capacitor. A retriggerable second monoflop, responsive to the trailing edge of each stepping pulse, enables the second-lowest counter stage to be stepped out of turn when these pulses follow one another at high rate.

Abstract: An indicating device for use in a plant for supplying electric current from an alternating current source to a loop circuit having a plurality of serially interconnected primary circuits of a number n of current transformers coupled to an airfield lighting lamp, comprises a transformer coupled to the alternating current source to generate a voltage signal representative of the voltage supplied to the loop circuit, a transformer coupled to the loop circuit to generate a current signal representative of the current flowing in the loop circuit, and an electronic circuit capable of generating in response to the voltage and current signals an output voltage indicative of the number of primary circuits of the loading transformers being uncoupled to their respective secondary circuits. The output voltage is proportional to the voltage integral. ##EQU1## of the loop supply voltage u from the time t.sub.

Abstract: An electronic watthour meter comprising: a pulse width modulation circuit for subjecting a voltage signal, proportional to the load voltage of a power supply line, to pulse width modulation to obtain a pulse width duty cycle signal; a multiplication circuit in which a plurality of analog switches are selectively operated, with the aid of the pulse width duty cycle signal, so that positive and negative DC voltages equal in absolute value are obtained from the product of a voltage signal, proportional to the consumption current of the power supply line, and the pulse width duty cycle signal attributing to the voltage signal proportional to the load voltage; and a dual-slope type frequency conversion circuit for converting the positive and negative DC voltages into a frequency signal.

Abstract: An offset circuit for use in providing an offset signal to an analog-to-digital converter. The analog-to-digital converter has an integrator for performing signal integrate operations and is connected to a digital display. The offset circuit is gated to provide a variable offset current directly to the integrator of the analog-to-digital converter, thereby eliminating adverse loading effects on the high input impedance of the analog-to-digital converter.

Abstract: A method and apparatus are described for detecting faulty insulators used on overhead power transmission lines. The apparatus comprises two contact probes, a capacitance, a blocking resistance and a direct current meter in series between the probes to form an open electrical circuit. Means are provided to prevent discharging of the capacitance while the capacitance is being charged. In the use of the apparatus, the capacitance is charged from a source of high voltage direct current, the discharging of the capacitance to the source is avoided, the contact probes are sequentially applied across insulators and any current flowing across the insulators is recorded by the direct current meter. The sequential application of the contact probes is carried out while the insulators remain in service and the transmission line remains fully energized. The value of the capacitance is such that a large number of insulators can be tested before recharging becomes necessary.

Abstract: An amp-hour meter for a load driven by direct current, such as an electric vehicle, comprises a modulator connected across a resistor in series with the load for amplitude-modulating a pulse train from a multivibrator translated by a demodulator into a unipolar voltage varying with the load current. A sampler converts this voltage into a train of output pulses, generated at a rate proportional to the voltage level, whose count is numerically displayed as a measure of current consumption. The multivibrator, the demodulator, an intervening amplifier, the sampler and the display unit are serially energized with stabilized voltage and reduced current via a supply network connected across the load, this network including a ballast lamp in series with a Zener diode.

Abstract: In a polyphase electric energy meter, voltages of the phases of a polyphase alternating power to be measured are utilized to subject an input pulse signal to be applied to a pulse distributor to pulse width modulation to form polyphase control pulses, which cyclically operate switches provided respectively for the phases so that an operation circuit cyclically receives the voltages and currents of the phases and produces a current output proportional to the sum of the electric powers of the phases.