5422results about "Measurement using digital techniques" patented technology

A self-powered current monitor for monitoring current in electric power systems. Various data relating to input currents may be displayed, such as current magnitude, current demand, and harmonics levels. Operating power is derived from one or more of the input currents. The power supply configuration may include a burden-reducing means to reduce the burden on input current sources during sampling of the input currents. The self-powered current monitor (1) includes a power supply section (3), input resistors (R1 and R3), an analog-to-digital converter circuit (5), a microprocessor circuit (6), a memory circuit (9), and a display circuit (7). Optional features include a burden-reducing circuit (2), input circuit protective elements (D1, D2, D3, D4, R2, and R4), an amplifier circuit (4), a user interface circuit (10), and an interface circuit (8) for communication to other equipment.

The present invention relates to an electronic circuit and an array of such circuits for precisely measuring small amounts or small changes in the amount of charge, voltage, or electrical currents. One embodiment of the present invention provides an electronic circuit for measuring current or charge that can be used with a variety of sensing media (including high impedance sensing media) that produce a signal by either charge or current production or induction in response to physical phenomena occurring within the sensing media. In another embodiment, the voltage level (bias) of either the sensing or reference electrode can be switched relative to the other upon receipt of a triggering pulse. This changes the polarity of the electric field to cause charge of the opposite polarity to be driven to the sensing electrode, thereby eliminating the need to electrically connect a discharge path to the sensing electrode to clear the charge accumulated at the sensing electrode. This can be supplemented by capacitively coupling a compensation signal to the sensing electrode to cause the amplifier output signal to lessen in magnitude below a threshold level that permits additional charge or current measurements of the same polarity before performing bias reversal. Alternately or in combination with bias reversal and capacitive compensation, sensor performance can be improved by minimizing inaccuracies caused by leakage currents or current drawn from the sensor. Other described methods of reducing leakage currents that can be used alone or in combination with the aforementioned features include the use of guard rings, physical switches or relays, the controlled creation of charges or currents of a specific polarity in a specific region of the sensing medium, controlled leakage over the surface of an insulator, and controlling the environment in which the circuit operates.

An electrical power (AC/DC) monitoring system remotely monitoring batteries and electrical power systems through a call center, providing continual monitoring, monthly reports, near real time viewing and service response. Modular by design, a plurality of individual input modules, which receive an analog voltage input, convert this signal to a digital format and send the digital signal to a central control which collects the data, then, at scheduled intervals, sends the collected data to a web server which contains the main software for the system. This software performs data comparisons, charts trends, predicts failures, plans and schedules service visits, then archives the data for future references. Alarm notifications are provided to the customer via Email, office phone (land line), cell phone (wireless), PDA, pager, etc. and can also be sent to a service provider to initiate the service response.

A switched mode power can use a digital controller to control the switching of the at least one switch of the switched mode power supply. The current through the power inductor can be estimated using a self-tuning digital current estimator.

Dynamic thresholds statistically derived are used to define normal conditions at a specific site in an electric power distribution system. High and low and/or caution and alarm thresholds for various parameters are generated as multiples of the standard deviation of the long-term average of measured values calculated from samples gathered over repetitive intervals, such as ten minutes. Weekly averages are used until sufficient data has been gathered to maintain a running one year average.

Conventionally, there is a problem that it is impossible to provide an analog signal detecting circuit having high reliability and long lifetime under a bad environment since a photocoupler is used for electrical insulation of a digital signal. Then, an analog signal detecting circuit is provided with a carrier wave generating unit for generating a carrier wave, a pulse width modulating unit for pulse width modulating an analog signal inputted from the signal input terminal by using the carrier wave generated by the carrier wave generating unit and for outputting a digital signal, a reverse level shift HVIC for transmitting the digital signal from one power supply system to the other power supply system, and a demodulation unit for demodulating the digital signal transmitted to the other power supply system into an analog signal and for outputting it to a signal output terminal. As a result, even in the case where reference potentials are different from each other at signal input/output terminals, an analog signal can be detected.

A composite power quality indication generated from user weighted statistical contributions of selected system parameters provides an overall indication of power quality in an electric power distribution system. The user defined weightings are maintained over time by continually updating sensitivities that normalize the component contributions to the composite power quality indication. The current composite power quality indication is displayed in relation to its long-term mean and to dynamic thresholds determined as multiples of the standard deviation of the long-term mean.

A current diagnosing device for monitoring the state of a current transformer comprises a state-detecting grounded resistor which is arranged between an output end of a secondary coil of the transformer and a signal-regulating circuit and one end of the state-detecting grounded resistor is grounded. The signal-regulating circuit connected between analog digital (AD) pins of the transformer and a central processing unit is a proportional integral circuit and is used for converting a main circuit current signal output by the current transformer into an alternating voltage signal and regulating the amplitude and phase of the signal. The central processing unit performs the AD conversion on the voltage signal output by the signal-regulating circuit. When the circuit of the current transformer is broken, the signal-regulating circuit outputs a fixed direct-current voltage signal which surpasses a set threshold value deviating from the reference voltage Vref. When the value of the counter reaches the preset period and the average values of all periods surpass the threshold value, the central processing unit gives a failure warning and instructs a tripping driving unit to drive a breaker to do disconnecting operation and the display unit displays the current and failure information of the main circuit.

A Three-phase Power Signal Processor (TPSP) is disclosed for general three-phase power system applications. The TPSP is developed based on the concepts from adaptive filter and dynamical systems theories. The structure of the TPSP is unified as it provides a multiplicity of the signals and pieces of information without the need to change, modify, or enhance the structure or to impose excessive computational time or resource requirements. The presented TPSP receives a set of three-phase measured signals, which can be voltage, current, magnetic flux, etc, and provides (1) the instantaneous and steady-state symmetrical components, (2) the fundamental components, (3) the peak values (magnitudes) of the symmetrical components, (4) the frequency and its rate of change, (5) the synchronization signal(s) and zero-crossing instants, (6) the phase-angles of the symmetrical components, and (7) the disturbance signatures. Two or more TPSP units, when properly augmented, further provide (8) the individual harmonic components, (9) the inter-harmonics, (10) the instantaneous real and reactive current components, (11) the total harmonic distortion, dc-offset, and power factor. The TPSP can serve as the building block for various signal processing requirements encountered in the context of power system applications including power systems control, protection, monitoring, and power quality.

The invention discloses a kind of current sensor, the character lies in: the feedback windings in the two symmetrical channels are connected in series, one end is accessed to the ground, the other end is accessed to one end of the sample resistance; the output of the symmetrical Hall elements are amplified, then carries on filter, voltage-current transform, current amplifying process, the output end is accessed to another end of the sample resistance, the detected voltage signal detected at two ends of the sample resistance; it also includes Rogowski coil, the two ends of the coil are connected in parallel to the sample resistance, the detected voltage signal of sample resistance is amplified, filtered and integral amplified, and transmitted to the computer; the computer process the data and transmits the detected current to the monitor to be displayed; the precision is higher than 0.5%. The power consumption is small, the temperature additional error is less than 0.1%/10 degrees centigrade, the structure is simple, and easy to be assembled, debugged and maintained.

The invention relates to a zinc oxide arrestor on-line monitoring system which comprises a microprocessor which is respectively connected with an A/D converting unit, a lightning stroke counting module and a GPRS communication module; the A/D converting unit is respectively connected with a leakage current sampling module and a voltage sampling module; the structure of the microprocessor comprises input/output interfaces, a counter and a serial communication interface; the input/output interfaces are connected with the A/D converting unit; the counter is connected with the lightning stroke counting module; the microprocessor is connected with the GPRS communication module; the microprocessor adopts a FPGA chip EPIC6Q240C8. The monitoring system dynamically monitors the insulating property of the zinc oxide arrestor under the operating voltage; the test results are accurate and reliable; the testing process is simple; and the test period is short; the zinc oxide arrestor on-line monitoring system is not easy to be affected by artificial and external factors, can provide long term data information of operation and performance deterioration of the zinc oxide arrestor, and has better practical value.

The invention discloses an on-line positioning method of a section with low-current ground faults and a system based on the positioning method. The method and the system are suitable for a neutral ungrounded power grid of 3-60kV. Under the operation condition of a line with single-phase ground faults, the phasor information of a zero-sequence voltage and the amplitude and phasor information of a zero-sequence current of the line are measured, and the section position of a fault point is determined according to the amplitude and phase information. The accuracy and rapidity of positioning are fully ensured, and the on-line positioning problem of single-phase ground faults of the neutral ineffectively grounded power grid and the monitoring problem of short-circuit faults between lines are effectively solved.

The invention discloses a current calibration coefficient measurement device, a measurement method, a current detection device and a detection method. The measurement device comprises an upper computer and a current source, wherein the current source is serially connected with a shunt of a to-be-calibrated current detection device. The current detection device also comprises a voltage acquisitionunit for acquiring voltage analog signals at two ends of the shunt, a voltage analog-digital conversion unit for carrying out analog-digital conversion on the voltage analog signals to obtain a voltage value and a current calculation unit for calculating a detection current value according to the voltage value and the nominal resistance of the shunt. The upper computer is used for controlling thecurrent source to output current at a specified current value, and according to the specified current value and the detection current value calculated by the current calculation unit, a current calibration coefficient is calculated and obtained. According to the measurement device disclosed in the embodiment of the invention, a brand new current detection device current calibration coefficient measurement scheme is provided, a current calibration basis is provided for current detection by the current detection device, and the current detection precision is improved.

The battery charge/discharge current detection apparatus has a power supply circuit powered by a battery mounted on a vehicle and configured to detect a charge/discharge current of the battery by use of a current detecting resistor connected between a negative terminal of the battery and a ground. The battery charge/discharge current detection apparatus includes a first function of detecting a voltage across the voltage detecting resistor, a second function of detecting a charge/discharge current of the battery on the basis of the voltage detected by the first function, a third function of detecting presence of an abnormality of the current detecting resistor, and a fourth function of informing an abnormality detected by the third function to the outside. The battery-side negative terminal of the power supply circuit is connected to the negative terminal of the battery.

The invention discloses a weak current detection device for radiation detection, which is used for detecting large dynamic weak current and requires recording and displaying measured data in real time. The device comprises a DC power module, a weak current amplifying and I/V switching circuit, an A/D conversion circuit, a central control unit, a range selection switching circuit and a user terminal, wherein the central control unit is used for finishing the functions of data processing, range switching and data communication; and the range selection switching circuit realizes automatic range selection by selecting a feedback channel of a feedback network. The weak current detection device realizes automatic range switching, adopts a T-shaped resistance network structure in a feedback network of the weak current amplification and an I/V switching circuit U2, improves the equivalent resistance of the feedback network and avoids the temperature drift and capacitive reactance influence brought by high impedance generally. Therefore, the technical problems that the conventional weak signal measurement equipment has low range, slow response, low resolution, and the like, so that the precision reaches 0.1pA or below and the resolution is 10fA.

The invention relates to a life tester for an alternating-current contactor and a control method thereof. The life tester consists of a test control cabinet, a specimen cabinet, a 1/6Ue power supply cabinet and a load cabinet, wherein the test control cabinet comprises an industrial personal computer, a driving circuit and a contact state detection circuit; the specimen cabinet comprises a first accompanied specimen, a contactor specimen and a first breaker; the 1/6Ue power supply cabinet comprises a second accompanied specimen and a second breaker; and the load cabinet comprises a load circuit. The life tester is controlled by the industrial personal computer, so a life test of the alternating-current contactor can be completed automatically and accurately, and the automation level of the life test is improved; and four electrical life tests of a switch-on test, a break-off test, a dead load test and a variable load test of the alternating-current contactor can be performed, and a mechanical life test of the alternating-current contactor also can be performed. The life tester has an integral data protection function, namely test data is not lost in case of unexpected outage, the collected test data is not damaged after the power supply restores, and the test data is saved perpetually.