140 results about "Electrical resistance meter" patented technology

The invention discloses a new method for determining the grounding resistance value of a large-scale grounding system. The new method is characterized in that an apparent resistance calculating curve and an apparent ground resistance measurement curve are simulated through a computer and compared to be coincident, and the grounding resistance value when the large-scale grounding system independently exists can be accordingly and finally determined based on the earth resistivity and the grounding resistance value which are measured on site. The new method has the advantages that utilization of the method is not influenced by the local soil structure on site, and when measurement is not required to be carried out, the distance between the position of a current electrode and the grounding system must be more than 6.5 times the size of a grounding grid. In this way, based on physical conditions such as the site complex terrain structure and multiple in-and-out-line loops of power generating stations and transformer substations, nondestructive measurement on the grounding resistance of the large-scale grounding system can be carried out, and the measurement and calculation accuracy is improved.

The invention discloses a resistance-type nitrogen dioxide gas sensor, and an apparatus manufactured with the sensor. The sensor comprises a gas-sensitive material layer with tungsten oxide as a main gas-sensitive material, and gold conductive electrode plates arranged with an interdigitated structure, wherein the gold conductive electrode plates contact the gas-sensitive material layer. The conductive electrode plates are printed on an alumina planar medium substrate. The back side of the medium substrate is provided with a platinum heating resistor. The sensor is arranged on a pedestal with a small hole. A cap with a ventilating central hole is covered on the pedestal. Platinum conductors are respectively led out from the platinum heating resistor and the interdigitated gold conductive electrodes. The conductors led out from the platinum heating resistor are connected with a heating controlling circuit, and the conductors led out from the interdigitated gold conductive electrodes are connected with a resistance calculating circuit. The apparatus provided by the invention has a simple structure, and employs a novel gas-sensitive material. With the apparatus, an accuracy of nitrogen dioxide volume concentration detection can be improved to a PPB (parts per billion) grade. The apparatus has advantages of good gas selectivity and short reaction time.

The invention discloses an ohm voltage drop automatic compensation rapid scanning circuit based on solution resistance measurement. The circuit comprises a potentiostat, a current/voltage conversion circuit, a digital potentiometer, an amplifying circuit, a first electronic switch, a second electronic switch, a solution resistance measuring circuit and a microcontroller. The microcontroller controls the switching-on of the first electronic switch and the second electronic switch; a solution resistance measuring circuit measures and obtains equivalent resistance in an electrochemical cell; thesolution resistance measuring circuit transmits the obtained equivalent resistance to the microcontroller; the microcontroller calculates a tap coefficient of the digital potentiometer based on the equivalent resistance of the solution; a tap position of the digital potentiometer is adjusted according to the tap coefficient, so the digital potentiometer outputs a feedback voltage signal matched with the tap coefficient; the potentiostat superposes the feedback voltage signal and the scanning voltage signal and then acts on the electrochemical cell, and therefore, the ohmic voltage drop automatic compensation is realized. The circuit has the advantages of no overcompensation problem and higher accuracy on the basis of simplicity and convenience in operation.

The invention relates to a flexible direct-current power transmission system MMC sub-modules key element synchronous online monitoring method. The method comprises the following steps that: S1, an MMC-HVDC system is constructed; S2, sensors are configured to acquire bridge arm voltage, bridge arm current and sub-module capacitor voltage; S3, a sub-module IGBT, diode and capacitor on-line monitoring mathematical model is constructed; S4, IGBT on-state voltage bias, diode on-state voltage bias, diode on-state resistance and a capacitor capacitance value are obtained online through a Kalman filtering algorithm; S5, estimated IGBT on-state voltage is calculated according to the IGBT on-state voltage bias and IGBT on-state resistance, and on-state voltage and on-state resistance are calculated;and S6, the obtained IGBT on-state voltage, the diode on-state voltage, the diode on-state resistance and the capacitor capacitance value are compared with set parameter threshold values, and aging identification and residual life estimation are carried out on sub-modules. With the method of the invention adopted, the synchronous on-line monitoring of semiconductor devices and capacitors in a monitoring MMC can be realized.

The invention relates to a device for measuring impact force of tows and airflow in a flash spinning process. A deflection device in the prior art is improved into a combination of an insulating bottom plate and a pressure receptor from a deflection plate. Resistance change generated after the pressure sensor made of piezoresistive materials is subjected to impact force of tows and airflow is measured through an electric brush, a wire and a resistance meter, the impact force is obtained, the compression-resistant distance of the insulation bottom plate is adaptively changed, therefore, the impact force is stabilized, the degree of uniformity of dispersion of a tow net is improved, and finally, the unit mass uniformity of the flash spinning non-woven fabric is improved.

The invention discloses a method for calculating the induced current of a metal sheath of a cable under multi-phase and multi-point grounding, which comprises the steps of S1, calculating and measuring the resistance R and reactance X of the metal sheath of the cable, the grounding resistance R1 and R2 at two ends of the cable and the earth leakage resistance Re; S2, calculating the length proportions [alpha]i, [beta]j and [gamma]t of each small section to the total line, and measuring fault grounding resistance Rki, Rgj and Rft; S3, calculating the metal sheath reactance Zki, Zgj and Zft of each section of the branches of the three-phase cable, and calculating circuit induced electromotive forces Uki, Ugj and Uft, which are generated by wire core current of the three-phase cable, of eachsection; S5, calculating induced electromotive forces Uki', Ugj' and Uft', which are generated by circulating current in the sheath of the three-phase cable, of each section; and S6, calculating induced current Iki, Igj and Ift of each section of the branches of the three-phase cable. The induced current value on each section of the cable under the multi-phase and multi-point grounding condition can be conveniently calculated according to the invention.

The invention provides a storage battery starting performance prediction method, a storage medium and electronic equipment, and the method comprises the steps: obtaining the current voltage of a storage battery and the current current corresponding to the current voltage, and enabling the current voltage to be in positive correlation with the current current; inputting the current voltage and thecurrent current into a preset resistance model for calculating the ohmic resistance of the storage battery to obtain the current ohmic resistance; calculating the current lowest end voltage of the storage battery according to the current ohmic resistance; and judging the starting performance of the storage battery according to the current lowest end voltage. By implementing the method and the device, the SOF of the storage battery can be calculated no matter whether the storage battery is large in charge-discharge current or small in charge-discharge current, so that the calculation precisionof the SOF of the storage battery is improved, the SOF of the storage battery is updated in time, and the judgment reliability is improved.

The invention provides a method for testing the tension sensitivity of a stress self-sensing cement-based material, and belongs to the field of cement material performance testing. The method comprises the following steps: pouring prepared composite cement paste into an 8-shaped mold, inserting at least two metal electrodes into the composite cement paste in a parallel arrangement mode, and after a test block is hardened, performing mold removal and maintenance; then testing the initial resistance R1 of the test block; carrying out an axis tensile test on the test block, collecting the resistance R2 between the electrodes in real time in the tension loading process, and calculating the real-time resistance change rate = (R2-R1)/R1; and finally, determining the relationship between the tensile force for judging the quality of the tension-sensitive property and the resistance change rate. The method has the advantages of high accuracy, simplicity, convenience and the like, and the data acquisition and processing of the resistance test have the advantages of simple and reliable circuit, digitization, high stability, low cost, real-time monitoring and the like.

Methods and electronic devices for estimating state of charge (SOC) of a battery pack. Various embodiments provide a model comprising an (electrical) equivalent circuit model, an electrochemical (thermal) model, and a (convective) thermal model. The model estimates parameters pertaining to each cell of the battery pack individually, and determines the variations in the values of the parameters among each of the cells of the battery pack. The parameters include capacity, temperature current, voltage, and SOC. The parameters are computed based on at current drawn by the battery pack, electrochemical parameters, thermal parameters, and cell internal and connection resistances of the individual cells. Various embodiments compute battery pack uptime, chargeable capacity of the battery pack and SOC of the battery pack, based on the values of the parameters.

The present invention provides a method for testing a TMR element including a step of measuring a plurality of resistances of the TMR element by feeding a plurality of sense currents with different current values each other through the TMR element, a step of calculating a ratio of change in resistance from the measured plurality of resistances of the TMR element, and a step of evaluating the TMR element using the calculated ratio of change in resistance.

A quantum Hall resistance apparatus is to improve resistance standards and includes a substrate, a graphene epitaxially grown on the substrate and having a plurality of first contact patterns at edges of the graphene, a plurality of contacts, each including a second contact pattern and configured to connect to a corresponding first contact pattern, and a protective layer configured to protect the graphene and to increase adherence between the first contact patterns and the second contact patterns. The contacts become a superconductor at a temperature lower than or equal to a predetermined temperature and under up to a predetermined magnetic flux density.

The invention relates to an aerospace current-carrying slip ring temperature rise modeling method based on multi-physics field coupling, and belongs to the technical field of conductive friction pairs. The method comprises the following steps: firstly, calculating a theoretical contact region of a brush contact and a confluence disc, and calculating contact resistance and contact resistance heat of the brush contact and the confluence disc based on conductive spots; in addition, the resistance Joule heat is calculated based on the resistance of the bus plate, and the friction heat between the sliding contact and the bus plate is further calculated. and finally, the total heat generated by the contact resistance heat, the confluence disc resistance Joule heat and the friction heat is synthesized, the heat dissipation rate is calculated through heat radiation, and the heat dissipation rate and the generated heat reach dynamic balance to calculate the steady-state temperature. Compared with a previous experimental measurement method, the method has the advantages that the coupling relation among a thermal field, a force field and an electric field is explored, modeling is performed on a temperature rise mechanism of the current-carrying slip ring for spaceflight, and factors influencing the temperature of the current-carrying slip ring are analyzed, so that the method has the advantages of saving a large amount of funds and time and improving the working reliability of the satellite current-carrying slip ring.

Apparatus for respiratory anaesthesia of a patient by administration of a gas containing gaseous xenon, with a main gas circuit which is open or closed and has an inhalation branch and an exhalation branch, means for supply of gaseous xenon to the inhalation branch of the main circuit, and means for determining the xenon concentration. The means for determining the xenon concentration comprise at least one hot-wire sensor having at least one electrically conducting wire in direct contact with the gaseous flow containing the xenon, calculating means that cooperate with the hot-wire sensor(s) in order to determine the xenon concentration (Xe %) in the flow, means for generating an electrical current in order to generate a current in at least one hot wire, and means for voltage measurement that can measure at least one voltage value at the terminal of at least one hot wire or at least one resistance arranged in series with at least one hot wire. The calculating means cooperate with the voltage measurement means in such a way as to determine the xenon concentration (Xe %).

The invention provides a measurement and remote test combined power system voltage quality test system and a method, and belongs to the field of voltage quality detection systems. In the method, a database, a control module, an information acquisition module, a measurement module and a proofreading module are included, the information acquisition module stores acquired information of line length and cable type in the database, the control module extracts the information of various sections of cables reaching a user from the database and calculates the resistance of a line through the measurement module, the control module calculates the voltage drop of the line according to the resistance of the line, calculates the voltage of a switch at the tail end of the line according to the voltage drop of the line, and acquires the actual voltage of the switch at the tail end according to an electric energy meter at the tail end of the line, the actual voltage is proofread by the proofreading module, the quality of a power supply is fed back, and that whether the voltage quality of the power supply of the user is normal or not is detected.

The invention discloses a method for detecting the capacity of a single polar plate of a storage battery. The comprises the following steps of: connecting a positive tab of the storage battery with the output end of a first constant value resistor, and connecting each negative tab with the input end of a second fixed-value resistor; connecting a positive electrode output line of a storage battery charging and discharging machine to the input end of the first constant value resistor, and connecting a negative electrode output line of the storage battery charging and discharging machine to the output end of the second constant value resistor; starting a discharging mode of the storage battery charging and discharging machine , and starting a voltage acquisition device to detect the voltage on the first and second constant value resistors; and calculating the discharge current according to the voltage and the constant resistance, and obtaining the capacity of the single polar plateaccording to the discharge current and the discharge time. By detecting the capacity of the single-grid polar plate in the storage battery, the deviation of the thickness, the weight and the like of the single polar plate is comprehensively judged, and the measurement precision is improved.

The invention discloses a grounding fault transition resistance calculation method for a neutral point through a combined grounding mode. The method comprises steps that in a grounding mode that a neutral point of a hydraulic generator is connected with an inductor in parallel through a load resistor at the low-voltage side of a distribution transformer (a combined grounding mode for short), on the basis of single-phase grounding protection of an external 20Hz power supply type stator, grounding fault transition resistance is calculated by adopting an admittance criterion, the influence of equivalent parameters of a generator grounding device on calculation of a primary side grounding fault resistance value through current and voltage measured by a secondary side in the admittance criterion is analyzed, and the method for calculating the grounding fault transition resistance of the neutral point of the hydraulic generator in the combined grounding mode is obtained. According to the method, by correcting the admittance criterion, accuracy of fault resistance calculation can be improved, and sensitivity of fault detection is further improved.

The invention discloses a charging pile insulation detection system and method. The system adopts a charging pile insulation detection circuit to carry out insulation detection on a charging pile, and comprises a bus voltage measurement module which is used for measuring the voltage to ground of a positive bus, the voltage to ground of a negative bus and the voltage between the positive bus and the negative bus of the charging pile insulation detection circuit; the insulation resistance calculation module is used for calculating positive bus-to-ground insulation resistance and negative bus-to-ground insulation resistance in the charging pile insulation detection circuit according to the positive bus-to-ground voltage, the negative bus-to-ground voltage and the voltage between the positive bus and the negative bus; and the insulation state judgment module is used for judging the insulation state of the charging pile according to the ground insulation resistance of the positive bus and the ground insulation resistance of the negative bus. The technical problem of insulation detection of the charging module of the charging pile in the prior art is solved.