Lead Wire Resistance Research Articles

Direct interface circuits for resistive sensors affected by lead wire resistances

This article proposes two novel circuits for the digital readout of resistive sensors with parasitic series resistances caused by the lead wire needed to connect remote sensors. Both circuits are based on so-called direct interface circuits (DICs). These circuits perform a resistance-to-time-to-digital conversion by adding some external components to a digital processors (DP). The new circuits are very simple since they only use a capacitor and two or three resistors, depending on the proposal. A single discharging of the capacitor provides two or three time measurements to estimate the resistance of the sensor, eliminating the influence of lead wire resistances. Using a single discharging process simultaneously reduces error sources, measurement time, and energy consumption. A circuit that uses an FPGA as DP to estimate resistances corresponding to several thermal sensors presents systematic errors below 0.15% or 0.12%, depending on the proposal, for a maximum measurement time of 1.09 ms.

A Procedure for Precise Determination and Compensation of Lead-Wire Resistance of a Two-Wire Resistance Temperature Detector.

A procedure for the precise determination and compensation of the lead-wire resistance of a resistance transducer is presented. The proposed technique is suitable for a two-wire resistance transducer, especially the resistance temperature detector (RTD). The proposed procedure provides a technique to compensate for the lead-wire resistance using a three-level pulse signal to excite the RTD via the long lead wire. In addition, the variation in the lead-wire resistance disturbed by the change in the ambient temperature can also be compensated by using the proposed technique. The determination of the lead-wire resistance from the proposed procedure requires a simple computation method performed by a digital signal processing unit. Therefore, the calculation of the RTD resistance and the lead-wire resistance can be achieved without the requirement of a high-speed digital signal processing unit. The proposed procedure is implemented on two platforms to confirm its effectiveness: the LabVIEW computer program and the microcontroller board. Experimental results show that the RTD resistance was accurately acquired, where the measured temperature varied from 0 °C to 300 °C and the lead-wire resistance varied from 0.2 Ω to 20 Ω, corresponding to the length of the 26 American wire gauge (AWG) lead wire from 1.5 m to 150 m. The average power dissipation to the RTD was very low and the self-heating of the RTD was minimized. The measurement error of the RTD resistance observed for pt100 was within ±0.98 Ω or ±0.27 °C when the lead wire of 30 m was placed in an environment with the ambient temperature varying from 30 °C to 70 °C. It is evident that the proposed procedure provided a performance that agreed with the theoretical expectation.

Performance enhancement and fault identification using Kalman filter in a resistive temperature sensor interface

In recent times, smart resistive sensor interfaces are popular. A smart two-wire interface of Resistance Temperature Detector (RTD) with fault identification feature is proposed in this study. In this method, a constant floating current source is used along with a microcontroller and 16-bit ADC. Further, Finite Impulse Response (FIR) filter and Kalman filter were implemented to filter noise. The results obtained were encouraging. Evaluation of the proposed model was undertaken and a maximum percentage of absolute error of 0.11% was observed. Further, without any additional measurements, a model-based fault identification using Kalman filter was also proposed to locate faults in the sensor and lead-wire resistances. A deliberate sensor fault and increase in lead-wire resistances were introduced to check the performance. The proposed system works reliably and promises fault identification.

Lead-Wire-Resistance Compensation Technique Using a Single Zener Diode for Two-Wire Resistance Temperature Detectors (RTDs)

In remote measurement systems, the lead wire resistance of the resistance sensor will produce a large measurement error. In order to ensure the accuracy of remote measurement, a novel lead-wire-resistance compensation technique is proposed, which is suitable for a two-wire resistance temperature detector. By connecting a zener diode in parallel with the resistance temperature detector (RTD) and an interface circuit specially designed for it, the lead-wire-resistance value can be accurately measured by virtue of the constant voltage characteristic of the zener diode when reverse breakdown occurs, and compensation can thereby be made when calculating the resistance of RTD. Through simulation verification and practical circuit testing, when the sensor resistance is in 848–2120 Ω scope and the lead wire resistance is less than 50 Ω, the proposed technology can ensure the measuring error of the sensor resistance within ±1 Ω and the temperature measurement error within ±0.3 °C for RTDs performing 1000 Ω at 0 °C. Therefore, this method is able to accurately compensate the measurement error caused by the lead wire resistance in two-wire RTDsand is suitable for most applications.

Enhanced Interfacing o f Single Element Resistive Sensor w ith Microcontroller

Resistive sensors can be used in a single element, differential and bridge forms. Resistive sensors have wide applications in industries. When the resistive sensor is directly connected with the microcontroller large amount of error arises due to lead wire resistance and microcontroller port pin resistances. Here, an enhanced interfacing of single element resistive sensor with a microcontroller scheme is proposed to compensate the error due to lead wires and port pin resistances. This scheme follows three discharge cycles for the measurement of resistances of the resistive sensor. The time taken for each discharge cycle is noted. From the time taken for the three discharge cycles, the resistance of the resistive sensor is directly calculated. Since the resistances due to lead wires and internal port pin resistances are corrected, the unknown temperature measurement is done accurately.

Enhanced Microcontroller Interface of Resistive Sensors Through Resistance-to-Time Converter

Systems using microcontrollers make the interface of a transducer with the digital world much easier. They build smart, lucid, compact, cheap, and less power consuming electronic interfaces. Limited acquisition time is critical for many industrial applications. Single-element resistive sensors are used on a large scale. An attempt has been made to reduce the acquisition time of the measuring system compared to the existing work which converts the change in sensor resistance to the change in time with three charge–discharge cycles. Efforts have been made in this paper to reduce this to two charge–discharge cycles. The proposed work also compensates the errors due to lead wire resistance, the change in lead wire resistance, port pin resistances, and varying ambient temperature with reduced acquisition time. The mean of absolute errors, standard deviation, integral squared error (ISE), nonlinearity, and hysteresis of the proposed method have been computed. Simulation and experimentation study of the proposed system provided encouraging results. The mean of absolute errors and standard deviation of the proposed method in the simulation were 0.07 and 0.08 $\Omega $ , respectively. Furthermore, during experimentation, the values of the mean of absolute errors and standard deviation were 0.11 and 0.11 $\Omega $ , respectively. ISE was found to be 0.09 and 0.19 in simulation and experimentation, respectively. The proposed two-cycle method has an acquisition time of only 60% of the three-cycle method with no reduction in performance.

Characterization of the stimulus waveforms generated by implantable pulse generators for deep brain stimulation

ObjectiveTo determine the circuit elements required to theoretically describe the stimulus waveforms generated by an implantable pulse generator (IPG) during clinical deep brain stimulation (DBS). MethodsWe experimentally interrogated the Medtronic Activa PC DBS IPG and defined an equivalent circuit model that accurately captured the output of the IPG. We then compared the detailed circuit model of the clinical stimulus waveforms to simplified representations commonly used in computational models of DBS. We quantified the errors associated with these simplifications using theoretical activation thresholds of myelinated axons in response to DBS. ResultsWe found that the detailed IPG model generated substantial differences in activation thresholds compared to simplified models. These differences were largest for bipolar stimulation with long pulse widths. Average errors were ∼3 to 24% for voltage-controlled stimulation and ∼2 to 11% for current-controlled stimulation. ConclusionsOur results demonstrate the importance of including basic circuit elements (e.g. blocking capacitors, lead wire resistance, electrode capacitance) in model analysis of DBS. SignificanceComputational models of DBS are now commonly used in academic research, industrial technology development, and in the selection of clinical stimulation parameters. Incorporating a realistic representation of the IPG output is necessary to improve the accuracy and utility of these clinical and scientific tools.

Improved Single-Element Resistive Sensor-to-Microcontroller Interface

Direct resistive sensor interface to a microcontroller has several advantages but has one prominent disadvantage, namely, the measurement is affected by the resistances of: 1) wires that connect the sensor to the port pins and 2) the internal resistances of the port pins of the microcontroller. A direct sensor-to-microcontroller interface scheme that compensates the effect due not only to resistances of lead wires but also the effect of microcontroller port pin’s internal resistance and any offset present in those pins is presented in this paper. Since the resistances of lead wires are compensated, automatic temperature compensation (temperature effect of lead wires) is also obtained. Simulation study and results obtained from a prototype built and tested establish the efficacy of the proposed method. A maximum error of 0.06% was observed from the prototype developed, when it was tested under room temperature, after interfacing it with the sensor Pt100, with a lead wire resistance $R_{\mathrm {LD}} = 21~\Omega $ . The error increased to a maximum of 0.08%, when the $R_{\mathrm {LD}}$ varied from 0 to $100~\Omega $ . When the same prototype was tested under elevated room temperature of 30 °C to 100 °C, the maximum error observed was 0.18%.

The Research on the Integrational Measurement Device of Grounding Resistance

Measuring grounding resistance is the only basis to judge the grounding of electrical equipment is good or not. Aim at the trouble on retracting and releasing of the current lead wire and voltage lead wire;the insecure connection Lead wire and grounding resistance tramegger、grounding crooked chisel and so on;The hectic trouble such as placing or picking the grounding resistance testing equipment, we developed the integrational measurement device of grounding resistance. It mainly introduces the structure and design principle of the device, and provides the related technical essentials. Combined with the actual application,and demonstrates its convenience and flexibility by the force of contrast; Through the case analysis, fully demonstrates the device is feasible、creative and rationality.

A Microcontroller Sensor Interface Suitable for Resistive Sensors with Large Lead Resistance

Abstract A direct resistive sensor interface to a micro- controller reported earlier, works well only if the sensor element is very close to the micro-controller pins. If the sensor element is at a distance from the micro-controller then the lead resistance due to connecting wires between resistive sensor element and the modified scheme of direct sensor interface to micro-controller is presented here. In the proposed scheme, the effect of lead resistances is compensated and thus the proposed direct resistive sensor interface to a micro-controller works well even if the sensor is kept at distance and connected through long connecting wires. Since the lead wire resistance is compensated, automatic temperature compensation (temperature effect of lead wires) is obtained. The results obtained from simulation and experimental results recorded from a prototype of the proposed scheme establishes the effectiveness of the proposed method in eliminating the effect of lead resistance in the output. Worst-case error noted in the simulation output was < ± 0.23 % and the worst-case error of the prototype unit was found to be < ± 0.33 %.

Temperature Measurement with High Accuracy

Calibration of general temperature sensor, platinum resistor is done with measuring its zero resistance and dispersity of linear system and compensating. Accurate constant current source is used to provide platinum resistor sensor power and four-wire measuring method is designed for self-compensation of lead wire resistance. With amplifying the changing signal of platinum using amplifier of high precision and low temperature drift, and MCPU digital filtering, highly accurate temperature measurement result is got finally.

Thermal Expansion Measurements Using the Strain Gauge Technique with Kelvin Double Bridge

The strain gauge technique is known to be very useful for thermal expansion measurements under pressure. However, there is a problem to be resolved in this method; Wheatstone bridge that is conventionally employed in this technique is subject to a spurious effect resulting from lead-wire resistances. Here we report that such the effect is remarkably suppressed by using Kelvin double bridge instead of Wheatstone bridge. As an example of this application to heavy fermions, we present results of thermal expansion measurements of UGe 2 and ZrZn 2 that have been attracting much attention in the field of strongly correlated electron physics.

Temperature Cycle Measurement System Based on Single Chip Computer

This thesis introduces a low cost and high precision temperature cycle measurement system with adoption of PT100 as temperature sensor, with single chip computer as the core. The method of sub-three-wire connection is proposed for engineering practice, then, can eliminate the effects of lead wire resistance and simplify the external cable connection. We discuss and research circuit component selection, circuit design, improving system reliability, and a software method of piecewise linearization process is adopted, thus we ensure exact and reliable measure and the system characteristic of low cost and high precision.

DC Bus Compensation for a Sinusoidal Voltage-Source Inverter With Wave-Shaping Control

This paper presents a study on the effects of different parameters on the dc bus voltage of a single-phase voltage-controlled voltage-source inverter (VCVSI) with conventional load-voltage root-mean-square (rms) feedback control and a wave-shaping controller (WSC). It is shown that the load-voltage rms feedback control and the WSC require compensation for the fluctuations in the dc bus voltage caused by the battery and lead-wire resistance and the lead-wire inductance. The dc-bus-voltage compensation is shown to provide performance improvements, including better load-voltage regulation and less load-voltage distortion. The mathematical modeling, computer simulations, and experimental results based on a 2-kVA single-phase full-bridge VCVSI are presented.

A new hardware approach for the linearization of remote thermistor temperature-voltage characteristic

Present active circuitry for the linearization of thermistor temperature-voltage characteristic has drawbacks concerning the effect of connecting lead wire resistances, self-heating effect due to continuous excitation current in the sensing thermistor, ambient temperature variations and temperature dependent reverse saturation current both in transistorized logarithmic amplifier and Field Effect Transistor. In order to overcome these problems, a new hardware approach for the linearization of remote thermistor has been proposed. The experimental results show the good linearity throughout the temperature range of thermistor.

An improved lead compensation technique for three-wire resistance temperature detectors

An improved lead resistance compensation technique for use with three-wire resistance temperature detectors is presented. The present practice of using the three-wire concept in an unbalanced bridge to provide signal to direct reading instruments produces nearly 1% error for a lead resistance as low as 1 /spl Omega/. In contrast, the new method limits the error to below 0.1% with much higher lead wire resistances.

Electrical resistivity measurements of conductors in the diamond-window, high-pressure cell

The electrical resistance measurement of metallic conducting materials can be done in situ in a diamond-window, high-pressure cell with a four-lead arrangement designed to avoid contact and lead-wire resistances. Variants of the general method include designs for long (several cm) and short (less than 1 mm) length of samples material, and for the use of solid and fluid pressure-transmitting media.

Strain-gage Circuit Calibration Error

Increasingly, constant-current potentiornetric circuitry is used to eliminate lead-wire resistance effects in straingage applications. While lead resistances can be ignored during data taking, such resistances must be properly considered during shunt calibration to avoid potentially large errors.

An Electrically Calibrated Plethysmograph for Direct Measurement of Limb Blood Flow

This paper describes an electrically calibrated plethysmograph which may be used with all lengths of mercury-in-rubber strain gauges. Due to the very low resistance of these strain gauges, electrical calibration of previously available plethysmographs has suffered from errors caused by lead-wire resistance. The present instrument eliminates lead-wire errors by a design which effectively places the strain gauge at the corners of the measurement bridge. Linearity of the output for large changes in gauge resistance has been insured by the incorporation of a constant-current bridge supply.

放電研摩に関する研究 (第 2 報)

The single-discharge phenomena on the stationary and rotating electrodes are investigated to clarify the mechanism of the electric-discharge grinding.The discharge-current is measured by inserting the detector in the discharge circuit. Influences of the electro-static capacity of the condenser, the lead wire resistance and the inductance in the discharge circuit upon the maximum value of the discharge-circuit and the discharge duration are clarified. As the result of investigating the maximum current and the crater-diameter, it is reasonable to consider that the energy density of the discharge column at the time of the maximum current is constant.In the single-discharge on the rotating electrode, it is experimentally confirmed that the discharge column moves on the electrode and the workpiece with the speed of one-half velocity of the moving electrode.The movement of the discharge column and the forming process of the crater are investigated and it is clarified that it is reasonable to consider that the discharge column does not lengthen or curve but stands vertically on the surfaces of the workpiece and the electrode.The single-discharged crater shape and the profile curve are determined assuming that the heat source moves on the electrode and the workpiece and they correspond with the actual ones.