voltage measurement techniques

The design of the saturable inductor current sensor is similar to that of a closed-loop Hall-effect current sensor; the only difference is that this method uses the saturable inductor instead of the Hall-effect sensor in the air gap. A specified forward current (from a constant current source) is passed through the device and the voltage developed across it is measured on a high-impedance voltmeter. 4). Digital multimeters (DMMs) measure two or more electrical values, such as voltage, amperage, or resistance. LearnEngineering team try to Helping the students and others who cannot afford buying books is our aim. The high-performance ground tester replaces DET2/2 that has been widely used in the industry for 25 years. Hall effect sensors are devices based on the Hall-effect, which was discovered by Edwin Hall in 1879 based on the physical principle of the Lorentz force. By employing a so-called isolation amplifier, electrical isolation can be added. where A is the cross-sectional area of the coil and N is the number of turns. The MOSFET consists of thousands of parallel transistor cells that reduce the on-resistance. Change in the saturation level of a saturable inductor will alter core’s permeability and, consequently, its inductance L. The value of saturable inductance (L) is high at low currents (based on the permeability of the core) and low at high currents (the core permeability becomes unity when saturated). Below article will solve this puzzle of yours. Voltage regulation is needed when operating from an unregulated supply. Typical FR4 PCB material is only rated to 130°C; a power resistor that is traditionally against the board could cause damage to the material during power excursions or reduces the upper temperature performance limits of the circuit. DET 2/3 has a test frequency range of 10 Hz to 200 Hz in steps of 0.5 Hz, with an automatic frequency selection feature that allows users to ensure tests are carried out at the frequency with the lowest noise level. However, there are numerous drawbacks that can limit their use, including non-linear temperature drift requiring compensation, limited bandwidth, low range current detection requires a large offset voltage that can lead to error, susceptibility to external magnetic fields, and high cost. Temperature compensation is also easily integrated. These products do not have as wide of a resistance offering as the Thick Film products, because the resistor alloy has limited resistivities to reach high range values, as well as needing the mechanical strength to tolerate process handling. Another advantage of the Thick Film products is the flexibility to request standard resistance values because of the process efficiency of laser trimming. The new model of the ground tester has a large internal memory that allows quick calculation of resistivity and storage of more than a day’s worth of test results. You have entered an incorrect email address! This low-level output requires an amplifier with low noise, high input impedance and moderate gain. The advantage of Hall effect devices is that they are capable of measuring large currents with low power dissipation. Normally these resistors are assembled in a bridge configuration to compensate for thermal drift. Current sensing is used to perform two essential circuit functions. Fluxgate sensors or Saturable inductor current sensors work on the same measurement principle as Hall-effect-based current sensors: the magnetic field created by the primary current to be measured is detected by a specific sensing element. As the current flows from, Learn how and when to remove this template message, https://en.wikipedia.org/w/index.php?title=Current_sensing&oldid=979492132, Articles needing additional references from October 2016, All articles needing additional references, Creative Commons Attribution-ShareAlike License. In higher current applications; a 30 amp current would provide a 30 mV signal for a 1 mΩ resistance value. Write CSS OR LESS and hit save. The Rogowski coil is similar to a current transformer in that a voltage is induced into a secondary coil that is proportional to the current flow through an isolated conductor. Save my name, email, and website in this browser for the next time I comment. Rogowski coil is based on the principle of Faraday’s law of induction and the output voltage Vout of the Rogowski coil is determined by integrating the current Ic to be measured. The direct method means that it is connected directly in the circuit being measured and that the measurement components are exposed to the line voltage, whereas the indirect method provides isolation that may be necessary for design safety. A magneto-resistor (MR) is a two terminal device which changes its resistance parabolically with applied magnetic field. [7] Thank you, Link is Successfully Activated to save the Book/Material (PDF). The measurement of current ranges from picoamps to tens of thousands of amperes. This potential is proportional to the magnitude of the current flow. The thermal images shown in Fig. The Hall element is the basic magnetic field sensor. They are activated by an external magnetic field. Foil technology has a larger cross section still and is a uniform resistive alloy, which is different from the Thick Film technology that employs resistive materials suspended in a glass matrix. This construction reduces the stress generated by differences in thermal expansion coefficients between the heat producing metal and the dissipating circuit board material. Generally, this method provides a signal with approximately 10% to 20% accuracy. Power quality analyzers are sophisticated tools capable of a wide range of power measurements. Hall Effect current sensors can measure AC, DC, or pulsating current. [PDF] Estimation of Work Hardening in Bent Sheet Metal Products at... [PDF] Concrete Construction Engineering Handbook By Edward G. Nawy Free Download, [PDF] Charging Cost Optimization of Plug-in Hybrid Electric Vehicles. DET2/3 features a graphic display for better data analysis, error detection capabilities, as well as a wide range of test frequencies to ensure noise protection. Because of this high TCR, the temperature must be monitored and compensated to provide an acceptable current measurement. Depending on the transistor product, the accuracy tolerance range can vary from as low as 5% or as wide as 15% - 20%. Power Management, Chapter 3: Power Supplies-Make or Buy. These temperatures are based on reaching thermal equilibrium, however in the application these results may be extended to be considered as the thermal performance characteristics for an overcurrent protection condition. WISHING EVERY PERSON WHO GETS THIS MATERIAL FROM OUR. It is essential to choose the appropriate technology with the necessary robustness to properly withstand the extreme conditions that can exist during a fault. In electrical engineering, current sensing is any one of several techniques used to measure electric current. Measurement of high d.c. voltages as in low voltage measurements, is generally accomplished by extension of meter range with a large series resistance. [PDF] EE6801 Electric Energy Generation, Utilization and Conservation Lecture Notes, Books,... [PDF] Introduction to Mechatronics and Measurement Systems By David Alciatore Free... [PDF] Electrical and Electronics Engineering (EEE) 1st Semester Question Bank Collection... [PDF] New Aspects of Quantity Surveying Practice By Duncan Cartlidge Free... [PDF] Numerical Optimization By Jorge Nocedal and Stephen Wright Free Download. CTRL + SPACE for auto-complete. The pad layout (Fig. Notify me of follow-up comments by email. These structures can be used as magnetic sensors. The reason is the electronic devices divert your attention and also cause strains while reading eBooks. unipolar, with a unipolar output, which duplicates the wave shape of the sensed current, digital output, which switches when the sensed current exceeds a certain threshold. The book is intended not only for experts but also for students in electrical engineering and high-voltage engineering. The common and simple approach to current sensing is the use of a shunt resistor. Two of the three cores are used to create saturable inductor, and the third core is used to create a high frequency transformer effect. The signal conditioning electronics needed are an amplifier stage and temperature compensation. The current sensing MOSFET shown in Fig. For these reasons, current sensing techniques based on physical principles that provide intrinsic electrical isolation deliver a better performance at lower costs in applications where isolation is required. The net current in the meter is usually limited to one to ten microamperes for full-scale deflection. This Book provides an clear examples on each and every topics covered in the contents of the book to provide an every user those who are read to develop their knowledge.

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