Witsarut Sriratana

Application of Hall Effect sensor: A study on the influences of sensor placement

In this study, the influences of the position and direction of Hall Effect sensor and permanent magnet were assessed to evaluate the appropriate placement of the sensor module under the same conditions. The experiment was divided into 4 cases: Single Hall Effect sensor, 5-Array Hall Effect sensors, 4-Array Hall Effect sensors, and 4-Crossing Hall Effect sensors. Moreover, the density of magnetic field from permanent magnet was varied by 135 mT, 292 mT, and 281 mT and magnetic poles were alternated in each experimental case. In case of the sensor module with 4 Hall Effect sensors, the number of magnetic poles was equal to the number of sensors. Output signal from experiment was in electrical analog form and then transmitted to a computer for collecting in the database and analyzing the accuracy of the sensor module via 12-bit and real time ADC processed by ARM7 Microcontroller.

Design of Capacitive Sensor for Concentration Measurement

This paper presents the analysis of ideal equivalent circuit of the developed concentration sensor probe for chemical solutions by regarding to reasonable costs and reliability of device. The designed sensor probe consists of 2 parallel electrode plates that are coated by Nylon with 0.4 mm thick and mounted together by Resin with 2.5 mm of gap (0.09 times greater than electrode width). Any capacity changes will be compared with the electric circuit that is obtained from the Good Will R-L-C standard instrument, model CTR, at the frequency extending from 100 Hz to 2 kHz. From the experiments, it was found that the sensor designed for ethyl alcohol solution within concentration of 5% to 95% and 10% concentration interval, at room temperature of 23 degC and frequency of 100 Hz, can provide the results with high linearity as well as high resolution of capacity change which is 2 pF per 1% of concentration

Subsidence monitoring system for industrial machines based on magnetic field method

This study presents the design of subsidence monitoring system for industrial machine alignment based on magnetic field method. The system was developed to demonstrate the level of land subsidence in the area of the industrial machine located. A computer was used to collect the data and to display the angles of subsidence over operation period. The measurement module consists of two thin-and-curve permanent magnets (10 mm × 41.5 mm × 1.5 mm) with the outer radius of 24 mm, the curve angle of 120 degree, and the maximum magnetic density of 0.23 Tesla. The gap between these two magnets was 12 mm to generate the magnetic tension force. The sensing module was Hall Generator placed perpendicularly to the magnetic fluxes which can generate the output voltage as a function of subsidence angle and magnetic density on X axis and Z (vertical) axis with the resolution of 100 mV per degree. There were two ranges of measurement according to the angle resolution: -20 to 20 degree at 1 degree of resolution per step and -6 to 6 degree at 0.05 degree of resolution per step.

Pipe inspection system using a polarized transverse wave EMAT

The conventional non-destructive inspection of a pipe by an ultrasonic wave has low inspection efficiency because it is a technique that uses a longitudinal wave or transverse wave which propagates in the thickness direction of a pipe with a smaller area than the size of the ultrasonic sensor. However, a guide wave is provided with the characteristic of long range propagation in the axis direction of a pipe, so it is possible to detect many defects over a large pipe area at once. At present, there is a technique to generate a guide wave using a piezoelectric element (PZT). Such a transducer has some difficulties in industrial applications, which requires a high viscosity couplant. Therefore, we tried to develop a guide wave inspection system that uses an electromagnetic ultrasonic transducer (EMAT) which does not require any couplant. First, we confirmed that a guide wave can be transmitted and received in an aluminum pipe by a polarized shear horizontal transverse wave-EMAT, and we have confirmed the most suitable transmission and reception EMAT’s specification and the most suitable drive conditions to generate the L, T and F-mode guide waves. Finally, the detection performance has been evaluated by the developed system.

Application of parallel ladder technique for purging oil residual inside the copper pipe

In iron pipe industry, one of the most important problems in manufacturing processes is the great amount of oil residual in copper pipe. This problem can be affected the use of copper pipe further such as difficulty in pipe soldering, pipe rust and leakage. This study aims to demonstrate the use of parallel ladder technique, the simple process with low additional costs, to purge out liquid residual in the pipe after ironing. This technique can improve the efficiency of the manufacturing process as well as increase the quality of the product. Nitrogen was applied in this process with the step-increasing pressure of 0, 5, 10, and 15 Bar. This supplied pressure levels are a function of time which depend on the length of pipe. Nitrogen with specified pressure levels were controlled by 3 sets of control valves which were parallelly arranged. For efficiency test, two sizes of copper pipe which are commonly used for producing coil of air conditioner were used as a case study, Pipe A (diameter of 7.29 mm, thickness of 0.25 mm, length of 10 km) and Pipe B (diameter of 8 mm, thickness of 0.25 mm, length of 10 km). From experiments, the parallel ladder technique can eventually reduce the liquid residual inside the pipe. For Pipe A, the residual was reduced from 1.468 mg to 0.045 mg or 3.65 %. For Pipe B, the residual was reduced from 1.916 mg to 0.054 mg or 7.29%. The average oil residual purged out from Pipe A and Pipe B were 1.42 mg or 96.35%, and 1.86 mg or 92.71%, respectively. It can also be indicated that water and oil residual in the pipe were significantly less than the standard limitation (0.1 mg/m or 30%).

An experimental study of natural lighting for energy conservation using top-up control method

This paper presents the experiment-based analysis of interior illuminance from natural lighting through clear glazed window of a reference room located in Bangkok, Thailand, during February to May 2007 as a case study. The point illuminances measured by photoconductive sensors were collected every 5 minutes and the average interior illuminance from natural lighting were then calculated instantaneously. In this study, natural lighting also aims to reduce the requirement of electric lighting during daytime (7 am-5 pm) of the reference room. If natural lighting alone cannot supply the light at the required value, the electric lighting is assumed to be switched on under top-up control method to maintain the standard illuminance level. The average interior illuminance, which comprises of natural light and electric light, is controlled to be stable at the IES standard level of 500 lux. Nine sets of high performance lamp, 56 lm/W of efficacy, are assumed to supply the light to meet the standard condition. The requirements of supplementary lighting and possible savings during the test months are finally estimated.

Experimental Study on Differentiating between Natural Honey and Honey Glucose Syrup by Using Hall Effect Sensor

This study presents the application of Hall Effect sensor for differentiating the combination of liquids based on electrical conductance. Electromagnetic field was generated from wire (AWG 31) bound on high frequency magnetic core namely Toroidal iron power (T131-26) or C-shape Toroidal core. In this study, the electrochemical cell was fixed at 0.09375 cm-1 and there were 10 samples of several liquid types for testing. Hall Effect sensor was designed to place with high frequency magnetic cores bound by 310-turns wire. From experiment using electromagnetic field generated by C-shape Toroidal core, it can be observed that the samples of natural honey from Germany (J) and sugar substitute for diabetics (I) could be distinguished by considering output voltage of Hall Effect sensor (VH) and electrical conductance. The output voltage and the electrical conductance from measurement of natural honey (J) were 3.037 V and 0.941 mS.T, respectively while those from measurement of sugar substitute (I) were 3.030 V and 0.938 mS.T, respectively. Moreover, it can be noted that this methodology could be applied for measuring electrical conductance of several liquid types due to the relationships of output voltage of Hall Effect sensor and electrical conductance of liquid. However, only C-shape Toroidal core was used in this study due to the appropriate generation of electromagnetic field for differentiating both sample liquid types with 1.83% of error for natural honey and 1.51% of error for sugar substitute from 195 times of repetitive measurement.

Analysis of liquids conductivity using hall effect sensor based on electromagnetic field properties

This paper presents a new methodology of analyzing liquid conductivity via the Hall Effect sensor based on electrochemical properties. Two different magnetic field cores with the same coil length (10 m, AWG 31) were studied, namely ferrite solenoid cores and toroidal iron powder cores (T131-26). The magnetic field generated by both type of cores was then used to generate a Hall voltage with the cores ratios of 1 : 1. The output Hall voltage is, in turn, sent through a microcontroller, together with a 10 bit converter for real time data analysis. The magnetic-field density of the solenoid for analyzing the conductivity of brine is 31 mT for solenoid, and 10.74 mT for toroid cores, respectively. Results from other materials are compared to the reference conductivity values of salt solution, which amounts to 16.211 mS/cm when assessed with the solenoid core, and 16.406 mS/cm when assessed with the toroid core.

Measurement of metal particles in oil lubricant using hall effect sensor under temperature conditions

This paper develops a Hall-Effect sensor based system to assess the performance of a lubricant. The measurement methodology is based on the fact that the electromagnetically induced voltage is directly proportional to the amount of contaminants, which in turn affects the state of the lubricant. Two main cases are considered: the metal particles contaminant, and viscosity. The sample lubricant viscosity was experimentally found to be 49.2874 Cst, which is well within the range of internationally accepted values. Furthermore, the lubricant flow rate was also found to be temperature dependent. The output Hall voltage for the contaminated lubricant was 0.8 A for liquid flow rates between 0 to 30 l/h, which significantly deviates from the non-contaminated lubricant. These results suggests that the presented approach is a simple, low cost system capable of accurately assessing the performance of lubricants without consulting the manufacturers information, even under normal operational loading.

Error Analysis of 4-Crossing Hall Sensor with Frequency Domain in Measurement of Material Imperfection

This study presents a methodology of frequency domain for analysis the output signal of the sensor device in order to enhancing the performance and resolution in measurement of a sensor module. However, in this case used the new sensor module namely 4-crossing Hall sensor, which was designed by the assembling of four permanent magnets with four Hall generators as a sensor device. An analysis of frequency domain in this study aims to develop a new non-destructive measurement using a new sensor module as a sensor device in order to measure the imperfection of metal materials using, in some cases, the methodology of non-destructive inspection. This process was performed by transforming the values in the pattern of the output voltage from sensor device, which was amplified by the instrumentation amplifier into the time domain by the voltage to frequency converter and then transformed into the frequency domain based on the principle of Fourier transform. It was found that an analysis by frequency domain is the methodology which can be explicitly applied to detect the dimension of holes on a metal surface. In an experiment, the principle of frequency domain can precisely determine and distinguish the depth of drilled holes with 1 mm difference.