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    The Low Voltage Isolation Transformer Failure Investigation: Measurements, Analysis and Lessons Learned
    (2020-09-01)
    Boonseng, Chongrag
    ;
    Boonseng, Rapeepornpat
    ;
    Kularbphettong, Kunyanuth
    This paper presents a case study of failure analysis for a 200kVA, 400 V isolation transformer at a semiconductor plant with a start-up with problems faced before permanent damage. The basic requirements of the acceleration of the dynamic transformer to achieve a successful start will be checked In addition, the results of the measurement of the location of the electrical parameters and the separation process are shown to indicate the cause of the error and evidence of the testimony. The results are confirmed by a failure analysis report provided by the manufacturer. This paper also addresses the obstacles that are faced due to the limited error and availability of information and how to solve the problem.
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    Diagnosis of Oscillation and Vibration of Dry-Type Transformers Caused by Harmonic Resonance
    (2020-09-01)
    Boonseng, Chongrag
    ;
    Boonseng, Rapeepornpat
    ;
    Kularbphettong, Kunyanuth
    This paper has investigated the oscillation and vibration of dry-type transformers under harmonic current and resonance system. Power dry-type transformers are the equipment being critical for the availability of electrical energy networks. Prevention of failures gains importance considering outage time and resulting subsequent costs. Therefore, permanent monitoring of dry-type transformer is used. The inspection begins with turning off the electric load of the heater, resulting in a completely silent sound and no vibration. The analysis results from the data can show that resonance occurs in electrical systems at frequencies in the range of 100, 150 and 1,150 Hz. Modifying and controlling the harmonic level by installing a Hybrid Power Filter System (HPFs) which uses the Passive Power Filter System (PPFs) to filter the harmonic current down first and then using the Active Power Filter System (APFs) eliminates the remaining harmonics in the system. The harmonic filtering operations of PPFs and APFs are independently separated, with the PPFs positioned near the electrical load and the APFs positioned near the transformers. Finally, the harmonic current can be reduced to a very good level of about 3%. As a result, the dry-type transformers do not make sound, do not oscillation or vibrate.
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    Agricultural Mobile Robot Body Vibration Characterization Using Integral Based Methodology
    (2019-04-01)
    Boksuwan, Sungwan
    ;
    Chesof, Abdulhafiz
    ;
    Wongvanich, Napasool
    ;
    Panaudomsap, Sumit
    This paper presents the application of integral based method for characterization of the vibration in the four-wheel agricultural mobile robot, which is designed for use in applications such trimming, spraying and harvesting. Vibration occurs when one of the wheels does not touch the ground which reduces an effective of end effector. In order to design an effective controller, an accurate mathematical model is needed. Results show that the proposed method can simplify the system identification procedure, while yielding excellent match in comparison to the standard black box method. The proposed algorithm gave an NRMSE match of 96.8%, while the standard method yielded a 76.1% match. This match is also found to be lower when the validation data was from other experiments.
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    Vibration analysis based on magnetic field balancing technique
    (2018-08-13)
    Sriratana, Witsarut
    ;
    Saithong, Pasut
    ;
    Sriratana, Lerdlekha
    This paper presents the design of a vibration measurement system according to ISO 10816-1 standard. In this study, a vibration measuring device was applied the magnetic field balancing technique. For study, the vibration generated for experiment was from a vibration of the motor which taking load in various conditions. The operation and performance analysis of the motor in terms of balance and unbalance position of load can be determined by dividing the experiment into four conditions: Balance position, 25% of unbalance position, 50% of unbalance position and 75% of unbalance position. The magnetic field method influenced by the permanent magnets was applied and the Hall Effect sensor was used as a sensor. The results of the experiment were then compared to those from output voltage of the Hall Effect sensor as well as those from the magnetic field density for analysis the vibration and the effectiveness of motor. The results of the experiment can be considered in terms of torque, frequency and the output voltage of Hall Effect sensor. It was found that the output voltage of Hall Effect sensor at balance position, 25% of unbalance position, 50% of unbalance position and 75% of unbalance position were equal to 2.54 V, 2.67 V, 2.77 V and 2.86 V, respectively while the average of process error was 0.34%.