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An analysis of iron loss supplied by sinusoidal, square wave, bipolar PWM inverter and unipolar PWM inverter
(2007-12-01)
Khluabwannarat, P.
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Thammarat, C.
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Tadsuan, S.
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Bunjongjit, S.
This paper presents a comparison of iron loss with sinusoidal supply (50 Hz) 1-phase square wave inverter supply 1-phase bipolar PWM inverter and 1-phase unipolar PWM inverter. In the experiment, using 0.5 mm.-thick Non-oriented magnetic steel and by setting equal maximum fundamental magnetic density for each test procedure, with 0.3, 0.45, 0.6, 0.9-modulation indexes and 1, 3 kHz. -inverter switching frequencies results show that the iron loss by 1-phase PWM inverter supply is less than other inverters, so this study is useful for selecting the PWM inverter with a lower iron loss. © 2007 RPS.
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Oil-immersed transformer temperature monitoring by ANSI/IEEE C57.91 model
(2007-12-01)
Maleewat, P.
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Tadsuan, S.
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Saelee, V.
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Chompoo-inwai, C.
This article presents the development of a 3-phase oil immersed transformer temperature monitoring equipment. The developing prototype employs ANSI/IEEE C57.91 standard mathematical model to calculate the hottest spot of the transformer winding, and use the AT89CS8252 MCS51 microcontroller for an implementation. Main components of the newly developed prototype consists of input sensors, MCS51 microcontroller, and 7-segment display. Input sensors are RTD (PT100), CT and PT. An output display is 7-segment displaying transformer current, voltage, ambient temperature, top-oil temperature and hot-spot temperature. Test results show that measuring temperatures obtained from the new prototype are close to those from the conventional standard measuring instruments (CSI). As a result, transformer industries can find the benefits of the developing prototype of gathering and analysis transformer temperature data. In addition, this equipment can notify operators if their operating transformers are withstanding the overload or over temperature or not. © 2007 RPS.
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Comparision of power loss of three-phase induction motor of four techniques with PWM inverter supply
(2007-12-01)
Tadsuan, S.
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Suechoey, B.
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Saelee, V.
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Chompoo-Inwai, C.
The purpose of this research is to study the power loss in three-phase induction motors linked with a three-phase PWM inverter by adjusting various fundamental wave voltages of the motors. The experimental procedures used four adjustment techniques as: 1. Constant DC link voltage inverter and adjusting the modulation amplitude 2. Constant modulation amplitude equal 1 and adjusting DC link voltage of inverter 3. Sixstep inverter and 4. Constant modulation amplitude equal 2.3 (over mod land adjusting DC link voltage of inverter. The four techniques were used to adjust V/f-type fundamental waves. The results indicated that the adjustment technique showing the power input, power output, power loss and efficiency of the motor. © 2007 RPS.
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Single phase and three phase PWM inverter supply optimum selection for core losses reduction
(2006-12-01)
Suechoey, B.
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Thammarat, C.
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Tadsuan, S.
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Leelajindakrairerk, M.
This paper presents the comparison of core loss with 1-phase bipolar inverter supply to 3-phase inverter supply (2- line). In the experiment, by using 0.30 mm.-thick grain oriented magnetic steel(M5) and by setting equal maximum magnetic density for each test procedure, with 0.3, 0.6, 0.9- modulation index and 1, 2, 3, 4, 5 kHz.- inverter switching frequency, the voltage and current are saved to data file. By using the function FFT program to analyze the data file, the test results shown that the core loss by 3-phase inverter supply (2-line) is less than that by 1-phase bipolar inverter supply, so this study is useful for selecting the PWM inverter to get the lower core loss.
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Core loss prediction mathematical model design with single phase PWM inverter supply
(2006-12-01)
Suechoey, B.
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Thammarat, C.
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Tadsuan, S.
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Bunjongjit, S.
This paper presents the core loss mathematical model design and the prediction of core loss with PMW Inverter supply. In the procedure, the 1-phase bipolar PWM inverter supply is used to supply the Epstein test apparatus with the 0.23 mm., 0.27 mm., 0.30 mm.-thick sheet, grain oriented magnetic steel, and 0.5 mm.-thick sheet, Non oriented magnetic steel. By setting the equal maximum magnetic density for each test procedure, with 0.3, 0.6, 0.9- modulation index and 1-9 kHz inverter switching frequency, the test results are shown that the core loss by the prediction is nearly the same that by the experiment, with 0.3, 0.6, 0.9- modulation index, so this mathematical model design is more useful and can be applied to the design work in electrical machine equipment.
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An analysis of total loss and temperature of oil-immersed transformer with short circuit test linear load and non-linear load
(2005-01-01)
Suechoey, B.
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Tadsuan, S.
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Khluabwannarat, P.
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Chompoo-inwai, C.
This paper presents the measured temperature at top oil and on winding at high voltage part, low voltage part due to winding loss. By placing the thermocouples at the bottom, the middle and the top of mineral oil-immersed transformer, the variety winding temperatures are measured. The 3 - test conditions are 1. Short circuit test, 2. Linear load test and 3. Non linear load test. The temperature results show the difference temperature at any parts of the 10 kVA, 380V/220V, 3 phase, Dyn11 and ONAN ventilating transformer. The results of measured temperature will be compared with one another to get the difference temperature. If that temperature is higher than the rated temperature of insulator in transformer, its lifetime will be shorter. Finally, the result will be analysed about the relations among heat at any part and are useful for design, correction and protection of the transformer by heat.
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An analysis of temperature and pressure on loading oil-immersed distribution transformer
(2005-01-01)
Suechoey, B.
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Tadsuan, S.
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Thammarat, C.
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Leelajindakrairerk, M.
This paper presents the analysis of temperature and pressure on loading oil-immersed distribution transformer at rated load. The tested transformer is sealed type oil-immersed distribution transformer of 400 kVA 3ph 50Hz 22000-400/230V Dyn 11. The results will be useful for developing the design, correction, protection, load specification and temperature estimation of transformer with efficiency, in order to improve better cooling and transformer tank's strengthen. And these will increase transformer aging and stability of distribution system.
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The result analysis of the power loss 3-phase induction motor with PWM inverter supply
(2005-01-01)
Thammarat, C.
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Tadsuan, S.
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Suechoey, B.
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Bunjongjit, S.
The purpose of this research is to study the power loss generating of the PWM inverter and the 1 HP 380V 3-phase squirrel cage induction motor. In the test procedure was performed by varying fundamental frequency in the range 25-50Hz and at constant 1.5 kHz - PWM Inverter switching frequency, as a source to the 3-phase 380V squirrel cage induction motor in star connection with 5.1 N.m constant torque load. The test analysis was to record the input/output voltage/current waveforms by using YOKOGAWA DL1640 Storage Oscilloscope. Then, using the function FFT program was to determine the variety parameters at each harmonic from those waveforms. The total power loss and efficiency a were calculated by those parameters. The results show the input power is minimum at 25 Hz fundamental frequency and maximum at 50 Hz. But the efficiency is minimum at 25 Hz fundamental frequency and maximum at 50 Hz. The minimum motor power loss is at 35-40Hz fundamental frequency and the maximum inverter power loss at 81-85% efficiency is around 25-50 Hz fundamental frequency. And also, this is the useful information in designed inverter process to extend the motor' life due to the overheat from power loss.
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An analysis of temperature of oil-immersed transformer under non-linear load
(2004-12-01)
Thammarat, C.
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Suechoey, B.
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Tadsuan, S.
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Kinnares, V.
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Bunjongjit, S.
While loading transformer with the non-linear load, the overheating problem will occurr and the insulator winding life will be reduced too. This research presents the oil-immersed transformer temperature test at conductor at high and low voltage side, and temperature test at top oil of oil-immersed transformer. To generate the harmonic current and harmonic voltage, we load the transformer with non-linear load, such as rectifier, heater and capacitor,and record current and voltage data. The results of the testing are calculated and compared with the 2-different methods, the K- factor method and the model method. Finally, the model method temperature is nearly the same as the experimental temperature, so this research is more useful to protect the transformer from overheat. © 2004 IEEE.
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Estimation of core loss of transformer under non-sinusoidal voltage supply
(2004-12-01)
Suechoey, B.
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Tadsuan, S.
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Thammarat, C.
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Leelajindakraireak, M.
This paper presents the 1-phase transformer core loss estimation under non-sinusoidal voltage supply. The Epstein test apparatus, with grain oriented magnetic steel side M5 (0.3mm), inverter and low pass filter is used in estimation of core loss. The calculated results will be compared with the measured value and are useful for the appropriate single phase transformer design under non-sinusoidal voltage supply. © 2004 IEEE.

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