• Journal of Electrical Engineering and Technology
• /
• v.10 no.3
• /
• pp.1086-1092
• /
• 2015

The off-line and on-line partial discharge (PD) in the stator winding of three high-voltage (HV) motors (1,400 HP, 6.6 kV) is measured and analyzed in this paper. The off-line PD is measured at high values between 24,300 ~ 36,100 pC after 18 years of motor operation. Spare replacement motors were not available for testing the degree of deterioration of the stator windings in standstill status. Therefore, on-line periodic analysis was conducted to monitor the trend of PD after installing a ceramic sensor (110 pF, 6.6 kV) in the terminal box for each phase of each motor. In the stator winding of the No.1 and No.2 HV motors, which showed high magnitudes of off-line PD and low magnitudes of on-line PD, defects are expected to appear in the neutral end of the winding. On the contrary, in the stator windings of the No.3 HV motor, which exhibits high off-line and on-line PD magnitude, defects are expected to appear in the terminal end of the winding where a voltage close to the phase voltage is applied.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.3
• /
• pp.125-131
• /
• 2007

Electric motor efficient improvement from home appliance field is important to the effect reducing the energy consumption. But the electric motor design/analysis technology is still insufficient. Specially the electric motor design/analysis technology of satisfying characteristic of both the induction motor and the synchronous motor such as Line start permanent motor. Therefore the electric motor design/analysis technology is urgently demanded reliability. This paper proposes the sing1e-phase line-start permanent magnet motor to develop the motor it with be able to alternate the sing-phase induction motor it is a refrigerator compressor motor. The sing-phase induction motor is analyzed in the steady state. And we have a certification test to compare our single-phase line-start permanent magnet motor with the sing-phase induction motor. In order to improve the performance, the stator of the single-phase line-start permanent magnet motor is same as the stator of the sing-phase induction motor and changes the rotor form and has the permanent magnet. It used the Finite Element Method(FEM) which is widely used with electronic-magnetic field numerical analysis method.

• Journal of Korean Medicine Rehabilitation
• /
• v.28 no.1
• /
• pp.85-96
• /
• 2018

Objectives This study was performed to compare the electrical methods of motor points mapping using surface EMG and electric probe (Pointer Excel II). Methods 32 healthy adults (male 16, female 16) were selected. and classified into two groups; surface EMG group, electric probe (Pointer Excel II) group. In surface EMG group, motor points were searched by recoding the compound muscle potentials. In electric probe (Pointer Excel II) group, motor points were searched by scanning the skin with Pointer Excel II at low level stimulation. The locations of the motor points were expressed as X and Y values in relation to the reference line. The horizontal reference line was set as elbow crease and the vertical reference line was set as the line connecting coracoid process to the center of the horizontal reference line. The data was analyzed by 'Independent T-test' and 'equivalence test'. Results 1. The motor points of short head and long head of biceps brachii muscle were located at about 2/3 length of the vertical reference line from coracoid process and about 1/5~1/4 length of the half of the horizontal reference line from the vertical reference line in both group. 2. The motor points of the short head were located more distally and close to the vertical reference line (p<0.001). 3. In surface EMG group, the motor points of the long head were located more laterally in the female than male. And the motor points of the long head were located more distally in the left side than right side (p<0.05). In electric probe (Pointer Excel II) group, similar tendency was observed but there was no statistically significant difference (p>0.05). 4. As a result of the equivalence test between surface EMG group and electric probe (Pointer Excel II) group, the confidence intervals of the difference were within the equivalence limit. Therefore, the locations of the motor points searched by two ways are equa l (p>0.05, equivalence interval=3%). Conclusions The results indicate that electric probe (Pointer Excel II) can be used to search the motor points instead of surface EMG. This might improve the clinical efficiency when using the motor points to treat muscle dysfunction.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.52 no.2
• /
• pp.53-60
• /
• 2003

This paper deals with steady-state analysis of a single-phase line-start permanent magnet synchronous motor. In order to analyze the steady-state characteristics, the asymmetric single-phase line-start synchronous motor is converted to the symmetric two-phase synchronous motor, that is, the asymmetric magnetic field is separated from the positive and the negative symmetric components using symmetrical-component theory. The analysis method of the synchronous motor on the d-q axis coordinates is used for the positive component and the equivalent circuit of the induction motor is applied for the negative component analysis. Moreover, d-q axis inductance considering current phase angle is applied to positive component analysis for precise characteristic analysis. In order to validate the proposed analysis method, the analysis results are compared with the experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.28 no.1
• /
• pp.29-35
• /
• 2014

The purpose of this paper is the rotor design of a single-phase LSPM(Line-start permanent magnet) motor. A single-phase LSPM motor has a permanent magnet in the rotor that is same as induction motor. For that reason, magnet is operated by breaking torque in starting region and alignment torque in driving region. Therefore, we need the design process considering the trade-off relationship. In this paper, we propose the design process of a single-phase LSPM motor for a high starting torque and efficiency with FEM. And we use Taguchi Method for considering tolerance in manufacture. Finally, we compared the LSPM motor that is designed in this paper and conventional induction motor.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.8
• /
• pp.1390-1396
• /
• 2007

The line-start permanent magnet synchronous motor has a high efficiency and an advantage in constant speed operation regardless of the effect of load variation. However, it is difficult to predict the performance of characteristics accurately, because of the unbalanced starting torque with the initial starting position of the rotor and the generation of a break torque. In this paper the dynamic characteristics of the line-start permanent magnet synchronous motor are described and compared with those of the squirrel-cage induction motor through the simulation to find the characteristics of the permanent magnets and the rotor bars in the line-start permanent magnet synchronous motor. Finally this paper gives the comparison between the simulation results and the experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.52 no.6
• /
• pp.262-270
• /
• 2003

In this paper, the characteristics of single-phase line-start permanent magnet synchronous motor driven by constant voltage are analyzed on d-q axis vector diagram and compared with that of current controlled motor. The coupled method of symmetrical coordinates and d-q axis voltage equation are applied to the analysis method like the analysis of single-phase induction motor. From the result of the analysis, it is seen that motors driven by constant voltage source have effects on not only the amplitude of current and torque but also current and current phase angle, so overall characteristics such as power factor and load angle are affected by circuit parameters. For precise analysis and design of single-phase line-start synchronous motor, its characteristics should be analyzed on d-q axis vector plan in consideration of the variation of circuit parameters.

• Proceedings of the KIEE Conference
• /
• 2006.04b
• /
• pp.185-187
• /
• 2006

The line-start permanent magnet synchronous motor has a high efficiency and an advantage in constant speed operation regardless of the effect of load variation. However it is difficult to predict the performance of characteristics accurately, because of the unbalanced starting torque with the initial starting position of the rotor and the generation of a break torque. In this paper the dynamic characteristics of the line-start permanent magnet synchronous motor are described and compared with those of the squirrel-cage induction motor through the simulation to find the characteristics of the permanent magnets and the rotor bars in the line-start permanent magnet synchronous motor.

• Proceedings of the KIEE Conference
• /
• 2008.04c
• /
• pp.92-94
• /
• 2008

The interest in permanent magnet synchronous motor is present in a wide area of applications, ranging from high-performance servo drive to line-start application[1]. The are mainly two reasons for this trend: first low rotor losses and second the foiling prices of high-energy magnets. In this paper the dynamic characteristic of the line-start permanent magnet synchronous motor are described and compared with those if the squirrel-cage induction motor through the simulation to find the characteristics of the permanent magnets and the rotor bar in the line-start permanent magnet synchronous motor.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.53 no.2
• /
• pp.58-64
• /
• 2004

Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating voltage unbalance. Voltage unbalance is a condition in a polyphase system in which the rms values of the line-to-line voltages or the phase angles between consecutive line-to-line voltages, are not all equal. Slight voltage unbalance generates a disproportionately high current unbalance at the motor stator winding. This paper presents a scheme on operation states of a three-phase induction motor under unbalanced voltages. The three-phase voltages applied to the stator winding of the studied induction motor are controlled by respectively adjusting the magnitude and phase angle of each phase. The voltage unbalanced factor(VUF) of the three-phase source voltages can then be varied to examine the different values of VUF on machine's operation characteristics.