An Experimental Insulation Testing Investigation of 210 MW Generator

2018 ◽  
Vol 7 (4) ◽  
pp. 68-91
Author(s):  
Mahendar Kumar ◽  
Z.A. Memon ◽  
M.A. Uqaili ◽  
Mazhar H. Baloch
Keyword(s):  
Short Circuit ◽  
Load Test ◽  
Stable Operation ◽  
Stator Winding ◽  
Insulation Resistance ◽  
Stator Windings ◽  
Rehabilitation Work ◽  
Short Circuit Test ◽  
Winding Insulation ◽  
Potential Test

This article describes how a drastic failure of a machine is caused by insulation collapse which results heavy interruption as well as losses. The stable operation of a generator mainly depends upon the stator winding insulation. In past, various testing and repairing techniques have been applied in order to analyze the insulation life. However, in this context, a complete stator windings insulation analysis have been carried out by testing and monitoring techniques such as insulation resistance, di-electric absorption ratio, polarization index before repair and after rehabilitation work, ac & dc high voltage, dc resistance test of winding coils, as well as surface potential test, no-load test and short circuit test. It basically reflected the insulation life of stator winding and helped to take remedial measures. This research techniques will pave the way to overcome such failure in machine and recommended the interval based tests for safety purpose.

Design, Construction and Performance Evaluation of a Low Cost Electric Arc Welding Machine

2009 ◽  
Vol 62-64 ◽  
pp. 135-140
Author(s):  
S.O. Igbinovia ◽  
M.C. Onuoha ◽  
O.K. Olaogun
Keyword(s):  
Arc Welding ◽  
Low Cost ◽  
Short Circuit ◽  
Electric Arc ◽  
Load Test ◽  
Welding Machine ◽  
Short Circuit Test ◽  
Operating Current ◽  
Electric Arc Welding ◽  
And Performance

Apart from woodwork, brickwork, all other formworks are of metalwork. Thus engineering devices, equipment, machineries and infrastructures are made possible with the use of welding machines, be it carbide or arc – welding type. In Nigeria, where the cost of imported goods rises astronomically in accordance with the foreign exchange rates, the need to fabricate this very important equipment became of important necessity. In this paper, a single-phase 6KVA, 240VAC/30-70 VDC electric arc welding machine was designed and constructed using locally available materials. The different operating current required, arcing time, the heat generated by the arc, the minimum arc gap, the fluxite coated electrode, oxidation of the molten materials by the surrounding air where some of the designed parameters that determined the auto-transformer specific magnetic loading and specific electric loading. Cooling medium, integral switch, the rectifier circuits and the tanking of the transformer designed determined the equipment production. The locally fabricated AC/DC air cooled electric arc welding machine capable of withstanding 200A, when subjected to insulation resistance test, no – load test, short circuit test and on-load test to ascertain its performance characteristics were very satisfactory.

scholarly journals Grid-like Vibration Measurements on Power Transformer Tank during Open-Circuit and Short-Circuit Tests

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 492
Author(s):  
Karlo Petrović ◽  
Antonio Petošić ◽  
Tomislav Župan
Keyword(s):  
Power Transformer ◽  
Short Circuit ◽  
Frequency Component ◽  
Open Circuit ◽  
Load Test ◽  
Mode Shapes ◽  
Vibration Velocity ◽  
Tank Wall ◽  
Vibration Measurements ◽  
Short Circuit Test

In this work, the vibrations on the surfaces of the tank wall, stiffeners, and the cover of a 5 MVA transformer experimental model were measured during open-circuit and short-circuit transformer tests. Vibration measurements of a transformer tank side were conducted at discrete points using two different voltage sources in no-load test. Using interpolation functions, the RMS values of acceleration and vibration velocity are visualized and compared for each considered measurement configuration (no-load and load tests and two different excitation sources). Significant differences in mode shapes and amplitudes of vibrations at different frequencies are observed. The maximum RMS values of acceleration, velocity and displacement in the open-circuit test are 0.36 m/s2, 0.31 mm/s, and 0.42 µm, respectively. The maximum values in short-circuit test are 0.74 m/s2, 1.14 mm/s, and 1.8 µm, respectively. In the short-circuit test, the frequency component of 100 Hz is dominant. In the open-circuit test, the first few 100 Hz harmonics are significant (100 Hz, 200 Hz, and 300 Hz). In addition to the visualization of RMS values during the open-circuit and short-circuit tests, animations of the vibrations are created. Fourier analysis and phase comparison between frequency components are also used to show vibration animations at dominant frequencies in the spectrum (100 Hz harmonics). The visualization of the vibrations at the tank wall surfaces is transferred into 3D space in such a way that all 15 surfaces are mapped to the spatial coordinates of the surfaces so that a 3D model of the acceleration, vibration velocity, and displacement of the transformer tank is shown.

Diagnostics of Stator Winding Faults in a Three-Phase Asynchronous Motor Using Park’s Vector Analysis

Vestnik MEI ◽  
2021 ◽  
pp. 69-74
Author(s):  
Muhammad Deeb ◽  
◽  
Gassan Ibragim ◽  
Talal Assaf ◽  
◽  
...  
Keyword(s):  
Induction Motor ◽  
Short Circuit ◽  
Asynchronous Motor ◽  
Vector Model ◽  
Stator Winding ◽  
Stator Windings ◽  
Stator Current ◽  
Experimental Part ◽  
Three Phase ◽  
Short Circuit Fault

The study addresses the problem of detecting a short circuit fault in the three-phase induction motor winding by monitoring the stator current Park vector (Lissajous curves). Park's vector model is implemented using the Matlab software package. The experimental part of the study was carried out on an 11 kW three-phase induction motor. The Lissajous curves obtained for a healthy motor and a motor with short-circuited turns under various load conditions were compared with each other. The obtained results have demonstrated the effectiveness of the proposed method for detecting interturn short circuit faults in the three-phase stator windings of induction motors.

scholarly journals Determining an additional diagnostic parameter for improving the accuracy of assessment of the condition of stator windings in an induction motor

2021 ◽  
Vol 5 (5 (113)) ◽  
pp. 21-29
Author(s):  
Oleg Gubarevych ◽  
Sergey Goolak ◽  
Olena Daki ◽  
Yuriy Yakusevych
Keyword(s):  
Induction Motor ◽  
Induction Motors ◽  
Short Circuit ◽  
Rotation Frequency ◽  
Additional Parameter ◽  
Stator Winding ◽  
Diagnostic Parameter ◽  
Stator Windings ◽  
Shaft Rotation ◽  
Additional Diagnostic Parameter

This paper has proposed and substantiated the application of an additional diagnostic parameter for assessing the state of stator windings of induction motors during operation. The dependences of the values of phase shifts between phase currents and phase voltages have been obtained. These dependences showed that when an inter-turn short circuit occurs in the stator windings, the phase shifts are the same for all phases of the motor. That has made it possible to obtain the dependence of the change in phase shift on the change in the engine shaft rotation frequency. This study's result has established the dependence of the rates of change of the phase angle on the engine shaft rotation frequency for both one and two damaged phases with varying degrees of damage. When analyzing these dependences, it was found that with an increase in the number of damaged phases of the electric motor, the linear section of the dependences decreases. In addition, with an increase in the degree of phase damage, the angle of inclination of the linear sections of the characteristics decreases. That has made it possible to determine an additional parameter for diagnosing the place and degree of an inter-turn short circuit of the windings in an induction motor with a squirrel-cage rotor. The values of the additional parameter, termed by this paper's authors as a "phase criterion" can be used to assess the condition and degree of damage to the stator winding of induction motors. The values of the phase criteria for various types of damage were: when phase A is damaged by 90 %, ξ=0.634, (deg)2/(rpm)2; when phase A is damaged by 80 %, ξ=0.393, (deg)2/(rpm)2; when phase A is damaged by 80 % and phase B is damaged by 90 %, ξ=0.25, (deg)2/(rpm)2; when phase A is damaged by 80 % and phase B is damaged by 90 %, ξ=0.173, (deg)2/(rpm)2. The results of this research could be used to select an effective method for diagnosing an inter-turn short circuit in the stator winding when building a diagnostic system for induction motors as part of drives of transport equipment

scholarly journals Development of the software-hardware complex for diagnostics of inter-turn short circuits of stator windings of asynchronous motors

2021 ◽  
Vol 288 ◽  
pp. 01040
Author(s):  
Roman Dolgih ◽  
Ivan Suvorov ◽  
George Palkin ◽  
Sergey Kakaurov ◽  
Marina Morozova
Keyword(s):  
Short Circuit ◽  
Asynchronous Motor ◽  
Research Work ◽  
Technical Condition ◽  
Diagnostic Methods ◽  
Operating Voltage ◽  
Stator Winding ◽  
Stator Windings ◽  
Hardware Complex ◽  
Short Circuits

Up to 38% of asynchronous motor (AM) failures are caused by damage to the stator insulation. Despite the wide variety of methods, the reliability of determining the inter-turn short circuits of stator windings under operating voltage still remains at a low level. The existing methods for diagnostics of asynchronous motor failure of the interturn short circuit of stator winding have been examined. New diagnostic methods for individual parameters developed in the course of the previous study are described. A new diagnostic method is formulated, on the basis of which the research work is carried out. The method will allow us to constantly monitor the technical condition of the stator winding, and identify its damage at an early stage of their development. Diagnostics can be performed without dismantling the engine and without removing it from the working process. The microprocessor unit is implemented for diagnostics of the technical condition of AM introducing this method. Moreover, the software and hardware complex is implemented for diagnostics of the technical condition for AM. The results of experiments on a laboratory stand with inter-turn AM closures are presented, which confirm the higher reliability of monitoring.

Invasive Methods to Diagnose Stator Winding and Bearing Defects of an Induction Motors

2019 ◽  
pp. 122-130
Author(s):  
Muhammad Aman Sheikh ◽  
Nordin B. Saad ◽  
Nursyarizal Mohd Nor ◽  
Sheikh Tahir Bakhsh ◽  
Muhammad Irfan
Keyword(s):  
Induction Motor ◽  
Condition Monitoring ◽  
Failure Modes ◽  
Short Circuit ◽  
Raw Material ◽  
Maintenance Cost ◽  
Stator Winding ◽  
Stator Windings ◽  
Bearing Defects ◽  
Bearing Failures

Condition monitoring in an induction motor must concentrate on the root causes of the failure modes that exhibit a slow failure sequence. According to published surveys, two-fifths of the faults are due to bearing failures. Inter-turn short circuit faults in stator windings are approximately responsible for one-third of the motor faults. In the last few decades, various methods and alternative techniques have been proposed and implemented to diagnose induction motor faults. In an induction motor, stator winding and bearing faults account the largest percentage of motor failure. Due to the fact these faults can lead the motor to catastrophic failure that are expensive in term of maintenance cost, wastage raw material, and unplanned shutdown. Thus, to diagnose the state of motor and overcome existing problem, the chapter provides detailed invasive methods which are proposed and are currently in practice. Moreover, the chapter also highlights the limitation, scope, and the challenges of existing invasive condition monitoring techniques.

scholarly journals Experimental simulation analysis for single phase transformer tests

2020 ◽  
Vol 9 (3) ◽  
pp. 862-869
Author(s):  
Ali N. Hamoodi ◽  
Bashar A. Hammad ◽  
Fawaz S. Abdullah
Keyword(s):  
Single Phase ◽  
Simulation Analysis ◽  
Power Transformer ◽  
Short Circuit ◽  
Electrical Power ◽  
Load Test ◽  
Experimental Simulation ◽  
Electrical Power System ◽  
Test Procedures ◽  
Short Circuit Test

Transformer is one of main components in electrical power system which role to increase or reduce voltage. Characteristics of transformer would be vital to ensure the voltage is fully transferred. A single-phase transformer is a type of power transformer that utilizes single-phase alternating current, meaning the transformer relies on a voltage cycle that operates in a unified time  phase. This article describes a workflow executed with Mat lab simulation and practical measurements for single-phase power transformer, no-load, short-circuit test and load test are achieved in this work. The test procedures are implemented on areal transformer (terco-type) which has a specification (1 KVA, 220/110 V, 50 Hz). Finally, the simulation results are appeared a proximately seminar from the practical results. The results indicated that the the technique and manner which presented in the current study can be depended as a miniproject in electrical technology mater for undergraduate studies.

scholarly journals Modified Rotor Flux Estimators for Stator-Fault-Tolerant Vector Controlled Induction Motor Drives

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3232 ◽  
Author(s):  
Mateusz Dybkowski ◽  
Szymon Antoni Bednarz
Keyword(s):  
Induction Motor ◽  
Fault Tolerant ◽  
Short Circuit ◽  
Experimental Tests ◽  
Point Of View ◽  
Stable Operation ◽  
Stator Winding ◽  
Classical State ◽  
Rotor Flux ◽  
Rotor Flux Estimators

This paper deals with fault-tolerant control (FTC) of an induction motor (IM) drive. An inter-turn short circuit (ITSC) of the stator windings was taken into consideration, which is one of the most common internal faults of induction machines. The sensitivity of the classic, well-known voltage and current models to the stator winding faults was analyzed. It has been shown that these classical state variable estimators are sensitive to induction motor parameter changes during stator winding failure, which results in unstable operation of the direct field-oriented control (DFOC) drive. From a safety-critical applications point of view, it is vital to guarantee stable operation of the drive even during faults of the machine. Therefore, a new FTC system has been proposed, which consists of new modified rotor flux estimators, robust to stator winding faults. A detailed description of the proposed system is presented herein, as well as the results of simulation and experimental tests. Simulation analyses were performed using MATLAB/Simulink software. Experimental tests were carried out on the experimental test bench with a dSpace DS1103 card. The proposed solution could be applied as an alternative rotor flux estimation technique for the modern FTC drive.

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