• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.48 no.3
• /
• pp.192-199
• /
• 1999

During start up and shut down, the generator is rotating at a low speed and copper dusts cause arcing between the turns in the slot. Shorted turns occurred primarily by the movement of these copper dusts between individual windings in the generator rotor. Detection of shorted turns was performed in five gas turbine generators in two combined cycle power plants. Two types of permanent and temporary flux probes were used in this paper. These flux probes have been used to develop a methodology for detecting shorted turns in an operating generator's rotor. The flux probes sense the rotor winding slot leakage flux and produce a voltage proportional to the rate of change of the flux. This pattern of flux variation is the signature unique to each rotor winding. An appropriate waveform analysis technique canidentify the pole location, the slot number, and the number of shorted turns within each slot. Shorted turns in field winding of gas turbine generator(125.7 MVA) were detected to twelve turns on al total 190 turns.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.8
• /
• pp.1555-1559
• /
• 2011

Turbine generator(13.8 kV, 137.5 MW) has high bearing vibration at rotation speed. Shorted turns in generator rotor windings have strong correlation with increased field current which is thus related to increase in bearing vibration. The recurrent surge oscillograph (RSO) test is performed on the rotor winding in turbine generator to detect shorted turns. The result of the RSO test indicates that shorted turns of rotor winding are generated in two locations. The RSO test was capable of identifying the presence, number, and location of shorted turns in generator rotor windings.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.10
• /
• pp.1818-1821
• /
• 2008

Several off-line diagnostic tests which include the insulation resistance(IR), polarization index(PI), low-voltage AC, and recurrent surge oscillograph(RSO) tests were performed to assess the condition of generator rotor windings. The low-voltage AC and the RSO tests were performed on the gas turbine generator rotor winding to detect shorted turns. Before intentionally applying artificial shorted faults, it was confirmed by the low voltage AC and the RSO tests that the winding was in sound condition. For simulated shorted rotor winding turns, the RSO test detected the fault in the winding. The RSO test was capable of identifying the number and pole location of the shorted turns for a number of simulated shorted coils.

• Proceedings of the KIPE Conference
• /
• 2003.07a
• /
• pp.137-140
• /
• 2003

Shorted-turns can have significant effects on a generator and its performance. Shorted-turn sensor for synchronous generator's field winding have been developed. One of effective method detecting inter-turn short circuits on round rotor winding is a method using sensor detecting. But the method needs duplicate design of sensor for characteristic change according to types and forms of generator Thus sensing skill without sensor depend on change of electric property in generator. For the reason, this paper presents shorted-turns phenomenon and the characteristic analysis of shorted-turns In synchronous generator by using 2-D finite element method(FEM).

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.48 no.11
• /
• pp.742-747
• /
• 1999

On-line diagnosis system has been developed and is now applied the detection of shorted turns in the field winding of large generator. This system consists of data aquisition system and display PC. The data aquisition system detects voltage waveforms from flux probe sensor installed in the stator slot. The display PC shows theshorted-turn situation of generator rotor winding. A shorted-turn diagnosis test wasperformed on five gas turbine generators at the Seoinchon combined cycle power plant. The test was conducted using an new diagnosis system and digital oscilloscope which can identify the pole location, the slot number and the number of shorted turns within each slot. It is confirmed that results of two systems are very same in the field tests.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.11 no.6
• /
• pp.570-576
• /
• 2006

This paper describes a method for the detection of shorted-turn in the cylindrical synchronous generator rotor windings based on the discrete wavelet transform. Multi-resolution analysis(MRA) based on discrete wavelet transform provides a set of decomposed signals in independent frequency bands, which contain independent dynamic information due to the orthogonality of wavelet function. In the proposed method, shorted-turn detection in rotor windings is based on the decomposition of the rotor currents, where wavelet coefficients of these signals have been extracted. Comparing these extracted coefficients is used for diagnosing the healthy machine from faulty machine. Experimental results are presented for healthy, and machines with 25%, 42%, 67%, 83%, 99% inter-turn short circuits in a rotor slot. Deviation of wavelet coefficients in healthy mode from faulty modes depicts the inverse proportion of shorted-turns. Experimental results show the effectiveness of the proposed method for shorted-turn detection in the cylindrical synchronous generator rotor windings.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.10
• /
• pp.1882-1888
• /
• 2010

It is widely known that ESA(Electric Signature Analysis) method is very useful one for fault diagnosis of an induction motor. Online fault diagnosis system of induction motors using LabVIEW is proposed to detect the fault of broken rotor bars and shorted turns in stator. This system is not model-based system of induction motor but LabVIEW-based fault diagnosis system using FFT spectrum of stator current in faulty motor without estimating of motor parameters. FFT of stator current in faulty induction motor is measured and compared with various reference fault data in data base to diagnose the fault. This paper is focused on to predict and diagnose of the health state of induction motors in steady state. Also, it can be given to motor operator and maintenance team in order to enhance an availability and maintainability of induction motors. Experimental results are demonstrated that the proposed system is very useful to diagnose the fault and to implement the predictive maintenance of induction motors.

• Proceedings of the KIEE Conference
• /
• 1998.07e
• /
• pp.1721-1724
• /
• 1998

A shorted-turn test was performed at the Pyungtaek combined cycle power plant on gas. turbine generator #4. The test was conducted using a permanent flux probe and digital oscilloscope. The flux probe installed in the generator air gap, senses the field winding slot leakage flux and produces a voltage proportional to the rate of change of the flux. This pattern of flux variation is a signature unique to each field winding. We have also applied a waveform analysis technique that can identify the pole location, slot number, and number of shorted-Turns with each slot.

• Proceedings of the KIEE Conference
• /
• 2005.10c
• /
• pp.35-37
• /
• 2005

Large generators are subject to high mechanical and electrical stress which may lead to deterioration of the insulation. The rotors, in particular, may develop short circuits particularly and there is a need for the operators to be aware of this situation. In this paper, the electromagnetic characteristics of the generator with shorted turns in rotor field winging is analyzed by FEM and the detection algorithm method of the shorted turn rotor slot position is proposed.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.10 no.3
• /
• pp.257-263
• /
• 2005

Short-circuit rotor windings on a generator causes unstable oscillation of unbalance of flux, asymmetrical heat. In order to prevent serious accidents of short-circuit rotor windings, it is important to study the shorted-turn diagnosis method for rotor windings of the generator. To improve the defects of the diagnosis with sensors, the new sensorless method for rotor shorted-turn diagnosis is proposed, which is to measure the electrical values of the voltage and current at the generator and then to detect if the shorted-turned phenomena would occurred. For the feasibility of the suggested method the theoretical results are shown in the aspects of the air-gap flux density, the flux leakage, the generated output voltage and the shorted field current through the digital simulation. Also the possibility of decision for the suggested sensorless method could be shown in this paper.