An improved diagnostic system to detect inter-turns short circuits in low voltage stator windings

2015 ◽  
Author(s):  
L. Frosini ◽  
M. Magnaghi ◽  
A. Albini
Keyword(s):  
Low Voltage ◽  
Diagnostic System ◽  
Stator Windings ◽  
Short Circuits

scholarly journals Regularities of Control of Mechanized Pulse-Arc Welding Process for Ensuring its Stability

2019 ◽  
pp. 65-76
Author(s):  
S. Yu. Maksymov ◽  
L. S. Shlapak ◽  
А. А. Havryliuk ◽  
І. М. Semianyk ◽  
V. А. Onyskiv
Keyword(s):  
Arc Welding ◽  
Low Voltage ◽  
Short Circuit ◽  
Welding Current ◽  
Short Circuit Current ◽  
Average Frequency ◽  
Maximum Value ◽  
Current Growth ◽  
Short Circuits ◽  
Electrode Metal

Mechanized arc welding in protective gases with short circuits (s.c.) is performed at moderate values of the welding current (up to 180 ... 220 A) and at the relatively low voltage (18 ... 24 V) on the arc. The main disadvantage of the process is spattering when melting an electrode metal and when transferring it to a weld bath. The elimination of disadvantages is possible through the implementation of a controlled transfer of molten electrode metal to a welding bath - due to the pulsed nature of arc burning.  At pulse-arc welding (PAW), one of the main methods of increasing the efficiency of the process is to limit the maximum value of the short-circuit current Imax s.c. by increasing the inductive resistance L in the arc-welding circuit. Proceeding from the features of mechanized arc welding, the purpose of the research is to specify the influence of the velocity of the growth of the welding current vс during the s.c. on the arc stability. The implementation of experimental work presupposes surfacing on a plate with the programming of the operating mode of the inverter at different values (9, 12, 15, 18, 21, 24, 27, 30) with the frequency f = 25 Hz and a pulse ratio C = 2. While analyzing oscillograms of welding current and processing their records, it was established that a decrease of the velocity of the welding current growth leads to a significant limitation of the maximum value of the short-circuit current. The statistical processing of the momentary values of the welding current shows that the increase in the velocity of current growth vс starting with vс = 1.23 kA / s to vс = 50 kA / s makes the average short-circuit duration 10 times shorter. At the same time, the average frequency of short circuits grows more than twice. The increase of vс leads to the destabilization of the pulse process and this is reflected in the 30-times increase of the average frequency of arc break. The increase of the energy indexes of the PAW to the Iav. = 220 ... 225 A, Uav. = 24.5 ... 25.9 V, Q ≈ 7.9 ... 8.0 kJ / cm led to the changes in the parameters which characterize the process of pulsed welding with short circuits. There is a sharp decrease in the average frequency of short circuits (2 ... 3 times as rarely) and the average duration of s.c. (twice shorter).

Frequency Characteristics of Generator Stator Windings

2013 ◽  
pp. 151-183
Author(s):  
Charles Su
Keyword(s):  
Pulse Propagation ◽  
Low Voltage ◽  
Travelling Wave ◽  
Wave Mode ◽  
Frequency Characteristics ◽  
Capacitive Coupling ◽  
Stator Winding ◽  
Stator Windings ◽  
Steel Core ◽  
Generator Stator

A generator stator winding consists of a number of stator bars and overhang connections. Due to the complicated winding structure and the steel core, the attenuation and distortion of a pulse transmitted through the winding are complicated, and frequency-dependent. In this chapter, pulse propagation through stator windings is explained through the analysis of different winding models, and using experimental data from several generators. A low voltage impulse method and digital analysis techniques to determine the frequency characteristics of the winding are described. The frequency characteristics of generator stator windings are discussed in some detail. The concepts of the travelling wave mode and capacitive coupling mode propagations along stator winding, useful in insulation design, transient voltage analysis, and partial discharge location are also discussed. The analysis presented in this chapter could be applied to other rotating machines such as high voltage motors.

scholarly journals The Short-Circuit Protections in Hybrid Systems with Low-Power Synchronous Generators

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 160
Author(s):  
Bartosz Rozegnał ◽  
Paweł Albrechtowicz ◽  
Dominik Mamcarz ◽  
Natalia Radwan-Pragłowska ◽  
Artur Cebula
Keyword(s):  
Single Phase ◽  
Low Voltage ◽  
Short Circuit ◽  
Circuit Breaker ◽  
Synchronous Generator ◽  
Synchronous Generators ◽  
Electrical Systems ◽  
Protection Devices ◽  
Short Circuits ◽  
Damage Type

Single-phase short-circuits are most often faults in electrical systems. The analysis of this damage type is taken for backup power supply systems, from small power synchronous generators. For these hybrid installations, there is a need for standard protection devices, such as fuses or miniature circuit breaker (MCB) analysis. Experimental research mentioned that a typical protective apparatus in low-voltage installations, working correctly during supplying from the grid, does not guarantee fast off-switching, while short-circuits occur during supplication from the backup generator set. The analysis of single-phase short-circuits is executed both for current waveform character (including sub-transient and transient states) and the carried energy, to show the problems with the fuses and MCB usage, to protect circuits in installations fed in a hybrid way (from the grid and synchronous generator set).

Detection and location of interturn short circuits in the stator windings of operating motors

1994 ◽  
Vol 9 (4) ◽  
pp. 652-658 ◽  
Author(s):  
J. Penman ◽  
H.G. Sedding ◽  
B.A. Lloyd ◽  
W.T. Fink
Keyword(s):  
Stator Windings ◽  
Short Circuits

scholarly journals FREQUENCY CHARACTERISTICS OF ELECTRICAL MACHINES WITH A MESH WINDING DURING HEAT-AND-MOISTURE AGING

2021 ◽  
pp. 59-66
Author(s):  
V. Chumak ◽  
O. Timoshuk ◽  
Е. Monakhov ◽  
А. Vishnevsky ◽  
А. Stulishenko
Keyword(s):  
Electric Motor ◽  
Low Voltage ◽  
Short Circuit ◽  
Area Under The Curve ◽  
Electric Circuit ◽  
Frequency Characteristics ◽  
Diagnostic Features ◽  
Stator Windings ◽  
Steel Core ◽  
Periodic Monitoring

Operation of an electric drive with damages in power electric circuit of the motor stator results in asymmetry of the motor phase current charge, increase of heating losses in certain phases, occurrence of variable components of electromagnetic torque and consumed power. An electric motor stator winding consists of a number of stator bars and overhang connections. Due to the complicated winding structure and the steel core, the attenuation and distortion of a pulse transmitted through the winding are complicated, and frequency-dependent. A low voltage impulse method and digital analysis techniques to determine the frequency characteristics of the winding are described. The frequency characteristics of electric motor stator windings are discussed in some detail. The analysis presented in this chapter could be applied to other rotating machines such as low voltage motors. An experiment of damping of electric motor wilding was conducted. Changes in frequency characteristics after the cycle are shown. In this article an analysis of the frequency characteristics of low-voltage electric machines with mush-wound windings, taking into account the processes of successive destruction of the insulation structure by the influence of heat-wet cycles. It is shown that the frequency characteristics can be generalized by the parameter of the state of isolation in the conditions of periodic monitoring of the quality of insulation during regulatory audits. It is proved that the frequency characteristics taken in idle and short-circuit modes have diagnostic features of the level of insulation destruction during humidification, which consist of shifting the characteristics of extremes into the region of lower frequencies, as well as reducing the area under the curve between the minimum and maximum extrema of the characteristic.

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