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Bernatt J.,Branzowy Osrodek Badawczo Rozwojowy Maszyn Elektrycznych KOMEL
Przeglad Elektrotechniczny | Year: 2010

High voltage (6000 and 10000 V) AC squirrel cage motors are started by switching direct on line. The inrush of starting current causes mechanical and thermal stresses in the motor structure, mainly in their rotor's cage. Motors for hard working conditions, esp. for high frequency of starts, or for long lasting starts should be designed and manufactured especially. At Komel Centre several calculation and designing methods for motors exploited at hard working and starting conditions were elaborated. The motors were exploited several years in various branches of industry without any breakdowns. In the paper three cause studies are presented: 550, 800, and 2000 kW motors, where redesigning and replacing only their rotors were full satisfactory.


Glinka T.,Silesian University of Technology | Glinka M.,Branzowy Osrodek Badawczo Rozwojowy Maszyn Elektrycznych KOMEL
Przeglad Elektrotechniczny | Year: 2012

Design of steel-plant furnace three-phase transformer (110 kV/(350 to 500) V, 50 kA) and its operating conditions are described in the paper. After three months of operation this transformer failed. Cause of failure, its course and damage to transformer winding are presented. Recommendations for transformer winding design and its installation and protection are given.


Bernatt M.,Branzowy Osrodek Badawczo Rozwojowy Maszyn Elektrycznych KOMEL | Rut R.,Rzeszow University of Technology | Mroz J.,Rzeszow University of Technology
Przeglad Elektrotechniczny | Year: 2012

Industrial AC cage rotor motors of nominal voltage 6000 and 10 000V are usually started by switching direct on line (d.o.l.). Many failures of the motors is often the result of the thermal and mechanical stresses caused by initial starting current surges in stator and rotor (squirrel cage) windings, as well as electro-dynamic vibrations occurred at starting period. In the paper thermal and dynamic effects of starting current of d.o.l. started motors are evaluated, same examples of typical disintegrated squirrel cages showed and recommendations for motor's exploitation given.


Dukalski P.,Branzowy Osrodek Badawczo Rozwojowy Maszyn Elektrycznych KOMEL | Bialas A.,Branzowy Osrodek Badawczo Rozwojowy Maszyn Elektrycznych KOMEL | Radwanski W.,Branzowy Osrodek Badawczo Rozwojowy Maszyn Elektrycznych KOMEL | Bedkowski B.,Branzowy Osrodek Badawczo Rozwojowy Maszyn Elektrycznych KOMEL | Frechowicz A.,Silesian University of Technology
Przeglad Elektrotechniczny | Year: 2013

Traction calculations of the car with BLDC motor with switchable number of turns with a permanent magnets electric motor with a capacity of 70kW are presented in the paper. The calculations of ability to overcome the motion resistance of the car and capable of speeds and accelartions at different ratios are shown. The necessary improvements to mount the electric drive and good points of this solution are discussed. The project of the drive is realized by Silesian University of Technology and Research and Development Centre of Electrical Machines KOMEL.


Bernatt J.,Branzowy Osrodek Badawczo Rozwojowy Maszyn Elektrycznych KOMEL | Bernatt M.,Branzowy Osrodek Badawczo Rozwojowy Maszyn Elektrycznych KOMEL
Przeglad Elektrotechniczny | Year: 2013

High capacity induction squirrel cage motors used at different industrial drives are usually started by direct line starts. Starting current, several times higher than nominal load current, causes thermal and mechanical dynamic stresses posing hazard to motor construction. Both stator and rotor windings are endangered at starting period, but stresses in rotor cages are usually considerably higher, therefore rotor design (and its manufacturing process) is of high importance for motor's durability.

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