Modernization and performance data upgrading of high power electric motors at their repair process

The paper presents a possibility of improving perf ormance data and durability in exploitation of high power electric motors at their repair process. Some redesigning of the motors may be necessary. Examples of redesigned squirrel cage motor output up to 3200 kW are given. As a result increasing of durability for hard staring conditions (frequent or long lasting starts of the motor), diminishing the noise level or increasing of efficiency level of the redesigned motors were a chieved.W artykule przedstawiono możliwość znaczącej poprawy parametrów technicznych (w tym również trwałości eksploatacyjnej) silników elektrycznych dużej mocy, którą można osiągnąć w trakcie remontu. Do osiągnięcia tego konieczne są jednak pewne zmiany projektowo- konstrukcyjne w remontowanym silniku. Podano przykłady dla silników klatkowych mocy do 3200 k

Electric motors selection for middle and large capacity industrial drives

Selection of electric motors used in various kinds of industrial drives is realized at designing stage of that drives. But the exploitation condition of the machine not always can be properly foreseen at designing stage. And the exploitation condition (especially starting conditions) heavily influence electric motor’s working reliability. For middle and large capacity d.o.l. started induction motors the frequency and duration of their starts is of crucial importance for motor’s reliability. The motors for high frequency of starts and for long starting time (driving equipment of large inertia moment) should be specially designed. Proper design of the rotor cage for this motors is of high importance. Komel Center elaborated own methods and computer programs for designing rotor cages of large induction motors for heaviest starting conditions

Big capacity squirrel cage motors for frequently repeated or long lasting starts

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

Permanent magnets motors - a new solution for electrical drives

The paper deals with permanent magnets motors for traction application. In past years, in locomotives designed for mining applications DC motors of output 25/45 kW were used. Since 1990 such motors have not been manufactured, so the old motors have to be replaced by new ones. Due to usage of PM, designers increased the output of the motors to 33/60 kW. The motors were designed as motors with magnets mounted on the surface of the rotor. A method of field weakening was implemented into electronic converter supplying the motor to increase the rotation speed from 1500 up to 2250 rpm. A number of laboratory test were done. The paper presents results of the tests and shows the area of installation of PM motors. Komel Centre is ready to design and manufacture motors with PM for different application (rail traction, electric cars and vehicles, pumping systems etc)

About possibilities of reducing electrical energy consumption by electrical drives

High output induction motors working in polish industry are the subject of the paper. It is estimated, that only in polish powerplants work more than 2000 motors output higher than 200 kW. Also in brown coal-mines hundreds of high voltage slip-ring motors are installed. The presently exploited motors are mainly out-dated, manufactured and designed more than 20 - 30 years ago. These motors are characterised by low efficiency factor and high noise level. Figure 1 indicates the value of efficiency factor of different type induction squirrel cage motors (domestic and foreign). It can be easily noticed that modern motors have the efficiency factor higher of even 4% than the old ones. The old motors should be replaced by modern, energy efficient ones. The Table 3 and 4 present the possibilities of replacing these old machines by new, modern motors. In case of replacing motors in powerplants with generation units of 200 MW, savings of electricity per 1 drive and for all main drives together are shown. The total energy power savings balance at the level of 500 kW, what for 7000 operating hours per year enables to save about 3400 MWh

Squirrel cage induction motors with idle bars

The paper describes high output induction motors driving large applications of heavy starting conditions. Heavy start is characterised by long accelerating time and occures in drives of hudge inertia torque, esspecially when performed at full load. The reliable operation of the motors depends on proper design and quality of rotor's cage. The aspects of thermal behaviour and electrodynamic forces have to be considered during the design of the motor for hard working conditions. In the paper the rotor with idle bars is investigated