Protect motors with more efficient energy use
Drives with variable rotation speed are now a fixed component of machines and plant. As well as basic fundamental properties such as controlling motor speed and resulting movements, frequency converters substantially reduce the start-up current peaks and energy consumption. This is supported by KEB's EMC sine filters.
Stopping climate change and generally reducing CO2 emissions are important goals in society. Drive electronics with ultra-modern semiconductors for high switching frequencies and reduced switching losses are important elements in optimising the energy use in processes and operations. But this also has a disadvantage: rapid switching of intermediate circuit voltage leads to increased dV/dt’s from pulse width modulation. These are generating extra load on the motor windings from the discharge of high voltages between two adjacent windings, which can lead to premature damage, in particular with long motor cables
In larger motors, high dV/dt values also lead to bearing damage. An electrical field is generated between the stator and the rotor which, when attempting to discharge itself, creates small sparks between the bearing cage and the balls or rollers. These discharges damage the lubricant film in the bearing, and premature failure is the certain result.
To avoid such damage, KEB has developed a new range of EMC sine filters. From the switched PWM voltage, a sinusoidal voltage is recreated on the motor cables and the motor is thus protected. The range comprises a total of seven physical sizes in the application range from 9 to 460A.
The advantages of using the EMC sine filters:
- Motors can be used together with driver controllers without special isolation systems or isolated bearings. This applies to ASM, PM and IPM motors.
- Increased efficiency of the motor, since sinusoidal phase voltages and currents mean lower losses in the stator and rotor.
- Almost unlimited motor cable length, as sinusoidal voltages and currents are generated between phase and ground: particularly useful in submersible pumps or with motors operated in parallel on a converter.
- Cost reduction from the use of unshielded motor cables.
- Parallel connection of converter and filter allows systems for usage ranges up to 710 kW or 1330 A.
- Maximum output frequency up to 100 Hertz.
- CE and UL certification supports global use.
Tested areas of application include textile machinery with multi-motor operation, pumps and fans with long cable lengths, operation of old motors with frequency converters in the chemical and oil industry, and luggage sorting systems with open induction linear motors. The sine wave EMC filters secure long-term operation in crane systems with trailing cable feed to motors, on test benches for electric motors, and in network simulation (artificial mains) systems.