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| Sinamics offers optimum current infeed concepts for every application | | Three for all cases | With three infeed concepts, the Sinamics drive family has the right solution for every application. Infeed of current without mains feedback as the most economical solution for exclusively motorized operation, standard solutions with uncontrolled infeed/feedback unit for occasional generator operation and controlled infeed/feedback unit for particularly high demands on system availability and mains quality.
Most drives are operated exclusively as motors in industrial applications. Typical examples of this are pumps, fans, compressors, extruders, mixers, mills and conveyor technology. Low-cost, space-saving devices of the series Sinamics G120 (modular single drives from 0.37 to 90 kW), Sinamics Basic Line Modules, Sinamics G130 (single drives for powers up to 800 kW), Sinamics G150 (single drive in the standard cabinet) and medium-voltage converters GM150, all with Basic Infeed are the most recommendable. The line-commutated infeed with diode infeed is totally sufficient in these relatively simple applications with square and constant torque curve to achieve the basic advantages of variable speed operation. This includes optimized process control - variable speed systems are more accurate and respond much faster than mechanical controls - and soft start-up and run-out which is kind on both the network and the complete powertrain. There is also an energy saving of up to 50 %, especially in applications with square torque curve such as pumps, fans or compressors. The purchase of such a converter therefore often pays off in a few months. But the Basic Infeed method is also used in Motion Control applications in production machines - as one of three possible infeed concepts of the Sinamics S120 multi-axis drive system.
Systems capable of feedback with IGBT technology
Applications requiring a mains feedback demand solutions which go beyond the Basic Infeed concept. Such applications are, among others, conveyor belts, elevators, paper machines or systems for steel production. Motor and generator drive requirements often come together here. Because the brake energy is transformed into electrical energy in generator operation, infeed concepts capable of feedback are called for in this case. The standard solution is Sinamics drives with Smart Infeed.
Uncontrolled infeed/feedback units in IGBT (Insulated Gate Bipolar Transistor-) technology feed the energy back into the mains. The user therefore saves double: The fed back energy can be used by other consumers and there are no costs for heat dissipation measures which are required for conventional brakes. Sinamics S120 Smart Line modules and Sinamics G120 in the PM250 version are suitable for this. Unlike infeed/feedbacks in thyristor technology in which mains interruptions lead in principle to so-called inverter tripping with fuse dropout and thus to a system fault, the new Sinamics S120 Smart Line modules offer a much greater fail safety due to the IGBT technology which enables active disconnection.
Minimum mains feedback at maximum fail safety
The Active Infeed technology is ideal where the compensation of mains interruptions or very low mains feedbacks are called for in addition to the feedback capability. Controlled infeed/feedback units in IGBT technology (or IGCT technology in Sinamics SM150) supply the connected drives with a constant voltage. A fast vector regulation provides a sinusoidal mains current. This applies both for the energy drawn from and fed back into the mains. In addition, an integrated Clean Power filter almost completely eliminates the pulse frequency mains feedbacks. The values are well below those of conventional 12, 18 or 24-pulse converters. This not only satisfies the strict regulations of many energy supply companies. It also does away with the losses in the low voltage distribution, the mains transformer and the mains supply line due to overshoot currents.
Insensitive to voltage fluctuations and mains interruptions
Maximum fail safety is provided in drives with Active Infeed by the constantly controlled intermediate circuit voltage which decouples the motor from the main voltage. The current converter operates here as an up transformer with an intermediate circuit voltage above the peak value of the mains voltage. This makes the drive system insensitive to mains voltage fluctuations. This guarantees highest precision of the generator even on weak mains. The intermediate circuit voltage controlled to a fixed value bridges brief mains interruptions and the drive system continues to run.
Freely selectable power factor enables reactive power compensation
The power factor cos phi is freely selectable in Active Infeed. No reactive power is taken up in the standard setting cos phi = 1. Different settings offer the possibility of feeding an inductive or capacitive reactive current into the mains within wide limits and to compensate parallel reactive power sources in this way. This reduces the expensive reactive power consumption of the energy supply company and makes the compensation systems commonly found in conventional infeeds superfluous. Typical areas of application of the Active Infeed method are, for example, test benches, hoisting units, printing machines, machine tools and production machines or sugar centrifuges.
Advance 4 / 2006 | |
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