KEB Combivert F5 series Instruction Manual

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KEB Combivert F5 series Instruction Manual Manual pdf 33 page image

333.2 Input FiltersThe KEBCO line choke reduces the harmonics of the input current and thedisplacement power factor of the inverter improves from 0.5... 0.6 to approxi-mately 0.8... 0.9.Conducted high frequency interference is reduced up to 30 db in the frequencyrange from 10 kHz to approximately 300 kHz.In addition, the noise immunity of the system is improved and the lifetime of theDC-bus capacitors increases.3.2.1 Line ChokeAccessoriesInterference and or voltage spikes on the supply voltage are created when largeloads such as heaters, motors, arc-welders etc. are turned on and off. In someinstances, switching in and out large power factor correction capacitors either inthe factory or on the utility grid can also lead to large voltage spikes appearingat the inverter. These spikes are typically short in time duration but high enoughin voltage to create nuisance tripping of the inverter (i.e. over voltage). Thevoltage spike enters the inverter and raises the DC bus voltage level above thepredefined limit, 400V in 230V units and 800V in 460V units. The protectioncircuits in the inverter activate leading to an interruption in the operation of theunit. The choke prevents these spikes from reaching the inverter eliminating theproblem. 3% impedance chokes are generally sufficient. However 5% will helpfurther reduce harmonic current on the line and will allow the system to bettercomply with the IEEE519 standard.When installing larger inverters (100 hp and greater), harmonic distortion in theline current can become a problem. This distortion is caused by the diode bridgerectifier which serves as the input to all inverters. This distortion can create largefluctuations in the line voltage within a facility leading to problems with otherequipment. The choke reduces the distortion of the current, there by eliminatingthe associated problems.Line Chokes - Additional Information # Connection of the line choke1 Supply fuse2 Disconnect switch or contactor3 Line choke4 Interference suppression filter5 KEB COMBIVERT F56 Sub panel in control cabinet