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Goals and Symptoms
I need information about dissipation (power loss) for line choke VZ1L530U045T. Do you have any data about harmonic level during start/stop sequence with and without line choke. When we use line choke with ATS, and have line and bypass contactor (connected to ATS !), is it possible to bypass line choke at END OF RAMP (then it will be used just during start/stop sequence), or it must be connected during whole motor run time? Other way of question: how to install line choke: 1. after line contactor and supply of bypass contactor - outgoing side of choke connected to ATS, or 2. between circuitbreaker and line contactor? Customer wants to implement variant 1. Is it recommendable? System will be implemented on ship, 440V, 60Hz, with generator 1140kW, 1460A. Motor is 285kW, 443A. Softstarter will be ATS48C59Y, and will not be disconnected after starting sequence.
Facts and Changes
ATS and line choke
Causes and Fixes
Line inductance are recommended if there are a few ATS on a same supply to avoid mutual perturbations due to voltage harmonics.
Also It may limit the transient overvoltage if the supply is perturbed.
ATS48 generates significant current harmonics uniquely during the starting and stopping phase, in steady state (when the thyristors are full conducting) they are negligible THD<2% and null with the starter is bypassed.
The harmonics level is difficult to calculate accuratly because it's depending on the impedance of the all installation and it varies with the motor load (power factor is not constant).
The following value are average for a general case:
The maximum values are
Row 5 : 20% of fundamental
Row 7 : 14% of fundamental
Row 11 : 9% of fundamental
Row 13 : 6.7% of fundamental
Other rows are negligible.
Row 3 : less than 10% can appears with a low power factor (no load or at bigenning of starting).
Power loss for VZ1L530U045T = 531 Watts
You can use line choke during start/stop sequence and bypassed after that, connect between the ATS and the line contactor just after the wiring for bypass line ( ie in the user's manual put the choke in place of rapid fuses )