How to mitigate Harmonics

We have 750 KVA generator in our Press.Last week this generator malfunctioned. Meanwhile we arranged a generator of 1200 KVA. Press
operates perfectly on 1200 KVA gen. and Power utility comapny. it might be because of harmonics generated from DC Drives in Main panel of Press. We measured harmonics at load side. When load is connected to generator (750KVA), 8.5% THD observed. Magnitude of 3rd harmonic is 8.2%. When load is connected to main Distribution sytem (Power Utility company), THD bacame 2.3% with 3rd harmonic 0.108 % and 5th harmonic 2.077%. My questions are: 1. why press operates perfectly at 1200 kva Genset and Main Distribution system ? 2. why 3rd harmonic is more when load is connected to 750 KVA gen. 3. is the problem laid in genset? 4. How to mitigate the harmonics
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1) I am not sure what your first question is. The press operates because it is getting the necessary violtage.
2) The harmonics are produced by the load. The smaller generator has higher impedance and presents a less stiff source compared to the utility supply, so the generator voltage is affected more by the harmonic load current.
3) I am not sure what problem you are asking about. Someone would need to look at the 750kVA generator to determine if it is good or bad.
4) Bigger generator, harmonic filters, etc. You need a consultant to come in and look at things, then recommend mitigation. You have not provided enough information about the load... kVA rating, type of devices, vfds?, etc.
Ben Miller
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