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  1. HamidEle

    Largest LV Motor On VFD

    Thanks for all for the valuable inputs. I did a rough cost analysis and came up with a infection point where any motor larger than 600hp. MV option is more costly. Again, this was based on our layout. It could varies between projects, Suggest to do your check based on your project. Thanks again.
  2. HamidEle

    Largest LV Motor On VFD

    Thanks for your inputs. I think I lean more towards to Gr8blu's thought and stick with IEEE 841 limits for LV Motors, which is 500hp. In terms of harmonic, they can build LV VFD similar to MV VFDs to handle the harmonic issue.
  3. HamidEle

    Largest LV Motor On VFD

    Would like to start the discussion on selection of motor voltages. The IEEE 841 standardizes the use of the LV motor for 500hp and below. Say the motor on VFD, the upstream is a breaker as protection. we could go to a much larger size than 500hp as per the conversation with a motor...
  4. HamidEle

    Synchronous generator field tests

    we are planning for the field test for our on-site generators prior to arranging for the vendor to perform the start-up tests. On top of IR Tests we normally carry out, I have the following tests in my mind for the field acceptance tests, which are part of NETA recommendations: • Stator and...
  5. HamidEle

    460V Motor failed on DC Hi-Pot test

    Great discussions. Thanks everyone again for the invaluable inputs.
  6. HamidEle

    PI Test and Dielectric Absorbtion test on motors

    My bad. I misunderstood the terms. There are definitions in NETA standard. Dielectric absorption is used for 200hp and less. PI is used for larger than 200hp. but not sure if PI test is overkilled for LV Motors.
  7. HamidEle

    PI Test and Dielectric Absorbtion test on motors

    planning to test on motors for our facility. wonder what would be a cost-effective plant for testing motors. Other than IR test, should we consider PI test and Dielectric absorbtion test on larger motors particularly? Say PI on MV motors, and Dielectric AB on LV motors larger than 200hp?
  8. HamidEle

    460V Motor failed on DC Hi-Pot test

    FYI, the vendor came back and recommended to use 500v to Meggaer 460v motor as it is not dielectric withstand test.
  9. HamidEle

    460V Motor failed on DC Hi-Pot test

    Hi, Waross, Initially they tested them on 100V DC and then 500v. it shows some leakage on 500V test. I know NETA allows to Meggar motors under 1000V below using 500v dc. Thanks
  10. HamidEle

    460V Motor failed on DC Hi-Pot test

    Guys, I know most of you are motor experts. Just want to clarify: DC Hi-pot tests on motors are based on phase to ground/earth. For instance, if I use 500v on phase to ground, the phase to phase would be 866V. I just need to Megger the insulation impedance in the field, trying to put stress on...
  11. HamidEle

    460V Motor failed on DC Hi-Pot test

    Thank you guys for the valuable inputs. Just noticed the motor is on VFD and has to withstand at least 1000V reflected wave from the drive output. in this case, we may have to stick with 1000v dc. Otherwise, we would have a problem when running.
  12. HamidEle

    460V Motor failed on DC Hi-Pot test

    Waross and Che, Thanks for your inputs. What Waross sated is correct. Yes. I am in Canada. We carried out the test with Line to earth on 1000V DC. The reading is for Ph-G.
  13. HamidEle

    460V Motor failed on DC Hi-Pot test

    Raghunath, Planning to do a megger test on 500V DC to see what the IRs are. what I am thinking is the motor insulations might be compromised due to the moisture or dirty conditions. will share with you guys later.
  14. HamidEle

    460V Motor failed on DC Hi-Pot test

    Edison123, Thanks for the response. The injected 675V where they failed the test in one minute. The voltage did not even go to 1000v DC. We did not megger it after the failure. Maybe there was a cracking failure which causes the injected to the ground. will find out.
  15. HamidEle

    460V Motor failed on DC Hi-Pot test

    thread237-8885 we failed on some 460V Hi-pot test applying 1000V DC. To me 1000v is a proper DC voltage for 460V motor as per IEEE-43 table-1. Wondering what your thoughts are. Thanks in advance.
  16. HamidEle

    Avctive Filters to choose

    Noticed that some of the active filter will act as added impedances in the system while others do not. TCI does. Acuusine does not
  17. HamidEle

    Avctive Filters to choose

    Thanks!, Jreaf, I had similar experience with Accusine in the past. Started working with TCI. Glad to hear good feedbacks about them.
  18. HamidEle

    Avctive Filters to choose

    We are in the process of selecting active filters for a 480V system. Wonder which ones have the longest history and credits. Thanks in advance.
  19. HamidEle

    Small DG and EPS connection

    Hi, Waross, There are no large spinning motors that quickly. Generators are not redundant and they are expected to run in parallel.
  20. HamidEle

    Small DG and EPS connection

    Here it is, Waross. The PCC is at 115KV. it is a single bus bar substation without main incoming breaker. https://files.engineering.com/getfile.aspx?folder=0ae05c5c-0d9e-4ec0-9581-44476864f56a&file=SLD.pdf

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