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.
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.
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...
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...
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.
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?
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
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...
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.
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.
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.
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.
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.
