Thanks for the reply. I have seen the motor today at the workshop. Rubbing is severe. They are recommending DC Hi Pot at 10.5 KV ( 80 % of 2 x rated voltage + 1).
Can you eloborate the rotor core loss? I will discuss the possibility with them.
We have opened the motor at site and found severe rotor/stator rubbing. It is amazing as before running the motor we have moved it by hand as a test of free movement of rotor and it did not take extra force. One electrician moved it. No abnormal noise was observed with stethoscope.
Now it...
I am not enrolled in an online program. I am rather doing a part time M.Sc. degree from university campus. I have to attend at least 2 classes a week from 4 to 6 pm.
Motor winding heater was kept on 24 hours before starting till the winding temperatures became 3 C higher than ambient.
Bearing Oil level is still OK. It is at the mid level as recommended by manufacturer.
We have opened the side covers. No signs of burning are there. Winding resistances have...
Last month, we got our 1000 HP 6.6 KV motor cleaned after 6 years of operation. When the motor was run, it gave whitish smoke. Motor was stopped immediately (it ran for appr. less than a min). Megger results were showing the motor to be OK.
We called the service guys who have cleaned the motor...
Thanks guys. You finally got it right. I was looking for the answers to the review problems. I needed it coz of academic purposes.
To tell you the truth, i have my B.E. in electronics and i am working in power field for the last 6 years or so at a power plant. Couple of months of back i...
TTR was carried out after the operation of diff relay. The most disrubing thing to me is the HV side in excess of rated FLC. Yes, the LV current you calculated is ok.
I am collecting a sample for DGA. But it will take time before i get the results of the analysis.
Tap changer is on HV side...
Recently, on our 12.5 MVA, 15.5 / 6.9 KV Dyn1 transformer, differential relay operated while changing the taps.
The transformer has 17 taps position i.e., +8, .., 0, ..., -8 with a regulation of 10 % voltage.
The incident happened when the operator was changing the tap from -7 to -8 position...
