Recent content by zub

www.programma.se is another option...

excuse my english first, you have CHL=7180 pF, CL=24950 pF, CH=6550 pF. The equivalent circuit after closing the HV Earthing disconnector is; An inductance (Transformer HV winding) is earthed from the both ends. (Charged the amount of CH when it was energised) And the discharge current will...

you must consider the HV capacitance only. The HV-LV capacitance will still remain and it becomes a LV to ground capacity parallel to LV capacity when you close the earthing disconnector on HV. And it can be neglectible. Hope it helps. zub.

Thank you all for your responses. in my situation there is neither AC nor DC drive. it is a slipring asynchronous 6,3 kV, 2,5 MW. motor and some indications on the bearings. in my understanding this bearing current situation looks like the eddy current! is that right or am i totally wrong. (i...

i am not sure but agree with you. i think it is not neccessary to protect the network trf.'s against overf luxing. For the networks if it happens there are tons of protections on the generation plants for V/Hz. But maybe the experts can show us the right way. regards, zub.

Dear Busbar, I'm actually keeping in search but i couldn't find a right source. i have found two papers on the situation. (One from ABB, one from SIEMENS) But they are global overview on the subject. I want to find something on the theoretical part. Most probably you have better resources...

Hello everybody, What is shaft and bearing current? How does it occure? What are the indications? How can you measure? is there any thread about this topic before? Thanks in advance. zub.

Hi, What is your explanation for this paradox? (at least for me!) 1. The insulation resistance decreases if the heat is increased. 2. The current carrying capacity decreases if the heat is increased. (it means the conductivity decreases so the resistance increases...) it seems a paradox...

Thank you all. it is quite clear now. zub.

Hi all, Everyone knows the current carrying capacity of the busbars increases if the busbar is painted. WHY? it looks simple but i couldn't find any reasonable solution. Can you help me please? zub.

Who knows something about "recurrent surge osciloscope measurement method" will be done on the rotor of synch. generator?. Would you like to share your knowledge with me? thanks. zub.

sorry but i have to add a voltage relay connected to the PT of course.... sorry. zub.

if you are asking how to detect the open circuit during the normal conditions i don't know. But you can detect it when a ground fault occure by using a voltage transformer which connected parallel to the resistor. I'm sure you know this type of application but I wanted to say my opinion. zub.

Hi, Correction: I mean the voltage rising between phase-neutral voltage to phase-phase voltage when a EF occures. regards. zub.

Hello all, We have 4 generators star point grounded through the PT, 8 MVA each. Step up transformers 11/34,5 kV; 8 MVA; Delta-Wye; connected. These four groups paralleled on 34,5 kV bus and one synchronizing breaker connect the bus to the network. The question is we have just one neutral...