Your transformer has a D winding in low voltage as i see in one of your sketch so i will not expect to feed a ground fault. What are the trafo winding settings in ETAP?
G.F.
www.engineering-services.gr
Don't you need anyway an insulation coordination study for the dimensioning of the arrester, taking in mind all possible cases like system symmetrical or asymmetrical faults, switching over voltages, energizing of lines ,load rejections etc?
G.F.
www.engineering-services.gr
Thanks ScottyUK for your comment, you are right.I thought we were talking about an MCCB feeding an MCB. For residential applications the opposite is possible but you throw away your money.
G.F.
www.engineering-services.gr
Have a look on those ABB discrimination tables attached. The case of MCB and MCCB is of course posible.
G.F.
www.engineering-services.grhttp://files.engineering.com/getfile.aspx?folder=71a57748-5484-43f1-80b4-1a41a7e0ab81&file=1sdc007004d0206.pdf
For secondary injections i am using Freja and Omicron. I prefer omicron as it has a big and user friendly test template library for almost all protection relays. With such a template you can automatically perform tests and prepare the relevant documentation.
G.F.
www.engineering-services.gr
Have a look in the attached file. It is from the generator i mention in my previous post.
G.F.
www.engineering-services.grhttp://files.engineering.com/getfile.aspx?folder=66452e3f-a74d-4814-b25c-e666f81c6c1b&file=LRCURVE.jpg
For a detail answer on the time needed for stabilization after starting such a motor you have to ask the generator vendor.
From my experience, a 1,2MW four stroke diesel generator running in lets say 10% load can start without any problems or significant voltage dips a 350kW motor. Depending on...
For the step up transformer you have to see what will be the voltage drop across the impedance for the motor start up current. Use as uk=5% as it is typical until 1000kva. A 1000kva transformer has a short circuit aprox. 28kA. Your motor if we assume it has 6 times nominal it will reach during...
If i was you, i would choose the generator trafo to be Δ in generator side in order to trap currents caused be asymmetries (I2) and the third harmonic caused by the non linear B-H characteristic of the transformer core. The other side is preferred to be Y solidly or earthed via impedance (that...
As far as i understand the 11kV network is ungrounded and delta connected (are you in an old cement factory?). The load flow is from the 33kv to 0,4kv and there is no power generation at low voltage side.
If the loads (motors or whatever) are connected in LV side then all the load asymmetries...
What are the transformer kVA and vector groups? What are the fuse ratings? Do you have any disturbance recordings from a protection relay? When you say hv fuses on the transformers you mean the 11kV side of the 11/0,4kV trafos? It seems very interesting.
G.F.
www.engineering-services.gr
A useful article from Kumblar and Kulkarni.
G.F.
www.engineering-services.grhttp://files.engineering.com/getfile.aspx?folder=41a561fc-e4e7-49aa-83db-d2295b23c949&file=Sympathetic_Inrush.pdf
Maybe this is useful,...
G.F.
www.engineering-services.grhttp://files.engineering.com/getfile.aspx?folder=50b6bd4f-6adc-44e8-acc3-8b2f31195a94&file=1SDC007109G0201.pdf
