Dear friends,
The answer to my problem was found. The problem of high tandelta lay in the bad quality of insulating material used in the divertor switch of the OLTC.This was detected at the manufacturers works.the manufacturer has agreed to replace all fibreglass supporting and insulating...
Dear scottyUk
Yes I,ll have a look at the busduct image current path.But when the transformer is back energised there is no current in the busduct connected to the generator and also because the Generator circuit breaker between the transformer lv and the generator is OPEN.The arcing is between...
This case is very interesting .Can you paste the single line diagram of the interconnection between the Transformer,motor and generator.Such an unbalance is not normal.It would then be easier to analyse.
DEAR SCOTTYUK,
Iam sorry i donot have a photograph readily for sending it to you.This transformer is fitted with a typical oil impregnated paper bushing(on the 220kV side).The busduct is a pressurised air isolated phase busduct on the lv side while the 220kV side is connected to the 220kV yard...
In India any motor capacity upto 200kW is preferred to be run on 3-phase 0.415kV ,beyond which it is techno economic to run on 3.3/6.6/11kV.If you insist to run on 0.415kV,for capacities greater than 200kW,other options like dual drives can be thought of.Again it is a matter of choice depending...
The bushings are the OIP type and were tested at 10kV.the tandelta values were less than 0.5.I am not unaware about the differences between tandelta and power factor as i understand that at low angle delta, tan delta equals cosine(90-delta)and 90-delta is the angle phi.Hence cosine phi...
dear fellow members,
what could be the reasons for arcing across the transformer top cover flange whenever the transformer is back charged from the 220kV side.This is a Generator step up unit connected to a Gas turbine Generator thro a GCB.During start ups the auxiliary board is energised thro...
Thank you dandel and oldfieldguy for your valuable comments. Let me assure you that the tests were repeated a number of times considering the suggestions you have pointed out.However do you think that a strip down of the transformer at manufacturers premises could reveal problems with...
As per my understanding tandelta(power factor) tests for Transformer windings are not included in the IEC or BS. Should these be included for acceptance of a new transformer?
What values of tandelta for CH,CHL,CL can be acceptable?
In one of our 200MVA single phase 21/400 kV Generator step up...
