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Thanks a lot for informations. regards, zkz

Hello, Thanks for all who gave me advices. As per your suggestion, we do not have to consider actual ambient temperature(which was 34 C) but to consider max.permissible temp. indicated in name plate (which is 55 C). Please correct me if I am wrong. Let me ask one (perhaps...

Hello, We have recently installed a 15MVA , 66/11kv, Dyn11 transformer of which cooling is ONAN. Unfortunately we lost its manual from our station. When it was fully loaded we found that the Winding Temperature and Oil Temperature is compared other generator transformers in the same station...

It is not a school thing. I have seen many battery chargers are with SCRs of which the rectifier transformers are connected in delta on secondary side. This is the reason for asking aboutit. Thanks. regards, zkz

Hello, Thanks for the explanation. I understood like this: Delta connection is provided for circulating the triplen harmonics produced by SCR rectification in short pulses within delta winding and not allowing those triplen harmonics back effected to supply system. Please correct...

Sir, Normally rectifier transformers used in Battery Chargers are found with Star-Delta configuration. Why secondary side is given as delta? What is the disadvantage if secondary side was Star? Thanks in advance, with regards zkz

Hello, As already pointed out, if you are meaning about Restricted Earth Fault protection (i.e., protection against the earthfaults occcuring in the portion between the phaseh CTs and Neutral CT), you have to use CT same ratio. Please note that there are other factors which are also to be...

Hello all, Thanks for the replies. Let me go through the directions you pointed out. I shall comment after that if necessary. Attention Edison123: This small unit is supposed to connect to LT supply, i.e., 415V supply. Presently we are not having any unit working in...

Hello, Sorry for replying as I was out of station. Actually, I am from Kerala State Electricity Board's side. So I have to propose the protections which are to be installed before connecting to KSEB's grid. KSEB is new in this. We have no previous experience. Regards, zkz

Hello, One small power producer wishes to connect his 5 HP induction generator to Kerala State Electricity Board's grid to supply power. What are the protections to be provided to the generator and to the turbine? What are the other protections to be provided to isolate...

dear Kh2, When a fault occurs on LV side, fault path includes transformer impdeance in addition to source impedance and other impedances upto transformer. But for HV side fault, the transformer impedance is excluded. Please note that impedance of a transformer is...

Transformer MVA = 1 MVA Percentage impedance = 5 HV side L-G Fault current = 2723 A If we assume L-G fault level = L-L-L fault level, Per unit impedance = 5/100 = 0.05 HV side fault level = (1.732*24.94KV*2723A)/1000 = 117.62MVA LV side fault level = 117.62/(1+(117.62/1)*.05)=17.09 MVA LV side...

hello, Can you please provide transformer MVA rating, percentage impedance and fault level on HV side? regards, appunni

dear sir, Sorry for belated reply. There was no noticeable heat in the shaft. Recently we balanced the rotor. Now UGB vibraion shows 1.6 mils (originally it was 6.2mils) , LGB vibration is 3.0 mils (originally it was 1.8mils) and TGB vibration is 2.6mils (originally it was 2.6...

Sir, You are right. We are talking about one of Idukki generators which is approximately 30 years old. regards, appunni

Sir, We use proximity sensor for the IRD 5806 online monitor and Direct Prod Velocity Pickup (Moving Coil Type) for IRD 350 analyser. The manufacturer says the direct prod pickup can be used for speed as low as 50cpm Now we take vibration displacement. There is option for measuring...

dear sir, Ours is overhung rotor ie the thrust bearng is above the rotor. The portable instrument we use is IRD Mechanalysis model 350 vibration analyser and Sendig 903 FFT analyzer. We measure the casing vibration ( support vibration )using the latter one. The body vibration was less than 50...

Sir, We have a 130MW generator (375RPM vertical hydro generator) in a powerhouse. When I took charge of Electrical Maintenance Engineer in that power house, I noted that the UGB vibration reading channel of Vibration monitor of that unit was found blocked. I also found that the LGB...

Thanks for explanations. regards, appunni

Thanks for valuable replies. Mr. Gunnar says about 100mA to 1A while Mr.Wolf says about 100A. I hope more explanations will be there about this matter. regards, appunni