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Shaheed... something is unclear. The %Z value provided by the Testing Company for Tap #3, is certainly in the ballpark! At least for the rated parameters of the Xfmr, which are: 20,000 kVA, 11kV, and A = kVA /[sqt(3)x kV] ! But if you want greater accuracy I need to know Tap #3 V and A...

Shaheed... two questions: 1) How many taps are there? 2) What are Nameplate Volts & Ampere listed for Tap 3? Regards, Phil Corso

Know-How ... your question, "... to what extent will this affect the generator output ... ?" led me to conclude that your intent is to use the original 60 Hz machine, but operate it at 50 Hz! Please confirm if my conclusion is correct! Is so, the conversion will have a negative impact on the...

Assylbek Mukhanov... as a start can you at least provide some detail! Did the failure occur to the TG-unit: a) While the unit was in operation? b) When the unit was being started? c) While the unit was being synchronized to another source? d) When the unit was being stopped...

Halfdice... my Gi.Fi.E.S method (pronounced Jiffys) can be used to solve your problem:<pre> Gi for ‘Given’. Fi for ‘Find’. E for ‘Equation’. S for ‘Solution’.</pre> Given: A 3-phase Transformer; rated capacity kVA, 500; kVpri, 4.160V; kVsec, 0.480; Imp Z = 5.5%; and the transformer...

Victor, without pre-fault and post-fault parameters, I can only address your original question: Yes! Upon switching it on the UG cable behaves like a shunt-capacitor! And, although the steady-state current (20A) is relatively small, the transient inrush and more importantly, its duration...

Shaheed... What is the motor's rated voltage? Were the brushes "lifted" so that there is no contact with the commutator? Phil

Shaheed... I apologize for my incorrect identification of components: I should have said "brush-gear" instead of "slip-rings" and "field" instead of "stator!" Phil Corso

Shaheed... one more quesion: 10) what was IR reading of stator-winding? Phil

Shaheed... correction to my earlier post. Last Archive Thread should have been: o 1239772210! Phil

Shaheed.. If you haven't already done so search the Control.Com archives! Specifically: o 1001509379 ! o 1026224486 ! o 1239792210 ! My suggestions are: 1) Perform the Polarization-Index test just after the motor has been de-energized, that is, with the motor "Hot" ! 2) Use a...

Shaheed... before "cutting out" suspected wiring please answer the following: 1) What is the motor's rated voltage? 2) What is driven-machine? 3) What is Enclosure-type? 4) What is Insulation-Class? 5) How long has it been in service? 6) When was IR last measured? 7) What...

Dave... you provided DC-Link voltages. Can you provide additional detail: 1) Input supply ph-ph voltages? 2) Are the trip events occuring at about the same time in a shift? 3) Are the two drives identical with regard to physical parameters: a) connected to the same supply bus? b)...

Victor... several questions: 1) Is Generator neutral NGR earthed? 2) Is 33kV system solidly-earthed? 3) Is UG cable 3 or 4-conductor? 4) Is UG cable metal-shielded? 4) What is MVA capacity of step-up Xfmr? 5) Did Generator trip? 6) If tripped, which protective device was...

Santhosh... a simultaneous 3-phase short circuit at or near an alternator’s terminals, can be represented by an Alternating-Current wave having a large value at fault initiation which then decays to a steady-state value some time later. The three time periods normally assigned the transition...

Abbs... another question: 7) Is the xfmr's magnetic-core 3-legged or 5-legged? Phil

Abbs... the 3-winding Y-Y-Y xfmr, especially one with its 3-neutrals grounded, usually results in "Raised-Eyebrows" due to zero-sequence impedance issues! Following are additional questions: 3) Is the xfmr construction of the Core-type or Shell-type? 4) Do you have access to the...

Gen Man... if your machines are the brushless type, I would be more inclined to look at Pilot-Exciter circuit! Regards, Phil Corso

I&CAdvisor... If you intend to use cooling-air, its source must be from an unclassified area! In addition, the flow of air must be exhausted into an unclassified area! Regards, Phil Corso

Gjorgi... the parameters you seek, can be found in the following IEEE Publication: IEEE Transactions on Industry Applications Vol. IA-21, No. 4, May/June, 1985 "Protection of Induction Motors Against Unbalanced Voltages" Authors: Paul R. Cummings, John R. Dunki-Jacobs, Robert H...