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Sashi... I can't print the attachment(s). Are there 3 sheets or just one? Data still unclear! One sheet in Ohms, the other in percent, one 7500 kVA, the other10,000 kVA, and both refer to Dyn9! Please contact me at [email protected] . We can then post solution/conclusion to ConrolCom. Phil

Sashi... I must admit I've never had to deal with a Dyn9, so let's continue! Please furnish the Impedance per Tap figures as well as the Zero-Sequence value, shown on the Connection Diagram, because the values shown are illegible! Do you have the spec for the Dyn11 ? If so, then send just one...

Racer2.. I just leaISA, 2006, 461 pp., US$96 ISBN 1-55617-942-1 Racer 2.. Since time and speed are involved, I recommend "Advanced PID Control" by Karl J. Åstrom and Tore Hagghlund. Available in IEEE Book Store! Regards, Phil Corso

S... Here is some additional information... there are 4 groups of distinct transformer 'Vector groups' using the European standard. Please note there is no "9": o Group 1, having 0 degree phase-displacement, i.e., Yy0, Dd0, Zz0. o Group 2, having 180 degree phase-displacement, i.e...

S... Also check Board mfg serial numbers. Once had similar problem with 4 failures at time of commissioning. They weren't ABB, but another mfg reputed to be one of the the best! I found that the SN # happened to be in sequence, and it turned out the Batch was faulty! Phil Corso

S... The higher-voltage side should be capitalized, like Dyn9 ! Is this the case ? Further more, are you sure one has the digit "9"? Regards, Phil Corso

BC... Is source of supply grounded (earthed) ? If so is source of supply 3ph, 4-wire Wye? Or something called a 3-ph, High-Leg, having a 3-winding Delta transformer, but, one of the 3-windings is center-tapped to ground (earth) ? Regards, Phil Corso

Attached is the promised file. This procedure was then used by the parent company as a Commissioning Spec, on projects containing Diff'l Protection testing ! Transformer Differential Protection testing was accomplished by energizing the Xfmr 4-6% of its nominal rating ! Regards, Phil Corso

Anyone interested in a simple way to test Differential Protection for both a generator or a transformer? Phil Corso

jr94... Did you notice if the Differential-caused trips occurred on the same phase? Regards, Phil Corso

Mehboob... In reply to your question regarding earth-fault: If the generator is not a low-voltage one, but say medium voltage or higher, then the earth-fault current will be in the order of amperes, which is too low to be detected by the Differential-Protection device! Regards, Phil Corso

RP... I don't know why, but I can't down-load your diagram. Please send it directly to [email protected]! Are you sure the original configuration was a parallel 'Y'? And not a double-delta? Or even the Zig-Zag? Frankly, I don't a think a parallel 'Y' will be successful! If you can obtain the...

Mutahir.... 1) In your very 1st post you mentioned... "Mostly capacitive, i.e.,lighting etc." My question... How much? 2) Exactly which protective device(s) "Trip" the unit? Regards, Phil Corso

JoshD... Try a boat lift vendor. Regards, Phil Corso

MRasool... 1) What do you mean by "when a 15kW motor is turned-off after it is started"? 2) Do you mean a 'particular' motor? 3) Does it turns off by itself during the run-up? 4) Or, do you mean it is deliberately turned-off by someone before it reaches full speed? 5) Is the motor operated with...

Aung... At the top of the Introductory page tap on the Magnifying Glass icon. The word SEARCH will appear. Type in the File number. Remember it does not directly address your query. Phil

Aung... I didn't find it either under the file # above! But I did find it at File # 1026241679! Phil Corso

Aung... In order to learn about Resistor-Grounding or any other grounding method, I suggest you retrieve Automation.Control.Com File # 1245257675, titled "The Physics of MV Neutral Grounding"! It answers the often asked question "Why is the MV system-neutral grounded, especially when a 4th or...

Aung... Did you read the "SmilarTHreads"? Regards, Phil Corso

Gentlemen 1) My History With Areo-Derivative GTG! In 1964, as an employee of Esso Research & Engineering (now Exxon-Mobile), the 1st Aero-Derivative GTG in an Esso refinery was being commissioned. We were tasked to test flare-gas, and other gas-fuels. A newly acquired IBM-360 was to crunch very...