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noel: some questions: 1-how old are your contactors? ( no mechanical problems? ) 2-ratings of equipment? ( motor,contactor,etc.) 3-always is the same equipment failure or are differents equipments with the same failure ? 4-have you capacitors in this equipments ?. I think you need add a...

LDMaughan: Only to add a little more: The color of the phases have not definition like "standard", however is common practice to use the NEC definitions ( like jspilogon said ), only in case of "high leg" usage, (in phase C) is orange or red. Also is very common find voltages 120/240 Volts (...

thanks tinfoil: Scott conection have the possibility of make 2 to 3 phase, 3 to 2 phase AND 3 to 3 phase. Now I have some information that makes to me able to make some TTR tests and others to rewind this TR. Thank you very much to all your responses.

thanks mc5w: Im sorry for not be enough clear about my question, my doubt is about the 3phase-3phase Scott transformer conection; after a search in the web I found some information but even it is not totally clear to me how locate the neutral point in the secundary winding. Im tryin to help to a...

thanks jghirst: Im looking for vectorial drawings and relationships about this kind of tr conection, im tring to stablish the angular displacement and to make some calculation about voltages and currents. Please advise, and thank you very much.

hi to all!! I'm looking for any drawing ,paper or web page about conection scott for trafo's. If somedody can help me please advise to me. Tanks a lot in advance.

And what about in fault conditions? supossing the same rating in HP but different conection star or delta? Thanks a lot Alfredo Corona

Dear All: After of read all the opinions of everyone, I think that the most important thing is understand the theory of operation ( according the original post ) of this very simple issue. I think that everybody ones that understand this ( and have a little of experience in field )kwnows what...

Here in Mexico, the " high leg " must be placed in phase C ( or 3, like you want ), according the good description of placements of phases descrites by RHB155. You would be carefully when working in a delta conection of TR secundaries 3p-4w. Saludos. Alfredo Corona Mexico

HighPotential: Maybe making a " fear analisys ", you will have your own answer. Saludos. Alfredo Corona Mexico

Thank you, Pract Eng Saludos

Thanks a lot for your responses. I'm sure that I don't have voltage drop since I've cheched incoming line volts and output of ballast and boths are OK. Ballast,contacts and tubes are all new. RadLight Please excuse me, but I can't understand when you said "Rapid start requires a 25 mm...

Hi to all Does anybody knows were I can look for any spreadsheet for electrical calculations ( conductors sizing, raceways, etc. ). Thanks a lot in advance.

Dear friends: Now I have a trouble with the operation of a ballast and the fluorescent lamps of a comercial refrigerator. I'm not sure if the ballast is the proper to operate the lamps ( Ballast is ADVANCE Cat. No. RC-2S102-TP and the lamps are -2 pieces- F48T12CWHO 60 Watts), the problem is...

Hello to all Can anybody please describe the color of conductors to install in low voltage, according (USA) NEC 2002?? I'm in Mexico and is the NOM-001-SEDE-1999 little different to NEC, and Im trying to evaluate a PC program ( according the NEC) to calculate circuits in low voltage and the...

Hello to all Can anybody please describe the color of conductors to install in low voltage, according (USA) NEC 2002. I'm in Mexico and is the NOM-001-SEDE-1999 little different to NEC, and Im trying to evaluate a program ( according the NEC) to calculate circuits in low voltage and the results...

hi guys!!! thanh you very much for your responses. I hope more people have some experience in this case ( if somebody have a system simmilar in operation please let me know yours results/recomendations ). Thanks in advance. Alfredo Corona Mexico

thanks for sus responses. Probably Im not explain very well the option to protect with this system to transformers, Im refer to protect THE LOAD in secundary ( connected in Y ) of transformers, against GF ( lost of phase will work good this system ??? ). Just now Im thinking about it, because...

hello to all Before than other thing,please excuse my english, i hope somebody can help to me in this cuestion. Some time ago i see in a old starter for winding rotor motor ( by resistances ), a system that i think is to provide protection to the motor for unbalanced current and/or ground fault...

henkv: What kind of load move this motor? Do you know if not have problems with the peaks of the drive? Any problems with the drive before the failure? Alfredo Corona Mexico