closed wye delta to wye wye keeping rotation

[T-Man]

Rotation and phase angle and position are two different parts of three phase transformer wiring. You can change rotation by changing two primary phases or messing with the secondary connections. Delta is a three wire connection, usually 240 or 477 voltages. Wye connections are 4 wire connections that include a neutral grounded leg and the 3 phase voltage is usually 208 or 416. Customers that use three phase should have motors or equipment that is designed to operate in one direction, so finding rotation is important. in future applications it's a good policy to mark rotation in a convenient location so if you change out the source you know which way to set up the new set. You can turn off all the breakers on the customers side then energize the tub and only turn on one breaker to one motor to see if it turns in the correct direction. Usually larger 3 phase motors have an arrow on their case showing their correct rotation. Wye and Delta can rotate in the same direction the voltage may be a problem in some cases. You can use vectoring, rotation meters, and trial and error as long as your not damaging customer equipment.

[Old Line Dog]

Rotation and phase angle and position are two different parts of three phase transformer wiring. You can change rotation by changing two primary phases or messing with the secondary connections. Delta is a three wire connection, usually 240 or 477 voltages. Wye connections are 4 wire connections that include a neutral grounded leg and the 3 phase voltage is usually 208 or 416. Customers that use three phase should have motors or equipment that is designed to operate in one direction, so finding rotation is important. in future applications it's a good policy to mark rotation in a convenient location so if you change out the source you know which way to set up the new set. You can turn off all the breakers on the customers side then energize the tub and only turn on one breaker to one motor to see if it turns in the correct direction. Usually larger 3 phase motors have an arrow on their case showing their correct rotation. Wye and Delta can rotate in the same direction the voltage may be a problem in some cases. You can use vectoring, rotation meters, and trial and error as long as your not damaging customer equipment.

While all that may be true Ray....I'm still wondering why Blast changed out all 3 transformers??? AND...where did al the Oil come from???

[lewy]

The original poster could have possibly hooked it up open delta to get his rotation, then hung his new wye bank. It mite be the same as us in that we don't hook up delta secondaries anymore, if we get a bad 600 delta bank with 1 bad transformer we have to change the whole bank as well as we don't carry straight 600 transformers anymore only 347, so we hook them up 347/600 and they only use the 600.

[T-Man]

Good point Lewy, an open Delta would have given the customer service at about 57% of the original capacity. They could cut back and continue till a replacement tub/s could arrive on site.

[Old Line Dog]

So I had an outage I show up and find a bad transformer
In a wye delta bank the other two pots are covered in oil. I opt to just change out the bank. Company policy requires any new banks going up to be wye wye whenever possible. So I am unable to check rotation and going to the wye wye bank. Is there a way to make sure you get the rotation right every time in this case using vectors or other means or suggestions.

I think this thread has got REAL off topic, from THIS original Post. FIRST...why did Blast change out all three transformers? Which Transformer Blew? All this "What is the Rotation Crap"...is only being talked about, because Blast changed out ALL transformers...I repeat...WHICH Transformer Blew???? I would have never, changed out all 3 Transformers. Therefore...NO "Rotation problem". My call?? BAD Call!!! Changin out all 3 transformers.

[splinter]

I think something is amiss here, don't think you would just change voltages on a customer without letting them know to start with.

[Trouble1]

You can keep the same voltage and switch from wye/delta to wye/wye. Like rob says, it's up to the customer how they want to use the service. If there was a ground on it before you change the bank, it might get exciting.

Seems like every large company is starting to do this.

[Old Line Dog]

So I had an outage I show up and find a bad transformer
In a wye delta bank the other two pots are covered in oil. I opt to just change out the bank. Company policy requires any new banks going up to be wye wye whenever possible. So I am unable to check rotation and going to the wye wye bank. Is there a way to make sure you get the rotation right every time in this case using vectors or other means or suggestions.

I guess I'm just not really understanding your "company's" Policy Blast. the Wye/Wye Bank and the Wye/Delta Bank have 2 COMPLETELY Different reasons for being. All your "Rotation" questions aside...A Wye/Delta Bank is designed for Large amounts of 3 phase loads and moderate amounts of single phase loads. A Wye/Wye bank is designed for Large amounts of single phase loads and a moderate amount of 3 phase load. Are you a Rural Lineman? I'm sorry bud...I just don't understand your "company's" policy...basically, make everything a 208 Wye bank.... I ain't makin fun....I'm just tryin to understand, what to ME...is Fcuked up thinking. Course,....I ain't an "Engineer". :-)

[lewy]

[QUOTE=Old Line Dog;144238]I guess I'm just not really understanding your "company's" Policy Blast. the Wye/Wye Bank and the Wye/Delta Bank have 2 COMPLETELY Different reasons for being. All your "Rotation" questions aside...A Wye/Delta Bank is designed for Large amounts of 3 phase loads and moderate amounts of single phase loads. A Wye/Wye bank is designed for Large amounts of single phase loads and a moderate amount of 3 phase load. Are you a Rural Lineman? I'm sorry bud...I just don't understand your "company's" policy...basically, make everything a 208 Wye bank.... I ain't makin fun....I'm just tryin to understand, what to ME...is Fcuked up thinking. Course,....I ain't an "Engineer". :-)[/QUOTE

Really I never heard that before all our big customers get 347/600, very few get 120/208 and no new customers can get a delta service.

[Trouble1]

I guess I'm just not really understanding your "company's" Policy Blast. the Wye/Wye Bank and the Wye/Delta Bank have 2 COMPLETELY Different reasons for being. All your "Rotation" questions aside...A Wye/Delta Bank is designed for Large amounts of 3 phase loads and moderate amounts of single phase loads. A Wye/Wye bank is designed for Large amounts of single phase loads and a moderate amount of 3 phase load. Are you a Rural Lineman? I'm sorry bud...I just don't understand your "company's" policy...basically, make everything a 208 Wye bank.... I ain't makin fun....I'm just tryin to understand, what to ME...is Fcuked up thinking. Course,....I ain't an "Engineer". :-)

I think you are misunderstanding. 120/208 will always be replaced with 120/208. Nobody is replacing 240 delta with 120/208. What most companies are doing now is replacing straight delta 240 or 480 services with 138/240 or 277/480 and leaving the neutral off at the building. Basically giving them the same service except not delta anymore. I've heard it saves money somehow.