4000 amp manufacturing facility

[hurk27]

In my area/industry 13.8kV is pretty much the standard for large and new plant distribution voltage - and is the current ANSI standard for 3 wire distribution voltage.

http://static.schneider-electric.us/assets/consultingengineer/appguidedocs/section4_0307.pdf

Here as with Jim we also have 12.4/7.2 kv WYE system as the main MV local 3 phase and single phase feeds with 69kv deltas to the local substations and 138kv deltas to the major area substations that combine the many feeds from the generator plants that feed the local substations with the 69kv.

But some large industrial customers can have 69kv delta or like in our case at steel mills we have our own multiple 69kv feeds from our own local co-gen plants and 4 sets from our south Chicago plant with a few 138kv feeds from the utility as back up that is transformed down to 69kv then set up on transfer switch's that feed our main in-plant substations.

But I do believe (I would have to look it up) that a 13.8 delta is offered by our utility to plants with allot of motor loads as loosing a phase ahead of the transformer on a delta doesn't bring down the plant if the transformers are sized for continuation as an open delta.

We have some industrial plants including our own steel mill that does use 4100 but its all in-house and only after a in-house substation that the utility feeds the 12.4, 13.8 or 69kv to, but it is not a normal voltage supplied by our utility and they wouldn't have metering equipment for it.

So to the OP allot will depend upon what the local utility offers for that area, and the available power for the area or the utility can add the cost of up sizing or running new lines back to a substation with enough surplus power for the extra load.

Also another figure many utilities will ask for is peek demand which is what your largest motors will pull when starting up and if more then one starts at the same time they will have to be added up, some won't allow you to consider VFD's if they can be operated in by-pass mode.

 

[Haji]

Choosing 13.8kV, 12.47kV, etc., is not random. It depends on the size of the load to be served.
As for commonality of 13.8kV plant distribution, polling may be required as indicated by previous posts.

 

[iceworm]

...But I do believe (I would have to look it up) that a 13.8 delta is offered by our utility to plants with allot of motor loads as loosing a phase ahead of the transformer on a delta doesn't bring down the plant if the transformers are sized for continuation as an open delta.....

I don't see this working. Looks like the xfm has one winding fed single phase and the other two windings fed in series - single phase.

ice

 

[jim dungar]

I don't see this working. Looks like the xfm has one winding fed single phase and the other two windings fed in series - single phase.

ice

Open delta is a not uncommon connection.
Removing a transformer does not change the relationship between the L-L voltages.
It is not the same effect as removing one of the lines.

 

[iceworm]

Open delta is a not uncommon connection.
Removing a transformer does not change the relationship between the L-L voltages.
It is not the same effect as removing one of the lines.

Uhhh .... Yes. All that you say is true.

Jim -
May I gently request you read the posts.

Originally Posted by hurk27
...But I do believe (I would have to look it up) that a 13.8 delta is offered by our utility to plants with allot of motor loads as loosing a phase ahead of the transformer on a delta doesn't bring down the plant if the transformers are sized for continuation as an open delta .....

ice

 

[jim dungar]

Jim -
May I gently request you read the posts.

:ashamed:
I do not always think of a single conductor as 'a phase'. I know our industry uses it this way nore often than not, and usually it is best to go with the flow. So in this case, knowing hurk's experience, I simply read a meaning into his post rather than the exact words he used. Isn't this how misunderstandings are started?

 

[hurk27]

Uhhh .... Yes. All that you say is true.

Jim -
May I gently request you read the posts.



ice

You are correct as I miss stated it, I shouldn't have said ahead of the transformer as it should have been a phase at the transformer bank meaning the loss of one of the primary windings would still provide 3-phase power to the secondary but at a reduced power level (57.7%) Hey I was tired that nite LOL:slaphead:

:ashamed:
I do not always think of a single conductor as 'a phase'. I know our industry uses it this way nore often than not, and usually it is best to go with the flow. So in this case, knowing hurk's experience, I simply read a meaning into his post rather than the exact words he used. Isn't this how misunderstandings are started?

From what I was told is that using a delta primary, if there is a loss in one of the windings and the transformers are over sized enough the plant could keep on running in an open delta configuration while the bad tank is repaired or replaced, and is why deltas are common in industrial installations.

Here is a little video that explains it a little: OPEN DELTAS