500 kva padmount xfmr

[PCN]

We have a 500 kva padmount transformer feeding a new building. The secondaries to the main building consist of 4 sets of 500's, that go through CT's in the transformer vault which is provided by the POCO.

Now they want to add an out building that will be powered from that same xfmr.....but metered seperatly. My question is, when we add that 5th set of feeders for the out building, can they be routed around the CT's in the vault to allow seperate metering say in a CT can on the out building?

Seems like a no brainer to me, but my boss (the P.E.)thinks this will not work.
I have not asked the POCO this question yet.

 

[augie47]

sounds like a POCO call to me.
I has been done here before.

 

[TxEngr]

I second Augie's recommendation. Check with the POCO before doing anything. The CTs may be for more than just metering - they may be part of the protection scheme for the transformer and bypassing them could cause a problem.

 

[steve66]

The power company may scoff at providing another service for the same customer at the same address.

Its probably one of those things the POCO could probably do, but they may not be willing to do.

Edit: So I'll third Augie's suggestion

Steve

 

[lakee911]

An alternative would be to run all 5 feeders through the CT and then provide an additional for the seperate building and simply subtract the additional building from the total.

 

[gobblerhuntr]

Dependent on what kind of CTs they are will determine how much headache it will cause the POCO, we do this sorta thing a lot and really don't haggle over having another service as lone as it is a separate building. Best bet is to call the POCO.

 

[hurk27]

Done here all the time.
But there are a few questions that the POCO will have for you when you ask them if this can be done:

1. What is the total calculated load of both buildings.
2. What is the largest combined start up load of all the motors of both buildings

You might have to fill out a signed load sheet, this is so you take on the obligations of liability if the transformer is over loaded if you give a (too low) figure.

sometimes they will welcome the added load if the original load on the transformer was not large enough, this is because a transformer becomes so inefficient when it is not loaded enough, and the POCO pays the cost of this power loss when the transformer is on the line side of the meter equipment.

but before any work or bidding can be done a POCO study has to happen or you might be doing the work twice.