600kw cogeneration connection

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fjrivera

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Greetings to all.

Electrical distribution of my facility has a main 5MVA 38kV - 8.32kV transformer. From this transformer, four (4) transformers are connected stepping down from 8.32kv - 480V/277V. The capacities of these transformers are 750KVA, 750KVA, 1500KVA and 1500KVA. Then, from each transformer, switchgears are connected. Switchgears consist each of a main entrance, transfer switch and distribution panel.

I want to connect a 600kw 480V/277V cogeneration to one of the 1500KVA8.32kV ? 480V/277V transformer. The switchgear of this transformer consists of a main 1600A entrance, a transfer switch for a 1250KVA generator and a distribution panel with 1600A bus bars.

Possible connections that I can think of are

1) Grid connected directly to 1600A distribution panel bus bars. Using a monitoring meter to avoid back feed to POCO and avoid using the 480V/277V transformer as step up transformer. One drawback is that at some instances if existing loads are lower than 600kw then cogeneration need to be turned off.

2) Grid connected using a step up transformer 480V ? 8.32kV and connection to the facility 8.32kV distribution.

Any suggestions?
 

kingpb

Senior Member
Location
SE USA as far as you can go
Occupation
Engineer, Registered
Electrical distribution of my facility has a main 5MVA 38kV - 8.32kV transformer. From this transformer, four (4) transformers are connected stepping down from 8.32kv - 480V/277V. The capacities of these transformers are 750KVA, 750KVA, 1500KVA and 1500KVA.
8.32kV is a non-standard voltage, what voltage class of switchgear are you using; 15kV?

Then, from each transformer, switchgears are connected. Switchgears consist each of a main entrance, transfer switch and distribution panel.
Don't understand what you mean by transfer switches.

I want to connect a 600kw 480V/277V cogeneration to one of the 1500KVA8.32kV ? 480V/277V transformer. The switchgear of this transformer consists of a main 1600A entrance, a transfer switch for a 1250KVA generator and a distribution panel with 1600A bus bars.
What type of co-generation is it, and how much load is on the switchgear you want to connect too?

1) Grid connected directly to 1600A distribution panel bus bars. Using a monitoring meter to avoid back feed to POCO and avoid using the 480V/277V transformer as step up transformer. One drawback is that at some instances if existing loads are lower than 600kw then cogeneration need to be turned off.

2) Grid connected using a step up transformer 480V ? 8.32kV and connection to the facility 8.32kV distribution.

I assume you mean "Bus" connected, not "Grid" connected? Again what type of co-generation, and I would assume your loads are greater than the 600kW not less.

At 600kW, you do not want to use a voltage greater than 480V, especially if it is a non-standard such as your 8.32kV. This would cost you much more than using a step-up transformer.

In general, you want to connect the co-generation to the bus you are going to need to power. I assume you can't for some reason connect it to the 480V buses directly. But you will need to have load shedding capability to make sure you don't have more loads than the co-gen can handle.

Perhaps you could post a one-line sketch of your system.
 
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