Utility companies scope of work for transformers

[mehdi1351]

Hello,
I want to know what are the scope of work and services of the utility companies in regard with installation of a step-down 7MVA transformer?
I am guessing they need some critical info like transformer sizing calculation, proposed location main conductor sizing etc.
What I want to know is whether they will provide the following services:
1- installation of transformer
2- Supply and installation of the main power cable from the grid to the primary of the transformer
3-Supply and installation of the cable from the secondary of the transformer to switchgear

 

[jim dungar]

Each utility will have their own rules and requirements, you need to contact yours.
But in general,
1a. The pad and all underground conduits is the responsibility of the user.
1b. The actual transformer installation is by the utility.
2. All primary installation and conductors is done by the utility.
3. All secondary installation and conductors is done by the user.

 

[electrofelon]

Each utility will have their own rules and requirements, you need to contact yours.
But in general,
1a. The pad and all underground conduits is the responsibility of the user.
1b. The actual transformer installation is by the utility.
2. All primary installation and conductors is done by the utility.
3. All secondary installation and conductors is done by the user.

I would just also add that sizing is up to the utility. Every utility I have worked with establishes the transformer size.

 

[mauk]

7MVA is well beyond the normal limits of a secondary service for most of the utilities in my area. This would likely be a primary-metered service, with all transformation & distribution equipment being customer responsibility.

 

[mehdi1351]

I would just also add that sizing is up to the utility. Every utility I have worked with establishes the transformer size.

Oh, really? So I just need to prepare the load demand list and the rest would be on the Utility side? what about the growth and safety factors in the size of the transformer? will that be set by the Utility people as well?

 

[jim dungar]

Oh, really? So I just need to prepare the load demand list and the rest would be on the Utility side? what about the growth and safety factors in the size of the transformer? will that be set by the Utility people as well?

Typically you just need to tell them what you want now or in the near future. If they own the transformer they do not want to pay for losses that are not necessary. Your customer will be expected to have any future expansion approved by the utility.

Future expansion should be discussed with them as it may affect the infrastructure or, as mentioned above, you may exceed their service size at that voltage.

 

[Julius Right]

Usually, if the secondary distribution is only for one consumer, then they can instal the transformer but, the consumer has to pay the expenses. If the consumer gets only a part of the transformer supplied load, the Utility has to deliver the power supply up to the point of supply required. Some of the expenses-mainly the supply cable and the breaker- is supported by the consumer.
If the transformer is located on Utility yard the Utility provides the grounding.
The maximum transformer power for low voltage distribution in IEC World is 3 MVA.
China -for instance- delivered a 7 MVA Oil Immersed Power Transformer when
the primary voltage of the transformer is 33 KV and secondary voltage is 6.6 KV,
[50 Hz and according to IEC 60076 standard].

 

[Hv&Lv]

7MVA? What is your primary/secondary voltages?
What's the application? That matters also. What's the POCO? That matters as all utilities have their own rules. You give them a number and you exceed it, you will most likely be paying for that installation/change also.

 

[mehdi1351]

7MVA? What is your primary/secondary voltages?
What's the application? That matters also. What's the POCO? That matters as all utilities have their own rules. You give them a number and you exceed it, you will most likely be paying for that installation/change also.

Based on the final load list, finally I decided to get 2x 3MVA feeding into 2 separate switchboard (rated for 3000A). I am not sure about the primary voltage as I believe it is on Utility's baby to care, but I need 480VAC 3ph on secondary for the facility.
The application is to feed into a plant which is going to be built on Longview Texas.
The POCO would be Swepco, I guess?

 

[tortuga]

Once your above 5mva voltages like 4160/2400 pencil out, you'd have a 600A service at that voltage.

 

[electrofelon]

Based on the final load list, finally I decided to get 2x 3MVA feeding into 2 separate switchboard (rated for 3000A). I am not sure about the primary voltage as I believe it is on Utility's baby to care, but I need 480VAC 3ph on secondary for the facility.
The application is to feed into a plant which is going to be built on Longview Texas.
The POCO would be Swepco, I guess?

You can decide all you want, but I would highly recommend nailing down who the POCO is, look at their spec book and submit an application and get your site visit.