Cost/Benefit Using HV/LV contract for below 1MVA power demand

[adindas]

Could anyone help with the following please:
At maximum demand levels of between 500KVA and 999KVA a consumer can elect to take their supply at either LV or HV.
Has anyone done a design note comparing the relative merits of each approach such as:

Capital cost

Running / maintenance costs

Utility charges / Tariffs

Spatial requirements

Restrictions on plant space location

Program



Any help most appreciated.

 

[kingpb]

I cannot say I have seen a study on such, but roughly speaking, I know a MV breaker will cost approx. $35k each. Four LV power circuit breakers and structure would cost maybe $30k. I doubt you are talking about having a bunch of large motor loads, so any power you need for utilization voltage at say 480V is going to require additional step down transformers. This is going to be additional dollars.

1000 KVA is only 1200A service at 480V. I can't possibly see any financial advantage to using MV for this low of power requirement. Even if you did have a large motor, e.g. 500Hp, a soft start or VFD would still be more economical than using MV.

MV gear takes up more space, requires specially trained personnel to maintain, and definitely costs more.

 

[steve66]

The local utility did such a study for one of our clients (for free, believe it or not). However, they were pushing for single point HV metering so I wonder if the study is a little biased.

Anyway, it couldn't hurt to ask the utitlity if they are willing to do this. After all, I think they are the only ones that actually understand the rate structurres.