My prospective current in my load estimation is currently at 300A. The building is yet to be built. At what current level or load level is it advisable to not specify a direct connection to a 230/415V line but rather specify a local transformer and tap into the 11 to 13.5kv supply and step down on site instead?
Should I use a Transformer or Not?
- Thread starter Deebee101
- Start date
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Here in the US for a simple building with a 300 amp load you would not consider using 13.5 kv for anything.
The building itself will not use 13.5kv but will have a transformer on-site to step down the voltage. That is one case. The other case is to connect to the already existing 230/415V lines. I'm in Ghana.
ptonsparky
Tom
- Occupation
- EC - retired
I sure wouldn't want to have a spare transformer on hand. Our power utility stocks those, but that is here, and your situation may be entirely different. We don't know.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
The fact that you alrady have 230/415 available makes the case for not using a transformer. As long as the 230/425 system can supply the load why would you want to even consider using a higher voltage system?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
The power companies in the US rarely provide voltages above 480V unless the customer commits to purchase some thing like 10MWHR of power per year.
The decision is about the annual cost of power more than just the size of the service.
The decision is about the annual cost of power more than just the size of the service.
My question is can the 230/415V line supply a 300A load.
Interesting system. In Ghana, it depends on the load.
ptonsparky
Tom
- Occupation
- EC - retired
That will depend on how big of a transformer your utility provides.
Is this a calculated load, or actual?
Here it would be 277/480, and Yes, it would be provided at that level. 400 Amp services are common enough.
Only the utility provider could answer that. Yes, a 415 volt system with properly sized conductors can serve a 300 amp load, IF the capacity exists. But can the utility that is providing the 415 V support the load?
Most of the Utility transformers in Ghana are 500kVA. So one building drawing 300A is a lot. That's why I am asking.
ptonsparky
Tom
- Occupation
- EC - retired
400 amp, single or three phase, services are not uncommon IF the utility has existing infrastructure to provide it.
The customer would be charged to upgrade a utility from single to three phase.
The customer would be charged to upgrade a utility from single to three phase.
ptonsparky
Tom
- Occupation
- EC - retired
Ask the utility. It is what I would need to do.
Most of the Utility transformers in Ghana are 500kVA. So one building drawing 300A three phase is a lot. That's why I am asking. It is a calculated load, not an actual load.
Alright. Getting that information at the design stage isn't easy and the client needs the information to look for funds.
Thanks.
It is what it is. The utility has to provide that power no matter what the voltage is, so they are the ones who would know if their system can supply it. You are asking for less than 220 kVA, but it's the same 220 kVA at 415 volts as it is at 13000 volts.
No one here can answer the question beyond a theoretical "yes, IF..." Some phone calls or a polite office visit might get you the info you need.
The 415V transformers are usually around 500kVA and the 13000V transformers are around 10MVA. So getting a higher voltage and stepping down yourself gets you access to more power. I will try the phone call.