5000A Switchboard in outdoor enclosure

[Shujinko]

I have a client that bought 3 modular chiller plants which he got a great deal on because he bought it from someone who bought them but didn't end up using them. Long Story...hehehe.

Since he got such a great deal on this he didn't think of the electrical side of things mostly just the HVAC side of things. He wants to put it in the middle of a site without making a utility building for an electrical room. Therefore I'll need to provide a 5000A Switchboard with an weatherproof enclosure for all the modular chiller plants or (3) 1600A switchboards in weatherproof enclosures, one SB for each modular chiller plant. The system voltage would be 480Y/277V.

Which would be the better option (1) bigger SB service main or (3) smaller SB's service mains? What should I be considering code wise? What should I be considering specification wise? I have never spec'd gear this big (5000A) and want to make sure I am covering all by bases.

 

[infinity]

If this is a 5000 amp service one 5000 amp switchboard with 3 smaller main service disconnects would likely be the cheapest.

 

[augie47]

Comparing costs and taking into account the environmental effect of weather on the gear and anyone needing to work on it, I'd sure give more consideration to a utility building.

 

[Jraef]

Where is the 5,000A going to come from and how is it going to get there? that's where you need to start.

But I agree, at that level a building starts to look better. Think about having to work on a 5000A switchboard in the rain some day in the future...

 

[Cow]

I would look into transformer sizing first.

We were about to do a 4000 amp 480/277v service, but the transformer at that size wasn't common. It turned into two adjacent 2000 amp services with two transformers.

 

[petersonra]

Can probably get a cargo container and put that switchgear inside that

 

[zbang]

Can probably get a cargo container and put that switchgear inside that

Probably won't be able to get the required clearances- most are only 8' wide, and you'd still have to do doors and ventilation. If using indoor switchboard(s), one of those pre-fab metal buildings is a good option.

As other say, start with the source and let that drive the switchboard selection- you could end up with three transformers/SBs or you could have a large mass of conduits from somewhere else. (What's the overall supply voltage to the facility?)

 

[Shujinko]

Probably won't be able to get the required clearances- most are only 8' wide, and you'd still have to do doors and ventilation. If using indoor switchboard(s), one of those pre-fab metal buildings is a good option.

As other say, start with the source and let that drive the switchboard selection- you could end up with three transformers/SBs or you could have a large mass of conduits from somewhere else. (What's the overall supply voltage to the facility?)

480Y/277V is the system voltage. We would obviously have a separate service(s) for this. I think your advice is good about looking at the source transformer(s) because I am pretty sure the local utility is limited to transformer KVA size at about 2500KVA.

Anything code wise I should be looking at?

 

[Shujinko]

Can probably get a cargo container and put that switchgear inside that

Cool idea. You have any pics of examples of that?

 

[kingpb]

He wants to put it in the middle of a site without making a utility building for an electrical room.

Does that mean he doesn't want a building at all, or he just doesn't want to build a separate structure?

Who is going to own the transformer; i.e. is it utility provided or owner furnished?

How critical are the chillers to operation?

What is the location being installed; i.e. environment considerations?

Are the chillers installed next to each other, or are they spread out?

How far away will the transformer (if utility owned) or the utility power be from where the chillers are?

As you can see there are a lot questions needing answers that would make it more practical in helping with suggestions.

 

[iceworm]

... I'll need to provide a 5000A Switchboard with an weatherproof enclosure for all the modular chiller plants or (3) 1600A switchboards in weatherproof enclosures, one SB for each modular chiller plant. The system voltage would be 480Y/277V. ....

Some random thoughts - I'd be looking at life cycle costs as opposed to just installed costs. But that means the management has to be on board with considering lifetime maintenance costs:

5000A and 8% IZ = 62.5KA SCC (yuck) Likely not possible to get the incident energy to below 40 cal/cm2
How do you rack out a CB - outside and in the rain? Even with remote operators, one is still building tents.

Three separate units at 1600A each. xfm are 1500KVA at maybe 6%, 1800A (FLA) = 30KA SCC. With three units, maybe possible to take one off line. Still building tents, but it is de-energized.

5000A requires 10ea 1000kcmil, or 14 ea 500kcmil, fed from a 4MVA xfm
1600A requires 5 ea 500kcmil, fed from a 1.5MVA xfm

You have a nice project. Good luck. Let us know how it comes out.

 

[iceworm]

And, no, I don't think it makes any difference as to who owns the transformers.

Either way the customer is going to pay for the transformers, to heat the transformers, and for the maintenance on the system. The details are in a negotiated rate schedule.

One advantage for customer owned, is the 480 secondary can be specified to be HRG - which is my favorite for anything over 500KVA, and industrial.

For some inexplicable reason HRG 480V services cause utilities to go into convulsions.

 

[petersonra]

http://www.atlaselectricinc.com/products/e-houses-containers-trailers

here are some interesting options.

 

[kingpb]

And, no, I don't think it makes any difference as to who owns the transformers.

From a design standpoint it makes a difference.

A utility transformer may have limitations on where they want to set it, or the maximum size (KVA).

If it's owner furnished then you could make it direct coupled to the switchboard; depending on location, it may be better to go with a dry type.

You can split them up using three padmounted and do loop feed.

I'm sure there are others.

 

[ron]

Think of the source available and what is the short circuit rating of the chillers.

You may need smaller services to know down fault current or you may need a larger service to take advantage of that last MV feeder left in the vault for the equipment.

It is multi-factorial.....

 

[Shujinko]

Does that mean he doesn't want a building at all, or he just doesn't want to build a separate structure?

Who is going to own the transformer; i.e. is it utility provided or owner furnished?

How critical are the chillers to operation?

What is the location being installed; i.e. environment considerations?

Are the chillers installed next to each other, or are they spread out?

How far away will the transformer (if utility owned) or the utility power be from where the chillers are?

As you can see there are a lot questions needing answers that would make it more practical in helping with suggestions.

1. XFMR owned by the utility.
2. No stand-by power. Chillers are mostly for retail and commercial type spaces (non-critical functions).
3. Switchboard to be located in a Chiller Yard.
4. Chillers are within 10' of each other in the chiller yard.
5. Utility XFMR is roughly 100' away from the switchboard location.

PS: We are breaking this into 2 separate switchboards (services) because the maximum XFMR size for the local utility is 2500KVA.