Generator; Prime vs. Emergency codes

[hrlyman]

NEC Article 700 pertains to Emergency Systems and other types of required "Standby" systems. I am trying to find information on "Prime" power system requirements which I dont see anything specific in any part of the NEC. Any other ideas for regulations or standards?

This is a 6 megawatt prime power system using 6 - 1 meg 480V generators. All of the gens will synch to a main low voltage bus and be distributed by CB to a step up Transformer to 12.5kv. The high voltage (secondary) will come back into a high voltage fused distribution cabinet and go out to loads. There is no interconnection with any other utility sources, no co-generation, no transferring of power, this is the main source.

The one question that has come up is if the synchronizing circuit for each genset has to be automatic or if it can be of the manual type? Does anybody have knowledge of any code restrictions or standards that relate to this?

Thank You

 

[peter]

Does anybody have knowledge of any code restrictions or standards that [apply]?

I, personally, do not know anything at all about this.
~Peter

 

[dbuckley]

Given that we are in the 21st century, surely synchronisation should be fully automated...?

Can't see any specific reason why there would be regulatory chapter and verse about this, as it is a design issue, unless you bump into the requirements of legally required systems.

 

[rcwilson]

I am not aware of specific code for synchronizing equipment. It is just good engineering practice and is recommended in application guides and IEEE Standards like the color Book Series.

If the units are only taken on & off line 5-6 times per year by experienced operators, manual only synchronzing supervised by synch check relays might prevent damage from out oof synch closures. But the incremental cost of one autosynchronizer with six selector switches is well worth the expense.

 

[Cold Fusion]

NEC Article 700 pertains to Emergency Systems and other types of required "Standby" systems. I am trying to find information on "Prime" power system requirements which I dont see anything specific in any part of the NEC. Any other ideas for regulations or standards?

This is a 6 megawatt prime power system using 6 - 1 meg 480V generators. All of the gens will synch to a main low voltage bus and be distributed by CB to a step up Transformer to 12.5kv. The high voltage (secondary) will come back into a high voltage fused distribution cabinet and go out to loads. There is no interconnection with any other utility sources, no co-generation, no transferring of power, this is the main source.

The one question that has come up is if the synchronizing circuit for each genset has to be automatic or if it can be of the manual type? Does anybody have knowledge of any code restrictions or standards that relate to this?

Thank You

The specific answer to your specific question is:
No code restrictions
As rcwilison said, there are lots of standards

You are absolutely free to make this as simple or as complex as you would like.

Depending on the customer needs, a six gen, auto start, auto sync, load matching, add large VFDs and varing loads gets complex in a hurry. I've worked on a couple of these and they can be difficult to get to run smoothly and reliabily, with minimal intervention.

The NEC, while having many things to say about this sort of installation, has no useful guidance. In addition, it has some things to say that could be interperted to lead one into practices that are poor, even bordering on potentially equipment damaging.

And yes, there are reasons to have at least part of the system capable of manual operation - especially if being black for a significant time while one waits for the plc(s) to get fixed is an issue.

cf

 

[Last Leg]

NFPA 110 has Code standards for Generators

NFPA site
http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=72&cookie_test=1

You have to register to view the codes (cannot print), but it doesn't cost.
To the left click on, I think, 'List of Codes', or something like that. Click on 110 and follow directions.

 

[kingpb]

Stay with auto-sync. With multiple units you will also be dealing with load sharing. The new gen controls these days allow the boxes to talk to each other through shielded twisted pair. The gen rep can give you a lot of guidance and recommendations.

As far as NEC, it will not provide guidance because it is minimum requirements for a safe installation, not a how to cook book to design by.

 

[Cold Fusion]

Stay with auto-sync. With multiple units you will also be dealing with load sharing. ...

and var sharing, and base loading , and minimum loading. and ...

cf

 

[Cold Fusion]

... The gen rep can give you a lot of guidance and recommendations. ....

king -
I'm leary of relying on vendor/mfg reps. You're right, they can and will give you lots of guidance. I have found that most are excellent at pushing their own equipment regardless if it meets your needs.

cf

 

[kingpb]

king -
I'm leary of relying on vendor/mfg reps. You're right, they can and will give you lots of guidance. I have found that most are excellent at pushing their own equipment regardless if it meets your needs.

cf

I deal with the same folks when I need info and usually talk to the engineers directly, not reps. Your right, reps can be misleading at times, but that's where you need to have a good idea on what you want, Let them fill in the technical blanks. If someone is solely relying on the rep, then that is where you have to decide if your in over your head on the job. Maybe time to call the experts.