To Parallel or Not to Parallel?

[mbrooke]

Remote building relying on on-site power. Parallel all the gens or have them power the building as multiple stand alone units? The 100kw units will be replaced with 200kw units so as being a full back-up to 1A and 2A.

 

[petersonra]

I am just curious about something. It seems you have 4 possible generators that can power the loads labeled as ACS. Are they so critical that they need that level of redundancy? That's three transfer switches that have to work correctly to power those loads.

 

[mbrooke]

I am just curious about something. It seems you have 4 possible generators that can power the loads labeled as ACS. Are they so critical that they need that level of redundancy? That's three transfer switches that have to work correctly to power those loads.

Correct. Life safety and critical operations. 4 gens.

I'm debating that but don't have much expertise to go by. As whole the building already has redundant power. On the other hand I'm not sure how reliable (available) those gens will be with 24/7 operation and routine maintenance vs a standard utility source in comparison.

 

[zbang]

Do you want N+N or N+1 (or +2) redundancy? My first take is to parallel all the large gens- gives more operational and maintenance flexibility. Also makes it easier to add capacity down the line. Downside is the paralleling gear can become the single-point-of-failure (SPOF).

For reliability, with proper maintenance.... and using gensets built for 24/7 operation instead of standby, you should be OK. I'm sure the manufacturers would love to talk with you about that.

 

[mbrooke]

Do you want N+N or N+1 (or +2) redundancy? My first take is to parallel all the large gens- gives more operational and maintenance flexibility. Also makes it easier to add capacity down the line. Downside is the paralleling gear can become the single-point-of-failure (SPOF).

For reliability, with proper maintenance.... and using gensets built for 24/7 operation instead of standby, you should be OK. I'm sure the manufacturers would love to talk with you about that.

I know they'd want to sell me paralleling gear. They do it with hospitals all the time despite just how much can fail.

N-1, N-2 ect will be dependent on the gen's availability.

As I'm reading Onan/Kohler/GE literature you have standby, prime and continuous.

I'm not sure what to make of it all, or if 900 rpm generators would be a better option. Though I've never actually dealt with a 900rpm unit.

 

[zbang]

I haven't dealt with 900RPM units, but it's common as size goes up, RPM goes down; and in theory they're quieter, not sure I buy that, but the sound is different. My gut says they'd be more reliable, too. You will want continuous-duty if they're going to run that way.

What the total load? Looks like maybe few hundred KVA, so in the grand scheme, not that big. While it's a much larger setup, you might look into how some off-grid ski resorts do it (they're paralleling MW+ sets, though).

Not sure how required backups (life safety/etc) play into this.

 

[mbrooke]

I haven't dealt with 900RPM units, but it's common as size goes up, RPM goes down; and in theory they're quieter, not sure I buy that, but the sound is different. My gut says they'd be more reliable, too. You will want continuous-duty if they're going to run that way.

What the total load? Looks like maybe few hundred KVA, so in the grand scheme, not that big. While it's a much larger setup, you might look into how some off-grid ski resorts do it (they're paralleling MW+ sets, though).

Yup, a few hundred kva. Though thats not to say I'm not thinking about MW+ systems either...



Do you know anything about the off-grid ski resorts you have in mind? I've never done one or seen the single line diagram/operational diagram of such a place.

Not sure how required backups (life safety/etc) play into this.

My plan is to have a small stand alone diesel unit, ATS and seperate dedicated system for the life safety circuits.