Generator Redundancy Operating Philosophy (N+1)

Instead of N+1,won't it be economical to have N/2+N/2+N/2,with one of them as standby?.

No, because then you would need 4 generators instead of 3, 5 instead of 4 and so on.

It is better to go with the minimum number of larger generators so that the Generators are running in the minimum load sweet spot (35-45%) rather than having more generators and they are all running at 25% well below the minimum.

As per previous discussions, diesel generators will have a minimum load requirement to prevent glazing of bores, damaged seals etc.

Regards,
Sapper

You don't need 4,3 would be ok because most probably only 1(N/2) may breakdown & the standby set will take over. Meanwhile you repair the defective one and keep it ready as standby.

You say 'tomahto' I say 'tomayto', aren't the two concepts the same (assuming we're talking about identically sized units)?

As others has said, if the customer wants to talk N-1, then speak to them in their "language". Other customers could very well want to talk N+1.

pwr2thepeople,

After reading the links you provided, seems I learnt something today... Thanks.

In data centres, redundancy is only referred to as "N+1,2,3etc"

In Power generation and distribution systems, seems that redundancy is defined as either "N+" or "N/" or "N-" depending on perspective, design and possible where you got your higher learning from.

Always a good day when you learn something!

Regards,
Sapper.

Computer data or voice or video could be recorded or stored using standby power but electrical energy storage is the biggest challenge requiring spare capacity or standby.

Not talking about the Data.

This is about Data Centre Infrastructure (Power, HVAC & Mechanical) and Utility Distribution.

Regards,
Sapper

If I were you, I'd do a quick search for "N-1 generators". You won't find any, but you may find an explaination of "N" numbers as they relate to multiple generators.

You should know this for your next client, in case you are pressed for time.

I wrote in another thread that Rule 1 is The Client is always right and if in doubt refer to rule 1. Obviously I'll have to revise rule 1!!!!!

N-1 is common when referring to electrical redundancy in transmission and distribution sysstems. I would read the customer as meaning that they want N+1 mechanical redundancy.

N-1 or N+1 terms have different references. When the operations engineer says N-1 design, he is meaning that the system is stable with trip of one of the machines.

When the designer says N+1,he is meaning that if N machines are required to supply the load, one additional (N+1) machine has been included in the design.

Thus, we can say for Operation security under N-1 contingency (loss or trip of one of the machines), the system needs to be designed with N+1 (required no. of machines to meet the load + 1 extra) machines.

Hi raqhun,

I would like to ask how I will size an equipment with "N+1" or "N-1"? Is there any criteria or standard to use?

Is there any standard to be used in choosing of "N" contingency considering it is not Client preferences.

thank you in advance.

Regards,

Emer2830