Alternators

Hi All

In addition to Mr Hameedullah Ekhlas Comments -

Two unqual rating of the Alternators / Gensets can be synchronised easily.

Synchronising has two parts -

1. Paralleling the Gensets

2. Load Sharing

Paralleling has been beautifully explained by Mr Hameedullah Ekhlas.

Loas Sharing - Thumb Rule - the Load on the genset should be equal % of their Ratings. e.g if you have 2 Gensets of 1000 kw , 750 kW & the Load is 1400 KW, Means your Requirement is 80 % of the total Generating Capacity, Hence both the Gensets should be loaded to 80 % of their Capacity viz - 800 kW & 600 kw respectively.

Thanks

GA for a good answer.

The only thing that I would add is that "doing it wrong" can throw one or both alternators out of the building. Someone could get hurt, you REALLY have to know what you are doing.....

Thank u sir ... it is a good answer :)

Possibly, it depends on the application and size of the alternators. Can you please provide more information, is this for car alternators on a 12V DC common bus within a vehicle or something else?

You can run them parallel only if you are able to synchronize them. But there are some conditions for generators (or other utility power) to synchronize. See the thread http://cr4.globalspec.com/thread/43318 for detail of the conditions.

- MS

Yes, provided steps are taken to ensure that voltage and phase angle criteria are met.

Parallelling of 2 Genset has been explained by others...

Your question: Unequal capacities? Yes they can be paralleled but you must have a Load sharing Capability (usually standard nowadays with the parallelling panels). this load sharing operation must be done by a qualified person who knows the equipment being used. It consists of adjusting what is called the DROOP on each governor so the load is shared according to each generator's capacity. Ex: if A = 1000KVA and B = 500KVA, and the load is 1000KVA, then A will share 2/3 of 1000 = 666.66 while B will share 333.33 making the total of 1000 kVA.

The setting of the sharing process differes a little from one make to the other but the principle is the same. You Must Know What You Are Doing (Capital for warning not shouting!). Otherwise, One genset might take more load than its fair share (Proportional to its capacity) and be overloaded ... tripping or else.