The Engineer's Place for News and Discussion®

 Previous in Forum: Electric Circuit Requirements Next in Forum: Type of Battey

### Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

### Rating Vote:

Power-User

Join Date: Dec 2009
Posts: 217

### Max Single Load of DG Set

06/19/2012 6:02 AM

Hi,

Can anybody tell me how to find max single load for a DG set?

I was referring to a literature which said - in hp it is 75% of rated kVA of generator output with starters(autotransformer or star-delta), but it is not matching the result.

For me, a 200 kVA DG set has 40 kVA of maximum single load - its calculation I could not verify.....!!

Thanks,

sks

Interested in this topic? By joining CR4 you can "subscribe" to
Anonymous Poster #1
#1

### Re: Max single load of DG Set.

06/19/2012 6:12 AM
Anonymous Poster #1
#2

### Re: Max Single Load of DG Set

06/19/2012 7:05 AM
Guru

Join Date: Jun 2010
Posts: 535
#3

### Re: Max Single Load of DG Set

06/19/2012 10:28 AM

What makes you think a 200 KVA generator set has a maximum single load of 40 KVA? What do you mean by 'single load'? There is obviously more significant information that you haven't shared with us.

Power-User

Join Date: Nov 2011
Posts: 205
#4

### Re: Max Single Load of DG Set

06/19/2012 11:33 AM

Think along the lines of what a DOL motor does when its starts up. The short term load can be 6 x FLC. Think what this might do to the DG - its going to sink it.

It a rule of thumb but as a single inductive load don't go more than 25% of gen set rating.

You need to be aware of potential brown outs when you start a large motor that might upset computers and sensitive kit.

Horrible loads include motors, SON lamps, welders etc.

Its an inexact science.

Power-User

Join Date: Dec 2009
Posts: 217
#5

### Re: Max Single Load of DG Set

06/20/2012 12:32 AM

thanx silverfox

but it appears as 20% because 40 kVA out of 200 kVA is 20%.(this is from standard source). Could you give me your source of information for 25% ??

Regards,

sks

Guru

Join Date: Jun 2010
Location: srilanka
Posts: 1804
#6

### Re: Max Single Load of DG Set

06/20/2012 1:37 AM

With DOL starter it should take at least 50% of rating and with auto transformer/star-delta it should take more. Although the starting current is high the powerfactor drops.

__________________
pnaban
Power-User

Join Date: Nov 2011
Posts: 205
#7

### Re: Max Single Load of DG Set

06/20/2012 3:14 AM

Like I said its not an exact science. There are many figures you haven't presented such as the generator impedance, the type of AVR fitted etc.

Starting a DOL motor again depends on what sort of mechanical appliance it is driving - a fan load is particularly bad.

Its an engineering judgement. Only you know the true load, type of load etc.