Generator sizes?

[DeanS]

Hi. Which is the larger generator.

4.8 Kva

 

or 3700Watt

 

my brain can't think and someone I know is asking me....

[Chewbacka]

4.8kVA is biggest.

 

Actually the 3.7kW is 3.7kVA assuming that the gennie and load both have a power factor of 1, and probably the gennie could not supply 3.7kW into a load with a power factor well away from 1.

[Tony Brooks]

Hi. Which is the larger generator.

 

4.8 Kva

 

or 3700Watt

 

my brain can't think and someone I know is asking me....

 

Well that rather depends upon the power factors (others who really know will chip in I hope) but taking 0.7 as some kind of power factor 4.8 Kva = 3.36 kw (3360 watts)>

[Hawkmoth]

It depends on the power factor AFAIK

Bob

Beaten to it

Edited September 1, 2016 by Hawkmoth

[Chewbacka]

 

Well that rather depends upon the power factors (others who really know will chip in I hope) but taking 0.7 as some kind of power factor 4.8 Kva = 3.36 kw (3360 watts)>

Agreed, but the point I was trying to make rather badly, is that a cheap 3700W gennie will not be capable of supplying 3700W into a power factor of - in this case - 0.7. And so I would expect the 4800VA gennie to still be more powerful.

[Tony Brooks]

I think that across a range of electrical equipment they will be very similar. With say a heater the 4.8 Kva one might deliver slightly more usable power (as we do not know the Kva of the other one) with motors and such like the 3.6 Kw one might be very similar.

[Tiggs]

http://www.allaboutcircuits.com/textbook/alternating-current/chpt-11/practical-power-factor-correction/

 

is a fairly simple explanation.

 

The generator rated at 3.6 kW has a theoretical output of 4.8KVA if the load has a suitable power factor - i.e. contains inductors or capacitors which take in and feedback energy.

[DHutch]

Equally, out generator, a honda EX1000 is rated at something like 0.86kVA , so make sure your looking at the specs not the model number!

 

Its like cheap watches where the '10M' model is splash proof, the '25M' waterproof to a meter for half an hour and the '100M' might actaully survive and hour in the pool.

 

 

 

Daniel

[cuthound]

Industrial generators are always rated at 0.8 power factor, unless specified otherwise. The ones I am familiar with range from 10kVA to 10MVA.

 

These generating sets have 2 ratings, "standby", whereby they will deliver their rated power continuously, with 1 hour in 12 at 110% of badged rating and "fuel stop", where the generator will produce 125% of its rated power, but is time limited, e.g. for a maximum of 250 hours per annum.

 

If you specify say, 0.9 power factor, then you get the same alternator driven by a more powerful engine.

 

None of which helps the OP. He needs to find out the power factor that the two generators are rated at to get a definitive answer.

 

Edited for clarification and spillung.

Edited September 2, 2016 by cuthound

[Horace42]

Hi. Which is the larger generator.

 

4.8 Kva

 

or 3700Watt

 

my brain can't think and someone I know is asking me....

As already said, the power factor pf has to be taken into account. It's all to do with the way alternating current works.

You multiply the kva x pf to give kwatts

It is a number between 0 and 1.0. (it can lag as is usual, but can lead as well)

Typically a figure of 0.8 is about right and can be used with confidence.

Thus 4.8 kva x 0.8 = 3.84 kw. Or conversely 3.7kw/0.8 = 4.625 kva

On this basis the 4.8kva generator is marginally larger.

They are more or less the same size - if you juggle the value of the pf to see what effect it has - try 0.87797 for fun

In practice the actual pf will depend on the type of load connected to the generator.