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3kw generator

Karl

By Karl
in Boat Equipment

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WotEver Veteran II

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Posted
Posted
2 hours ago, cuthound said:

Result 103dBA with one running and 106dBA with both running.

Indeed. As I wrote...

On 29/12/2019 at 11:53, WotEver said:

Decibel measurement is a complex subject, often mis-quoted, and differs whether referring to subjective loudness, SPL, or power. 

 

1 hour ago, markeymark said:

saves 3amps/hr as well.

I wonder how many volts it saves...

  • Haha 1
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IanD Veteran II

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Posted
Posted
2 hours ago, cuthound said:

 

I once fitted two 1000kVA generators into a basement power room. They were two metres apart.

 

I measured the sound pressure level one meter from each generator with a calibrated meter.

 

Result 103dBA with one running and 106dBA with both running.

 

However with ear defenders on, the noise level I perceived didn't sound much louder than with one running.

 

I suspect that if I had installed a third generator the SPL would have been 109dBA with three running.

 

 

Speaking as someone who (among other things) runs PA systems with music and instruments that some would class as noise, a 3dB difference in level is certainly noticeable but not enough to turn an acceptable noise level into an unacceptable one. 6dB will probably make this change in perception, 10dB certainly will.

 

Bear in mind that A weighting (usually used for specifying noise levels) is intended to roughly compensate for the response of the ear to different frequencies so that different sources have the same "apparent volume" if they have the same dBA level. However annoyance and volume aren't the same thing, A weighting rolls off low frequency noise (which the ear is less sensitive to) like exhaust drone but these are the most likely to penetrate inside adjacent boats -- this is the same problem as thumping bass as a noise nusiance in houses.

 

The quietest marine generators are in the 52dBA-55dBA region (measured at 7m) -- a 65dBA generator is in no way "quiet" no matter what the blurb says...

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cuthound Veteran II

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Posted
Posted
9 minutes ago, IanD said:

Speaking as someone who (among other things) runs PA systems with music and instruments that some would class as noise, a 3dB difference in level is certainly noticeable but not enough to turn an acceptable noise level into an unacceptable one. 6dB will probably make this change in perception, 10dB certainly will.

 

Bear in mind that A weighting (usually used for specifying noise levels) is intended to roughly compensate for the response of the ear to different frequencies so that different sources have the same "apparent volume" if they have the same dBA level. However annoyance and volume aren't the same thing, A weighting rolls off low frequency noise (which the ear is less sensitive to) like exhaust drone but these are the most likely to penetrate inside adjacent boats -- this is the same problem as thumping bass as a noise nusiance in houses.

 

The quietest marine generators are in the 52dBA-55dBA region (measured at 7m) -- a 65dBA generator is in no way "quiet" no matter what the blurb says...

 

Indeed, a common specification for a standby generator in an urban environment would be 65dBA at one metre from noise breakout points (exhaust outlets and air inlet and oulet louvres) and 50dbA at the site perimetes, measured at 03:00 to minimise background noise.

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WotEver Veteran II

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Posted
Posted
20 minutes ago, Alan de Enfield said:

My little Honda EX650 is apparently 54Db

Is that 54dBA? At what distance?

 

Both of those questions make the figure relevant. Without those answers you could just as easily say it’s 1dB; just move further away. 

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WotEver Veteran II

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Posted
Posted (edited)


Just to make life more interesting, the EU now mandate manufacturers and sellers of any noise-creating equipment to use LWA (sound power) instead of dBA (sound pressure) to determine how noisy the equipment is. 
 

They’ve even produced a handy 78 page document all about it...

https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2000:162:0001:0078:EN:PDF

 

 

Edited by WotEver
Fixed the subscript
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Alan de Enfield Veteran II

Alan de Enfield

Posted
Posted (edited)
13 minutes ago, WotEver said:

Is that 54dBA? At what distance?

 

Both of those questions make the figure relevant. Without those answers you could just as easily say it’s 1dB; just move further away. 

I do realise that but its an '80s Genny and I cannot find the full specs for it.

 

Its really, really quiet, I've been stood next to it and not realised its running.

 

 

Edit - Found it :

 

Manual states : 52 dB (A) at 7m.

 

 

 

Screenshot (44).png

Edited by Alan de Enfield
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MtB Veteran II

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Posted
Posted
35 minutes ago, CompairHolman said:

They just started their engine about 10 mins ago so they don't give a toss.

 

I reckon they must have been reading that thread about it. Y'know, the one where you maintained CRT were acting ultra vires putting the genny curfew into the T&Cs.... :giggles:

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