Re: [Amel Yacht Owners] AC Panel Green Light

Andrew & Kate Lamb

A little bit off googling confirms that:


“The two factors are related as per the following formula –

Generator Frequency (f) = Number of revolutions per minute of the engine (N) * Number of magnetic poles (P) / 120

Conversely, P = 120*f/N


As per the above formulae, a 2-pole generator producing an output frequency of 60 Hz has an engine speed of 3,600 rpm. To change the output frequency to 50 Hz for the same generator configuration, the engine speed needs to be reduced to 3,000 rpm. Similarly, for a 4-pole generator, an engine speed of 1,800 rpm produces output of 60 Hz. Reducing the engine speed to 1,500 rpm yields an output of 50 Hz.”



Ronpische SM472



From: "amelyachtowners@..." <amelyachtowners@...> on behalf of "amelyachtowners@..." <amelyachtowners@...>
Reply-To: "amelyachtowners@..." <amelyachtowners@...>
Date: Tuesday, 27 September 2016 at 10:00
To: "amelyachtowners@..." <amelyachtowners@...>
Subject: Re: [Amel Yacht Owners] AC Panel Green Light



Hi Peter,


Think about it a bit; the mathematical relationship is wrong if we are to use your suggestion.


ABSOLUTELY, 50 Hz is 1500 rpm.  60 Hz is 1800 rpm.


Fair winds to you my friend!


Jean-Pierre Germain

Eleuthera, SM 007, Madeira



On 26 Sep 2016, at 23:00, 'hanspeter.baettig@...' hanspeter.baettig@... [amelyachtowners] <amelyachtowners@...> wrote:




hi Bill Kenney

your are wrong. 50 hz at 1800 rpm

60 hz at 1500 rpm

read the manual

kind regards


Tamango 2


Von meinem iPhone gesendet

Am 26.09.2016 um 16:42 schrieb Bill Kinney greatketch@... [amelyachtowners] <amelyachtowners@...>:


Hello  All,


On these generators the rotational speed controls the FREQUENCY of the power NOT the voltage.  A 50 Hz generator should run at 1500 RPM, for 60 Hz they should run at 1800 RPM.  If your frequency is right, your speed is right.  If you voltage is wrong, something else needs fixing.



Bill Kinney

SM #160, Harmonie

Solomons, MD, Chesapeake Bay, USA

“Ships and men rot in port."





On Sep 26, 2016, at 06:06, svperegrinus@... [amelyachtowners] <amelyachtowners@...> wrote:


Hello Alexandre,


Ours puts out 219V with no load, 217V with max load, and 218V with half load.  It's been that way for at least 3 years, since I started looking at this measurement.


I asked the only Onan-recommended, Onan certified dealer, in this part of the world why I am not getting 230V on a 230V boat, and whether he should adjust it.


He bent over, took a pic of the genset spec plate and showed me his phone: the genset spec reads "220V".  He said we should leave it alone.


Now with this thread I a am not so sure.  


When he comes by tomorrow, I'll ask him to check the RPMs.  Should be 1800, uh?





SM2K No. 350

Marina d'Arechi, Salerno







Jean-Pierre Germain,

+44 7551 211 511


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