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Old 13-11-2010, 02:56   #1
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How Loud Is a Charles Isolation Transformer

I plan to install a Charles 93-ISOG2/8-A Isolation Transformer on my 30 foot sailboat but am concerned about how much noise it may make. The best boat placement for it is under the quarter berth, a few inches beneath my pillow.

The installation manual states:

"the IsoG2 will produce a noticeable “hum” when it is energized, although not nearly as loud as nonencapsulated
transformers"


I tend to be fairly sensitive to artificial noises. At home I got rid of my AC clock radios years ago because buzz next to my head from their little internal transformers was annoying.

Do you have one of these Charles transformers or have you been on a boat with one running? How loud is the hum? Is the volume proportionate to power draw? Do you have tips for sound proofing?
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Old 13-11-2010, 05:49   #2
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Loud enough for us to turn off the shore power whilst in bed.

We have two (for each side of the twin 30A supply) and one is noticably louder than the other.

I spoke to Charles and they said they'd take it back, but I couldn't be bothered disconnecting and returning this huge lump.

Duncan
S/V TALISA
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Old 13-11-2010, 06:07   #3
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I don't know the Charles one, but we have a Victron, and it is annoyingly noisy when it is under load. Unfortunately my isolation transformer is also near my head at night, albeit on the other side of a structural bulkhead in the laz.

Fortunately, it is quiet when the lights go out at night and consumers are switched off and the batteries are up. In the worst case you can just switch off the shorepower as DE does.

Far more annoying than noise is the hard, strict limit on current which means it trips frequently. I had just assumed (wrongly) that it would be somewhat forgiving of brief overloads, as the rest of the shore power system is, but nope, 0.1 amp more than the rated capacity for 1/10 of a second and wham! Lights out!
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Old 13-11-2010, 15:16   #4
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Your experiences are not encouraging. I was really excited about using an IT for improved safety and reducing galvanic corrosion. But a pronounced hum is a no-go.

The best I could do on my boat would be installing the IT in the starboard lazarette. That would place it two bulkheads and 6-10 feet away from my head. That location also would provide sufficient air space around the unit for ventilation.

I wonder if the noise has to do with the IT being mounted to a solid, resonant surface. Drawing on an analog I know well, a music tuning fork makes a soft hum that is greatly amplified by touching the base of the fork to a box or surface like a table top or wood floor. Would isolating the transformer with rubber mounts prevent transmitting vibrations through the hull and reduce noise?
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Old 13-11-2010, 16:09   #5
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My 30A Charles Transformer is definately doing the humming all by itself !

As per Dockhead's experience, when they are lightly loaded, they tend to make less noise.

When I have the A/C running, I can't hear the noise above the din from the compressor, but when I have just the one transformer active and I'm juicing up the batteries a lot, you can definatley hear it.

I can just about put up with it as I know it's doing the boat some good (like charging the batteries), but the Admiral kicks up about it and wants it off if it's making too much noise.

Mind you, she makes me turn off the wind generator too as soon as she gets into bed and I keep thinking '8 hours of free juice going to waste'.

Duncan
S/V TALISA
Fernandina Beach
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Old 13-11-2010, 16:53   #6
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Duncan,

After being married for over 40 years, I can say definitely that if you insisted on keeping the wind generator running despite her pleadings, you would have something else free that would be going to waste. A sex life !
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