I have just taken delivery of a new 386 and there is a very loud buzzing sound coming from the dock power isolation transformer. The dealer tells me it is because there is current in the ground wire but the marina checked it out (supposedly) and said everything is fine on their end. Has anyone else experienced a similar situation? thanks
- Status
Probably just
loose laminates in the transformer. Move your A/C connection to a different transformer and see if it still hums loudly. There will always be some humming coming from a transformer.
loose laminates in the transformer. Move your A/C connection to a different transformer and see if it still hums loudly. There will always be some humming coming from a transformer.
Hum / buzz from x-former
My isolation transformer is mounted very solidly to a bulkhead, and it hums more when it is unloaded. On a previous boat, it wasn't mounted to something so solid, and the humming was almost not noticed. The comment about the ground wire is curious. The ground wire is not hooked to anything inside the boat(except perhaps the neutral). It is used as a case ground to the transformer itself, but goes nowhere other than that. Is yours hooked up correctly?
My isolation transformer is mounted very solidly to a bulkhead, and it hums more when it is unloaded. On a previous boat, it wasn't mounted to something so solid, and the humming was almost not noticed. The comment about the ground wire is curious. The ground wire is not hooked to anything inside the boat(except perhaps the neutral). It is used as a case ground to the transformer itself, but goes nowhere other than that. Is yours hooked up correctly?
Me too
I had the same problem on delivery of my 2004 Passage 456. Dealer replaced both, but they are still a bit noisey. I haven't looked, but someone mentioned the plates inside might be loose and the bolts could be tightened. Good luck]Dave s/v Quiet Wings
I had the same problem on delivery of my 2004 Passage 456. Dealer replaced both, but they are still a bit noisey. I haven't looked, but someone mentioned the plates inside might be loose and the bolts could be tightened. Good luck]Dave s/v Quiet Wings
An update on the isolation transformer
The lastest is that it still hums loudly when hooked up to the dock power at the dealer so it must be in the unit. I appreciate the comments concerning the mounting and perhaps a softer mount would be worth a try. At this point and since its a new unit and still under warranty, I think the easiest thing (for me) is to swap the unit out and see what happens then.
The lastest is that it still hums loudly when hooked up to the dock power at the dealer so it must be in the unit. I appreciate the comments concerning the mounting and perhaps a softer mount would be worth a try. At this point and since its a new unit and still under warranty, I think the easiest thing (for me) is to swap the unit out and see what happens then.
Transformer noise
I have the same problem on my '04 Hunter 36. The issue, in my opinion, is the location of the transformer and the mounting method used. If the core laminations are loose the noise would more than likely rattle your teeth or at least be heard at the end of the dock. Hunter has "hard" mounted the transformer on a vertical plane in the transom locker to the same bulkhead that forms the back wall of the aft birth. The normal soft hum you get when a transformer is energized is, I suspect, resonating on the bulkhead and being amplified in the locker space to become an irritating loud noise when trying to get some sleep. I am working with my dealer to resolve the problem by experimenting with installing softer mounts to isolate and deaden the noise, remount the transformer on a horizontal plane, relocate the transformer, or some combination of these. Good luck, Bob Bearce s/v Für Elise
I have the same problem on my '04 Hunter 36. The issue, in my opinion, is the location of the transformer and the mounting method used. If the core laminations are loose the noise would more than likely rattle your teeth or at least be heard at the end of the dock. Hunter has "hard" mounted the transformer on a vertical plane in the transom locker to the same bulkhead that forms the back wall of the aft birth. The normal soft hum you get when a transformer is energized is, I suspect, resonating on the bulkhead and being amplified in the locker space to become an irritating loud noise when trying to get some sleep. I am working with my dealer to resolve the problem by experimenting with installing softer mounts to isolate and deaden the noise, remount the transformer on a horizontal plane, relocate the transformer, or some combination of these. Good luck, Bob Bearce s/v Für Elise
Hum in Transformer
I also have a loud hum in the isolation transformer. My dealer replaced the transformer to no significant avail. If any one has any ideas of how to fix this, I, for one, am interested. It's loud enough in the back berth to keep you awake.
I also have a loud hum in the isolation transformer. My dealer replaced the transformer to no significant avail. If any one has any ideas of how to fix this, I, for one, am interested. It's loud enough in the back berth to keep you awake.
Isolation Transformer Hum
Mike (& others who replied), The basic humming comes from the 'Core' laminations vibrating due to a poor varnish impregnation. They were probably varnish dipped (if that) rather than vacuum impregnated. If you can remove the case (with ALL AC power disconnected) and get to the core laminations, you could recoat the core'Stack' with varnish. If it seems to soak in, then recoat again. After it drys, reattach the case/cover and remount. Using rubber bushings to mechanically isolate the transformer from the bulkhead would reduce the audible sound as someone has already suggested. The comment about 'current in the ground wire' causing it is just babbling BS for somebody who hasn't got a clue what they'er talking about. You proved yhat by moving the shorepower to another location. Dick Carey (Former Transformer Design Engineer) S/V Puffin 1990 H-33.5
Mike (& others who replied), The basic humming comes from the 'Core' laminations vibrating due to a poor varnish impregnation. They were probably varnish dipped (if that) rather than vacuum impregnated. If you can remove the case (with ALL AC power disconnected) and get to the core laminations, you could recoat the core'Stack' with varnish. If it seems to soak in, then recoat again. After it drys, reattach the case/cover and remount. Using rubber bushings to mechanically isolate the transformer from the bulkhead would reduce the audible sound as someone has already suggested. The comment about 'current in the ground wire' causing it is just babbling BS for somebody who hasn't got a clue what they'er talking about. You proved yhat by moving the shorepower to another location. Dick Carey (Former Transformer Design Engineer) S/V Puffin 1990 H-33.5
Hunter replaced mine
We took delivery of our 2004 306 in September. Within weeks the hum from the transformer was so load that it was keeping people on other nearby boats awake at night. The transformer hum would be low (acceptable) when shore power was first connected, but would increase to a very load hum within 10 minutes. Hunter told us that there possibly had been a manufactures defect in some transformers. They had one still at the factory that was doing the same thing. They replaced the transformer and asked us to send the old transformer back to them for inspection. The new transformer still hums, but it's acceptable.
We took delivery of our 2004 306 in September. Within weeks the hum from the transformer was so load that it was keeping people on other nearby boats awake at night. The transformer hum would be low (acceptable) when shore power was first connected, but would increase to a very load hum within 10 minutes. Hunter told us that there possibly had been a manufactures defect in some transformers. They had one still at the factory that was doing the same thing. They replaced the transformer and asked us to send the old transformer back to them for inspection. The new transformer still hums, but it's acceptable.
Transformer Hum
Dick Carey has got it dead right.its lamination hum.The transformer is defective and the manufacturer should replace it and pay all the freight,at least. This is the oldest transformer problem in the book. Retired transformer designer.
Dick Carey has got it dead right.its lamination hum.The transformer is defective and the manufacturer should replace it and pay all the freight,at least. This is the oldest transformer problem in the book. Retired transformer designer.
Isolation Transformer?
My 290 didn't have one, and the new 33 does have it. Found it mounted, upside down at that, under the port settee next to the water heater. What exactly is the purpose of this thing? I asked the dealer, and surpisingly (or maybe not), they couldn't explain it.
My 290 didn't have one, and the new 33 does have it. Found it mounted, upside down at that, under the port settee next to the water heater. What exactly is the purpose of this thing? I asked the dealer, and surpisingly (or maybe not), they couldn't explain it.
Isolation is the key word.
The Isolation Transformwer does exactly that. It isolates the shore power from actually coming aboard your boat. The ground is also isolated from the boat, and usually the neutral is used onboard as a path to ground. The transformer does not increase or decrease the voltage (usually the reason for a transformer) but just electrically isolates the current and ground. I'm sure there are more technical explanations.
The Isolation Transformwer does exactly that. It isolates the shore power from actually coming aboard your boat. The ground is also isolated from the boat, and usually the neutral is used onboard as a path to ground. The transformer does not increase or decrease the voltage (usually the reason for a transformer) but just electrically isolates the current and ground. I'm sure there are more technical explanations.
Purpose of Isolation transformer
Mike, Greg and others; In addition to the previous excellent responses I wanted to mention that the purpose of the isolation transformer is to prevent stray current corrosion. The transformer blocks the flow of DC (Direct Current) along the ac power wiring from shore power. There is no direct connection except through the transformer which only passes AC (alternating current). Another advantage of having an isolation transformer is that the transformer isolates the boat from the possible reversed polarity of the shore power. The ground is reestablished at the output of the transformer in the boat where the green ground is bonded (connected) to the neutral, the white wire in a 30-amp single-phase shore power system. This is good that isolation transformers are being installed in the new hunters. My h340 came without an isolation transformer or galvanic isolator. I hope this information helps and I hope you get the excess hum problem solved. For those of us who work in the electrical / electronics engineering field this is simple to understand but can be confusing for some.
Mike, Greg and others; In addition to the previous excellent responses I wanted to mention that the purpose of the isolation transformer is to prevent stray current corrosion. The transformer blocks the flow of DC (Direct Current) along the ac power wiring from shore power. There is no direct connection except through the transformer which only passes AC (alternating current). Another advantage of having an isolation transformer is that the transformer isolates the boat from the possible reversed polarity of the shore power. The ground is reestablished at the output of the transformer in the boat where the green ground is bonded (connected) to the neutral, the white wire in a 30-amp single-phase shore power system. This is good that isolation transformers are being installed in the new hunters. My h340 came without an isolation transformer or galvanic isolator. I hope this information helps and I hope you get the excess hum problem solved. For those of us who work in the electrical / electronics engineering field this is simple to understand but can be confusing for some.
The reason it hums is..
Because it doesn't know the words. Sorry, Just couldn't resist. Please don't banish me.
Because it doesn't know the words. Sorry, Just couldn't resist. Please don't banish me.
Transformers
I have just taken del. of a new H41. I have two Isolation transformers and my query is how they are mounted. On the side plate it states to fix them with arrows aligned upwards. Mine are installed on there sides. Anyone know how important it is to have them installed as directed on the unit. These were installed at the factory.
I have just taken del. of a new H41. I have two Isolation transformers and my query is how they are mounted. On the side plate it states to fix them with arrows aligned upwards. Mine are installed on there sides. Anyone know how important it is to have them installed as directed on the unit. These were installed at the factory.
- Status