Inverter relay buzz

NYSail

NYSail

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Jan 6, 2006
3,060
Beneteau 423 Mt. Sinai, NY
Hello all,

So I have a 3000w inverter that I just started to use as I am now working from the boat..... printer and charging lap top. I never used the inverter before however it always hums loud from behind the electrical panel. Inverter works fine. So today I opened up the panel and there is a relay prior to the ac panel that is making all the noise. I looked it up and only $35. Just want advise if this is what happens when a relay starts to go bad or is it sign of something else?

Thanks!
Greg
 

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LloydB

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Jan 15, 2006
819
Macgregor 22 Silverton
Your relay sounds like it's operating normally. However. It is operating normally in a unusual manner, what does it do? To rephrase that, what specific thing does it turn off or on when it operates. That does not look normal to me.
 
NYSail

NYSail

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Jan 6, 2006
3,060
Beneteau 423 Mt. Sinai, NY
Pardon my ignorance but Not sure what you mean “what does it turn off/on”. When I activate or turn on the inverter there is no hum. However as soon as I switch the ac panel from shore to ship the relay closes and it immediately hums without a load. When I switch on ac outlets with a load from printer or whatever no change...... same hum.

Thanks
Greg
 
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LloydB

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Jan 15, 2006
819
Macgregor 22 Silverton
The movie you posted that I opened up and watched the relay operated 2 times and then it ended. I assumed that it was turning on and off constantly like a turn signal and that was what you called the hum. some relays will make a humming noise as they turn off and on . in short I couldn't hear the humming for the clicking. Sorry old ears.
 
SycloneDriver

SycloneDriver

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Jul 23, 2009
857
Beneteau 31 Oceanis Grand Lake, Oklahoma
I wonder if that relay is providing the neutral/ground bond?
It's not that expensive. If it bothers you replace it.
What type of inverter? If it's a modified sine wave, it might cause the buzz.
 
NYSail

NYSail

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Jan 6, 2006
3,060
Beneteau 423 Mt. Sinai, NY
It’s a Xantrex 3000w 2005. It is connected to a grounding plate on hull. Video was me turning a/c power on and off just to show humming
 
SycloneDriver

SycloneDriver

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Jul 23, 2009
857
Beneteau 31 Oceanis Grand Lake, Oklahoma
NYSail said:
It’s a Xantrex 3000w 2005. It is connected to a grounding plate on hull. Video was me turning a/c power on and off just to show humming
Click to expand
Is 2005 the year it was made? Really need more info. How about some pictures of the inverter & the relay.

The neutral and the ground still need bonded even with a ground plate.
 
NYSail

NYSail

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Jan 6, 2006
3,060
Beneteau 423 Mt. Sinai, NY
Video above of relay. Inverter came with the boat in 2005. From factory......CC4DA970-D91C-4DC4-AE54-3C89568CF599.jpegB585EE30-7098-4495-A17A-C5D9190F6AE2.jpeg
 
B

Benny17441

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May 24, 2004
7,131
CC 30 South Florida
Sometimes dirt particles get into the relays case and prevents the armatures mechanism from sealing up tight contacts. This would require the coils to be drawing additional power to maintain function and will eventually lead to failure. This is just one of the causes and cannot guarantee it is your problem but if that relay is old you could not go wrong by replacing it.
 
NYSail

NYSail

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Jan 6, 2006
3,060
Beneteau 423 Mt. Sinai, NY
Thanks Benny! Think I will order one. Then next weekend take all connections apart from relay to ac panel and clean them. 15 years old.....
 
NYSail

NYSail

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Jan 6, 2006
3,060
Beneteau 423 Mt. Sinai, NY
I am here asking because I don’t know..... just following the wire set up. Inverter is wired up to power entire ac systems in boat ( all outlets, microwave, Etc) not just one outlet. Inverter wires to relay to ac panel.

Thanks
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
22,770
Catalina 34 224 Maple Bay, BC, Canada
Could it be that what you are describing as a relay is actually the automatic transfer switch between shorepower and the inverter so that both can never be on at the same time? Does your inverter have an automatic transfer switch inside it? How is it wired? Does the shorepower go to the inverter "box" or to the relay first?
 
NYSail

NYSail

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Jan 6, 2006
3,060
Beneteau 423 Mt. Sinai, NY
On my ac panel there is a breaker for shore power or ship power (inverter / generator). What was in the video is a relay..... It starts to hum as soon as I switch ship ac power at the panel And stops when I turn ac panel off.

1B307804-3BB9-494D-A5D5-315B4EC89D62.jpeg
 
NYSail

NYSail

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Jan 6, 2006
3,060
Beneteau 423 Mt. Sinai, NY
Don’t believe shore power goes through this relay..... Shore power goes straight to panel.

Thanks
 
walt

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
When I activate or turn on the inverter there is no hum. However as soon as I switch the ac panel from shore to ship the relay closes and it immediately hums without a load. When I switch on ac outlets with a load from printer or whatever no change...... same hum.
Click to expand
Could it be that what you are describing as a relay is actually the automatic transfer switch between shorepower and the inverter so that both can never be on at the same time?
Click to expand
Likely.. and he said the inverter works fine by itself.

I listened to that video.. my "calibrated ears ???" think that is a 60 hz buzz.. If the relay coil is powered by AC and it mechanically starts to degrade, the coil could buzz like that. I doubt it hurts anything but would be annoying. If the relay coil is powered by DC, it wont buzz unless the drive circuit was oscillating (I dont think this is the case since it sure sounds like 60 hz).

Relay is cheap and sounds like you can find a replacement.. I would just replace it. FYI, does the relay buzz in shore power position.. or does is buzz in "ship"? If its buzzing in ship, you are using the boats batteries to power that relay ... no big deal if you have tons of power available but.. relays use a bit of power to operate the coil (like several watts) which might be important in a lower power system.. If it buzzing is in shore power mode, can we assume that the relay drive power is coming from shore power so no big deal at all..

Edit.. re read the OP statement and he said the relay buzzes in ship mode.. So likely you are powering the relay somehow from your batteries.

A bigger job.. but dont those ship or shore power switches come in mechanical only versions.. Ie, no relay at all to either use power or make noise?
 
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Bob S

Bob S

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Sep 27, 2007
1,771
Beneteau 393 New Bedford, MA
I've been following this thread. I have the same inverter but haven't used it. The AC panel has a mechanical bracket which locks you our of shore power in order to switch to the inverter. You must also have a remote switch? I think this acts the same as the on off switch on the inverter itself but if yours is like mine it's not too accessible. I haveen't traced the wiring so I'm hesitant in using it. I'm sure it's a handy tool to have but at the same time I fear for my batteries if my wife knew what it can do. Blow dryers, blenders, toaster and on and on! I have a Honda for that.


Switches.PNG
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
22,770
Catalina 34 224 Maple Bay, BC, Canada
NYSail said:
Don’t believe shore power goes through this relay..... Shore power goes straight to panel.
Click to expand
If the shorepower goes to the panel, how does the inverter feed the AC system on your boat? That's why I asked what the relay is for and what purpose it serves.
 
NYSail

NYSail

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Jan 6, 2006
3,060
Beneteau 423 Mt. Sinai, NY
Yes... I do have the RED switch which is a break between batteries and inverter. Then I have the remote switch which will turn it on..... All good to this point with no buzz. However as soon as I slide the mechanical bracket and turn on the Ship AC Power..... the relay closes and the hum begins. Now this is a thought, could the inverter in-fact be wired directly to the ac panel then go to the relay? It is tight behind the panel and I did not open the rear cover to the ac panel to trace those wires that lead from the relay to the panel. Guess I need to investigate. But either way, a 15 year old relay may have a loose coil which might cause a hum? I am going to buy the new one and in mean time will open up everything just to really know how its wired. I just assumed it was going from inverter to relay to panel.....

Walt... no there is no humming when the shore power is on..... nice and quiet. btw amazing ears!!

btw Bob, I always was thinking of pulling the inverter out as everything I had was dc, however I am moving my office capabilities to be able to work completely from the boat and the inverter is great for this (ie printer and charging lap-top). Power usage is not that steep..... so I am happily impressed so far.

As Always I want to thank everyone who has chimed in on this..... Always a great education!

THANKS!

Greg
 
B

Benny17441

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May 24, 2004
7,131
CC 30 South Florida
Bob S said:
I fear for my batteries if my wife knew what it can do. Blow dryers, blenders, toaster and on and on! I have a Honda for that.
Click to expand
I hear you, but think of the plusses, we have caught many of a Sunday football games on TV while underway, heated a cup coffee with the microwave, ran our laptop, recharge electronics, and run X-Mas lights. We obviously have to be conscious of the Amps spent but even a short use of the microwave oven will not break the bank. We also carry a portable Honda generator but sometimes it is not worth the effort to set up for what little power is to be used and we usually do not like to run it with the boat underway.
 
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