automatic inverter humm

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automatic inverter humm

November 14, 2017, 08:06:41 pm

I have 2 Power 50 Transfer, automatic inverters, shoreline transfer switches that hum/buzz when I am hooked up to shore power. is this normal?? they are under the foot of the bed and I can hear it humming at nite when I sleep......

Re: automatic inverter humm

Reply #1 – November 14, 2017, 08:08:17 pm

Keith,
I have a different brand and I get a hum also.
John M.

Re: automatic inverter humm

Reply #2 – November 14, 2017, 08:09:57 pm

thanks john, it's kind of annoying..

Re: automatic inverter humm

Reply #3 – November 14, 2017, 08:10:47 pm

Yes it is.

Re: automatic inverter humm

Reply #4 – November 15, 2017, 08:52:55 am

That hum can be caused by the AC coil that is energized. This coil holds in your contacts that determine whether you are on shore power or generator. The hum can also be caused from dirty contacts but most likely it is the coil. You can clean the contacts if you are comfortable with tinkering and you disconnect all your power sources. They make is a coil/contact that is DC that can replace the AC coil you have now. To change out this coil you will need to have more advanced electrical skills. Some here have went this route and have given good reviews.

Pamela & Mike

Re: automatic inverter humm

Reply #5 – November 15, 2017, 09:12:29 am

First--a disclaimer: I am not a sound engineer or an expert in sound attenuation.
Is it possible sound is being transmitted thru the wood the unit is mounted on? Better isolation of the unit possible?
What about lining the compartment with sound attenuating material? Bottom of the bed?
What about gluing or riveting heavier gauge metal and/or sound deadening media onto the unit housing?
When I designed metalworking machines I found thin sheet metal guards really reverberated from the noise inside the enclosure. I used two gauge heavier sheet metal and really cut the sound.
I put carpet padding on top of the engine compartment and under the carpets in our 1957 Beetle and the difference in sound was measurable!
Again, just some backyard Rube Goldberg fixes if you are not wanting to replace/rework your existing setup.

Re: automatic inverter humm

Reply #6 – November 15, 2017, 10:23:52 am

I had the same problem and it was annoying to the point that we would flip off the outside circuit breakers. You can easily isolate the noise using the modified stethoscope sold in hardware stores, but it is likely the ATS (automatic transfer switch). I bought the current version of the 50A ATS from Edco and replaced it in about 1/2 hour. This solved the problem; it is now very quiet in our bedroom. Now if I could find a solution to my tinnitus.

Re: automatic inverter humm

Reply #7 – November 15, 2017, 10:54:20 am

I live in a Jayco gooseneck with a converter that hums constantly. Only salvation is that I can't hear it from the bedroom. My old Travco used to interfere with sleep until I moved that power supply to the back of the fridge compartment and set it on a hunk of foam rubber. I think the vibration noise was coming from xfmr laminations?

Jim

Re: automatic inverter humm

Reply #8 – November 15, 2017, 01:56:50 pm

Quote from: hdff – November 14, 2017, 08:06:41 pm

I have 2 Power 50 Transfer, automatic inverters, shoreline transfer switches that hum/buzz when I am hooked up to shore power. is this normal?? they are under the foot of the bed and I can hear it humming at nite when I sleep......

Bought this:

50 AMP RV SHORELINE TO GENERATOR AUTOMATIC TRANSFER SWITCH LPT50BRD | eBay

Has good reviews. No more hum. Sold the old one for $125.00 on Ebay. Guy asked if it hum. I said yes, he bought it anyway.

15-25 minutes to install. Been in 6 months. Great sleep with no hum at all. Wife happy too!

Re: automatic inverter humm

Reply #9 – November 15, 2017, 08:38:08 pm

newbie question...... I have 2 is that normal??

Re: automatic inverter humm

Reply #10 – November 15, 2017, 08:52:06 pm

Quote from: hdff – November 15, 2017, 08:38:08 pm

newbie question...... I have 2 is that normal??

On your coach Yes.

One is either generator or shore power
The other is shore/generator or inverter

This info should be shown on you A-2700 print

Pamela & Mike

Re: automatic inverter humm

Reply #11 – November 15, 2017, 09:33:17 pm

Quote from: hdff – November 15, 2017, 08:38:08 pm

newbie question...... I have 2 is that normal??

Yes. Our 2003 U320 also has two.

Re: automatic inverter humm

Reply #12 – November 15, 2017, 09:47:25 pm

Quote from: AC7880 – November 15, 2017, 09:33:17 pm

Yes. Our 2003 U320 also has two.

So does our 1997:
1 inverter
1 shore/gen set
Foretravel chose to NOT use internal transfer switch in the inverter. Good call

Re: automatic inverter humm

Reply #13 – November 16, 2017, 02:49:36 am

Quote from: gracerace – November 15, 2017, 09:47:25 pm

So does our 1997:
1 inverter
1 shore/gen set
Foretravel chose to NOT use internal transfer switch in the inverter. Good call

Why was this good of Foretravel to not use the internal crossover in the inverter/converter? When you changed out your transfer switch to get rid of the hum, did you change the one on the left or right facing the rear of the rv? I installed a new Xantrex pure sinewave inverter/charger and all works fine other that the hum. I too have turned off the breaker to the inverter at night to get away from the hum.

Re: automatic inverter humm

Reply #14 – November 16, 2017, 04:02:39 am

Fortunately my tinnitus makes it inaudible.

Re: automatic inverter humm

Reply #15 – November 16, 2017, 04:08:46 am

Quote from: gracerace – November 15, 2017, 09:47:25 pm

So does our 1997:
1 inverter
1 shore/gen set
Foretravel chose to NOT use internal transfer switch in the inverter. Good call

I'll have to look again but I think the 2 are the same thing. they are on top of each other at the foot of the bed, if you look closely you can see the top of the silver sticker under the one pictured. so these are responsible for controlling which power is used, generator or shore power... I guess that's another newbie question

Re: automatic inverter humm

Reply #16 – November 16, 2017, 09:26:34 am

Quote from: hdff – November 15, 2017, 08:38:08 pm

newbie question...... I have 2 is that normal??

Howdy hdff,
This print will show the two ATSs.
Dave A

Re: automatic inverter humm

Reply #17 – November 16, 2017, 02:43:11 pm

On my 1996 U320 the automatic selector switch inside the 2.5KW inverter/charger was rated for 15 amps (1.8KW), while the automatic selector switch installed by Foretravel was rated at 50 amps (6.0KW). The breakers in the inverter sub-panel could demand close to 50 amps, making the 15 amp selector switch in the inverter/charger insufficient.

The buzzzz from the OEM automatic selector switches were far too loud for me, so I replaced them with manual, hot switchable, 65 amp switches. The additional benefit for boon docking is that automatic switches use watts while manual ones never consume power.

Re: automatic inverter humm

Reply #18 – November 16, 2017, 02:54:21 pm

Wyatt,
Do you have any info on the switches you used? Also, did you have to install 2 switches, one for each transfer switch?
John M.

Re: automatic inverter humm

Reply #19 – November 16, 2017, 04:34:22 pm

I made what some may consider to be radical modifications to the 120 A/C wiring in my 1996 U320 in 2011. I am very satisfied with how well the A/C now works.

I could not understand why Foretravel used a inverter subpanel, when the two auto switch boxes could have been wired to povide ac power to just one ac panel. I removed the subpanel and rewired all circuits into the main panel.

The OEM power cord and wiring from the utility bay and wiring from the generator includes one neutral wire but two hot wires (a RED wire and a Black wire).
I divided the neutral bar in the main panel into two neutral bars, one for "red hot" circuits and one for "black hot" circuits. The panel was actually built for that so it was an easy change.
I seperated the neutral wires for the red hot circuits from the neutral wires for the black hot circuits.

I installed two manual, ac 65 amp (hot switchable) switches in the top of the main panel (one for the RED hot supply and one for the BLACK hot supply). These switches cost more dollars then the auto switches, so this was not a cost saving change. I also painted the front of the ac panel with red and black paint to clearly indicated which breakers are supplied from the "red hot" and which are supplied from the "black hot". The "black hot" ac switch is double poled and selects shore or genset. The "red hot" switch is triple poled and selects shore, genset, or inverter. Now the power source is clearly evident at a glance, the switches are SILENT, do not consume power, and allow for hot switching between power sources.

I will search for information on the switches I used, but they are rotary and compact, and required extending the OEM wiring from the closet to the foot of the bed.

Re: automatic inverter humm

Reply #20 – November 16, 2017, 05:17:17 pm

The Blue Sea Systems 9019 switch has sufficient capacity to replace either ATS.

AC Rotary Switch - OFF + 2 Positions 240V AC 65A - Blue Sea Systems

I have been running one of these for 2.5 years - works perfectly.

What did you do to your coach today IV

Here is one store with the 9019 on "sale". Posted prices vary, and change often. Do a Google search for best price if you are interested.

Blue Sea Systems 9019 AC Selector Switch, AC 240VAC 63A OFF +2

Re: automatic inverter humm

Reply #21 – November 17, 2017, 04:17:01 pm

has anyone tried the newmar switch $125

Newmar SS 7.5 Transfer Switch - Newmar SSSWITCH75 - AC Circuit Panels -...

Re: automatic inverter humm

Reply #22 – November 17, 2017, 10:26:48 pm

Quote from: Jack Lewis – November 16, 2017, 02:49:36 am

Why was this good of Foretravel to not use the internal crossover in the inverter/converter? When you changed out your transfer switch to get rid of the hum, did you change the one on the left or right facing the rear of the rv? I installed a new Xantrex pure sinewave inverter/charger and all works fine other that the hum. I too have turned off the breaker to the inverter at night to get away from the hum.

I see Wyatt answered your question about why FT used a stand alone transfer switch, instead of the one inside the inverter.
I switched out the upper transfer switch, that is for shore/gen. It really hummed when plugged in.
The lower one hums some, when the inverter is on, but I don't leave it on at night. I installed a small 300 watt inverter in the front overhead for the satellite recorder. Also a small 100 watt one for the rear TV. We leave the 300 watt one on 24/7. Even when dry camping. We also have 600 watts solar, so never an issue.We turn the small 100 watt one off, when not watching TV in the bedroom. Rarely use the big inverter.
Biggest improvement I made, changing out the transfer switch. Cheap too.Hope this help
Chris

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