Transfer switch buzzing

I used to have a buzz occasionally that I thought was the ATS, turned out it was the converter nearby. There was a set of old batteries I was hanging onto trying to squeeze as much use out of them that I could and when they were inadvertently depleted like during a long road trip with some dry camping, when I'd plug into shore power, the converter would buzz because of the heavy draw caused by those batteries as they charged up. Once they approached full charge, the buzz would fade.

So check to be sure it's your ATS buzzing and not your converter.

Transfer switches buzz because the two metal armatures are not 'sealing up' tight together. Dirt will find it's way in and AC relays do not like anything between the two surfaces. If an AC relay does not 'seal up', it's coil will draw extra current and a buzzing relay will be much more likely to burn up. If you feel capable, you can take the relay apart and clean the two laminated surfaces. Putting a piece of fine sandpaper on a flat surface and rubbing each armature across it to clean and flatten the surface will help. When the surfaces get really beat up, you'll need a new relay. Just something else that will last much longer if you maintain it by keeping it clean. If it isn't buzzing, it's not getting damaged.

the transfer switch IS a 'relay'

on a 30 amp RV the shore power is normally the selected line and the switch should not be buzzing

the generator is on the open side that closes and makes switch/relay contact after the generator starts

if you don't know anything about electrical
get an RV tech or friend who does, to look at it

Call Randy at Best Converter. Get a new power center with a more modern converter.

The buzz in mine was a relay to prevent the (lousy) converter from frying the starter battery.

Does the transfer switch at different plug ins? Or, are you just hearing the noise where you have it plugged in right now. Voltage and Frequency will have an affect on older transfer boxes and make them hum/buzz. You need to verify that you 120 power is within spec(110 to 128) and the frequency is correct. Are you using any adapter from the shore cord? Doug

It could be many things from low voltage to dirty contacts to a loose wire. If you are not comfortable working with the transfer switch find someone who is.
Basically you take the cover off, clean all of the contacts, and check to make sure all of the wire connections are tight.