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Monaco Wolfy · 04-30-2019, 03:20 PM

I've experienced a loud buzz coming from my transfer box. If I turn the power source off and back on, it usually stops the buzzing. So, after unplugging all power, I started poking around and looking under the box covers to see if anything shows signs of burnt wires. All the wires look good. No melted plastic. I read on this site that the contacts are most likely dirty and need cleaning. In a day or so, I'll pull out the switch and take a closer look. Does anyone know if the contacts are easily accessible for cleaning after taking it out of the box?

While poking around, I noticed a black box under the transfer switch box. The owners manual for the coach says it has a surge protector. Shown in the picture. The black box doesn't say much on it, just what you see. It does say protector, but I don't see the word surge. Anyone know for sure, Is this a surge protector?

Further, there is two boxes. One is the transfer switch, but what is the other one for?

Monaco Wolfy · 04-30-2019, 03:39 PM

Answering one of my questions, I put my cell camera under it. It's a surge protector. Anyone know if it's sufficient?

puttin · 04-30-2019, 03:51 PM

This will tell you a little bit more about the unit. In my opinion I'd get another stand alone from either Progressive or Southwire.

http://psihq.com/tvss/UnitedPower/pdfs/tss.pdf

Rustygold · 04-30-2019, 03:52 PM

Quote:

Originally Posted by Monaco Wolfy

Answering one of my questions, I put my cell camera under it. It's a surge protector. Anyone know if it's sufficient?

Wolfy,
That's what mine looks like. I did need to replace the transfer switch awhile back and the original placement for the surge protector was attached to the backside of the transfer box. When I changed out the switch, I moved the SP to the front side of the box. Now I can see the two green lights, as before I couldn't see anything on the SP.
My transfer switch unit does make a humming noise, but not to the point that it is annoying or too loud.
Hope this helps.

falconman · 04-30-2019, 09:38 PM

The other grey box is for the Aladdin AC interface, volts/ amps, etc.

K7JV · 05-01-2019, 07:22 AM

It looks like you've identified everything, for the most part. As for cleaning the contacts on the two relays, I would be surprised if they need maintenance. They are designed to do their job thousands of times at their rated loads without failure. One of those relays is in the incoming line from your on-board generator, and the other is in the incoming line from your shore power. They are in an either/or configuration and are most likely controlled so that your on-board generator is the preferred source. Only one is energize at any one time.

Again, they shouldn't require maintenance. Those devices, when energized, have a 120 cycle hum due to something called magnetostriction. On each half-cycle of the 60 cycle excitation voltage the little iron core in the relay constricts, every so slightly, and relaxes again each time the voltage waveform crosses zero, hence the 120 cycle hum. That is what produces the sound you are hearing. Any parts of the hardware on the device, or very close to it, that might be slightly loose may vibrate a bit, too, seeming to be amplifying the sound. Unless it is excessive, you probably don't have a problem.

Regarding the sufficiency of your surge protection, that depends completely on the job it is asked to perform. Normal utility or coach generated voltage transients will easily be absorbed by most surge protection devices. Also, today's utility standards have come a long way in reducing the frequency, magnitude and duration of surges on our power systems, which is good. A close-in lighting strike? It likely won't protect all of your equipment. But for most of us, the surge protection provided in our coaches is very adequate. If you feel otherwise, there are external devices that are quite good that can be inserted at the power pedestal by you, each time you connect to shore power. They can go from quite small and light to quite heavy and very effective at even controlling low or high voltage supplies.

Monaco Wolfy · 05-01-2019, 10:56 AM

Thanks for all the input. That's what makes this site so great.

I like the idea of not having to deal with securing a Surge protector at the power post. Having it inside the coach makes more sense to me. Does anyone know of a better, modern day, inside protector that might do a better job for low and high voltage?

rgvtexan · 05-01-2019, 12:02 PM

This is the best RV unit. IMHO

https://www.progressiveindustries.net/ems-lchw50

153stars · 05-01-2019, 04:58 PM

Contractors can hum we have these exact ones at work , they are not the quietest . Ill bet there is rust between the laminated metal parts. The whole front part should off with a few screws . don't mix up the contacts they will be somewhat mated to each other from arcing. Sand off rust on mating faces with 120 grit. I would mess with contacts unless they are real bad maybe a couple swipes with 400grit if at all. Blow out or use contact cleaner.