Is their no-hum tranfer switches out there?

dtcerrato · October 27, 2018, 06:52:25 PM

Since we installed our upgrade 50 amp shore power along with a 50 amp transfer switch - the constant hum of the transfer switch is really getting on the wife's nerves. It's going to have to go weather or not I can find one without the hhhhhhuuuuuummmmm.... Are there transfer switches with DC contactors without the annoying hum? If so can anyone comment on them. That's another $150 clams wasted. Not all our decisions are good ones but we must keep keeping on.

chessie4905 · October 27, 2018, 06:59:49 PM

Can you cover it with a thin sheet lead box? Is the hum noticeable because of rigid mounting? Can you mount it on rubber isolators?

Templar52 · October 27, 2018, 07:10:35 PM

I have the same problem with mine. I tried to isolate with rubber,clean it,nothing work.

chessie4905 · October 27, 2018, 07:12:56 PM

There are some that claim to be silent, but more expensive.

dtcerrato · October 27, 2018, 07:20:56 PM

Tried everything to quiet it down but the hum is still very noticeable. We found a couple of different brands with DC contactors but would really like to hear from someone that has experienced them. Best pricing I found was $165-$175. Only no-hum would make it worth it otherwise we're doing away with the current one. Too annoying.

luvrbus · October 27, 2018, 08:12:19 PM

I have a TRC Surge Guard it makes no noise been installed now going on 3 years and it's still quite

Geoff · October 28, 2018, 05:47:01 AM

If it is new, take it back. If it is out of warranty, open the cover and see which relay is humming (if it has two relays). Once you know that, you can safely remove the box and change out the relay that hums. With the part number off the relay you can look on eBay and get the exact replacement. I had one ATS that didn't start humming for a few years, so I did what I am advising you to do.

sledhead · October 28, 2018, 06:19:09 AM

can't help ya because I replaced the old one that had a hhhhhhhhhhhuuuuuuuuuuuuummmmm with a new one and the instructions said to make sure it was mounted vertically and the old one was mounted on its side so I assumed that was the problem .

NOPE ! after about 6-8 months this one started to hum but it is still
ok ish

https://www.amazon.ca/gp/product/B003VAWNVK/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

this is the one I have now crap unless you like the hum

good luck . if you find one let me know

dave

Jim Blackwood · October 28, 2018, 11:12:03 AM

I'm confused, wouldn't transfer contactors be DC operated? Otherwise if your inverter went down it seems like you wouldn't be able to operate your transfer switch? What am I missing here?

Jim

Geoff · October 28, 2018, 11:47:46 AM

The ATS relays are AC, not DC. When they start to hum you can try cleaning the contracts, of course when it is turned off (added for the nit-pickers).

Jim Blackwood · October 28, 2018, 11:59:28 AM

But why would you ever use AC for that? You always have DC on the bus, and it can't hum unless the contacts are really dirty.

Here's why it doesn't make sense to me. OTR you are on DC and inverter power. No DC, no inverter. When you plug in, until the transfer switch closes you're still on DC and inverter. Again, no DC, no AC. If the bus is completely dead you have no AC to actuate the transfer switch unless you bypass the transfer switch somehow. And if you do that won't your inverter charge the DC circuits? So how does it make any sense at all to use an AC contactor for your transfer switch?

Jim

chessie4905 · October 28, 2018, 12:05:43 PM

If the coach is completely dead, how can dc relays actuate once you plug in till charger turns on to provide enough power to actuate relays. I guess what the default is on the transfer switch depends also.

Jim Blackwood · October 28, 2018, 12:10:35 PM

Yeah, that's right too. Maybe what would make sense is a contactor with a manual operator, those are common enough. Push the button to engage the contactor and power up the system. Should work either way.

Still, an AC contactor just seems backwards to me.

Jim

Jim Blackwood · October 28, 2018, 01:01:22 PM

Maybe it would make sense for the battery charger to be hard wired to the shore line? What would be the down side to that? Maybe an inline breaker or switch so you could isolate it if you want.

I realize these days the highly sophisticated inverter/charger units are very popular and for good reason, and I guess some of the better ones have the transfer relays built in, so not a whole lot you can do with that I guess. I just wonder if maybe separate units don't make a little more sense. In which case any generic industrial contactor of the proper rating would do the job just fine. If you want it to turn off or on automatically under certain conditions it's not that hard to do.

Jim

Geoff · October 28, 2018, 01:46:09 PM

Quote from: Jim Blackwood on October 28, 2018, 11:59:28 AM
But why would you ever use AC for that? You always have DC on the bus, and it can't hum unless the contacts are really dirty.

Here's why it doesn't make sense to me. OTR you are on DC and inverter power. No DC, no inverter. When you plug in, until the transfer switch closes you're still on DC and inverter. Again, no DC, no AC. If the bus is completely dead you have no AC to actuate the transfer switch unless you bypass the transfer switch somehow. And if you do that won't your inverter charge the DC circuits? So how does it make any sense at all to use an AC contactor for your transfer switch?

Jim

I'm not sure how DC relays got into the picture. I've never seen a DC relay in a 30 or 50 amp ATS. They are activated by AC relays that switch when you plug into shore power or start the generator. The inverter can work independently with dedicated 120 outlets, have a pass-through, or be a hybrid.