Is their no-hum tranfer switches out there?

dtcerrato · November 07, 2018, 08:47:17 PM

BW how does one determine how to size a soft start capacitor? Where would it hook in at. The compressor is a 1HP motor. It's wired for 110vac & is convertible to 220vac. It would probably be better on 220vac for the ATS but hate to have to be on 50 amp shore power to run it that's why we like it on 110vac. Gotta check the check valve, wonder if the motor capacitor(s) are getting tired. Damned ATS issue is kicking my butt.

chessie4905 · November 08, 2018, 05:18:56 AM

Check voltage at motor when starting. If you have a clamp meter, check amperage draw when trying to start. Instead of soft start, maybe a booster capacitor kit, if it turns out motor starting capacitors are ok.
Do you have an electric motor repair company near by you could take motor to to have it checked?

Oonrahnjay · November 08, 2018, 06:30:17 AM

Quote from: chessie4905 on November 08, 2018, 05:18:56 AM... Do you have an electric motor repair company near by you could take motor to to have it checked?

Yeah, if there's an underlying problem with the (not-so-new) motor, it would be better to fix that before it shows up in other issues besides just with the ATS.

(PS - If the motor is OK, "Sure Start" and "Micro-Air" both recommend their soft-start kits for large-start-current motors like compressors. If the motor is working correctly and needs the help with an ATS, a kit might also be of benefit when of shore power, too; you never know when you're going to get a worn or tricky breaker on a shore power panel.)

Jim Blackwood · November 08, 2018, 08:30:08 AM

Let's make this simple. If it starts OK under 50psi then inertia isn't a problem but high pressure is. Sounds like you do have a functioning unloader. So what you need is more volume between your head and check valve. Possibly an accumulator tank of some sort. Your unloader reduces the pressure in that tank to ambient so that on startup there is no pressure resistance. You need to size your accumulator so that it stays under 50psi until after the compressor has reached full speed. There will be a larger and longer "hiss" when it stops but that will do the job for you.

Jim

dtcerrato · November 23, 2018, 05:11:17 PM

Well I finally ordered a transfer switch that should make wifey (& me) happy with no hhhuuuummmmmmm. Same manufacturer - ESCO because its in the identical enclosure so will make changeout easier. The shore power relay is NC (not activated) and the coils are DC & the drop out voltage is 90 compared to 107 on the current AC contactors. We'll see how it works - if it doesn't it's going back. We will also be looking into the items that were mentioned of the electric air compressor. Thanks for the input.

dtcerrato · December 03, 2018, 06:53:12 PM

Got the new transfer switch installed today. Works great, no hum, actually no nothing. The DC coil contactors are normally closed on the shore power side so the unit is dead silent. Wished I knew then what I know now about auto transfer switches when I purchased the 1st unit. Same company just designed differently. Thanks for all the input. Sometimes we learn the hard drive way...

Oonrahnjay · December 03, 2018, 07:40:11 PM

Quote from: dtcerrato on December 03, 2018, 06:53:12 PMGot the new transfer switch installed today. Works great, no hum, ...

Great, Dan, glad it worked out for you. Do you have a manufacturer and part number - sounds like an ATS I need. Thanks, BH

dtcerrato · December 04, 2018, 06:23:54 PM

Bill the unit we bought was the Esco LPT50BRD Lyght. It was the most expensive of the three units ($165.39 from RVUpgrades.) that satisfied our needs. I stayed with the same manufacturer for a simpler reinstall because the enclosure was exactly the same as the one it was replacing. The following units were also compatible in every aspect we were looking for: Power Max PMTS-50 (Burnstine's Distributors @ $155) and the WFCO T-57 50 amp ($143.29 from RVUpgrades.com). All three of these units mentioned are quiet instead of the annoying hum from AC contactors. The Esco is the only one I can vouch for - installation complete & very happy with it.

Oonrahnjay · December 05, 2018, 04:29:03 PM

Quote from: dtcerrato on December 04, 2018, 06:23:54 PMBill the unit we bought was the Esco LPT50BRD Lyght. ... I can vouch for - installation complete & very happy with it.

Thanks - nothing like personal experience! Appreciate the effort. BH

dtcerrato · December 05, 2018, 07:32:36 PM

Didn't mean to call you Bill - Bruce, good luck.

Oonrahnjay · December 06, 2018, 07:30:35 AM

Quote from: dtcerrato on December 05, 2018, 07:32:36 PMDidn't mean to call you Bill - Bruce, good luck.

Not a bit of upset from me, Dan. I just appreciate that you took the time to answer my question in the most helpful way. Y'all have a good day now!