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Transfer switch issues (ATS 501 by Parallax Power Supply)

I have ongoing issues with ATS 501 by Parallax Power Supply on my '96 270.

It was installed on 11/15/2012 so it is almost 4 years old.  PO warned me it takes time to have it switch from generator power to shore power.

When I use generator power, then it takes long time to transfer to shore power when I turn off generator.

Also my coach losing power time to time and when my coach lose power (115v) I feel the click (electro-magnet relays in the box)
when I run my front A/C so I turned off A/C and wait for couple of minutes then power came back.

So far ok, but it is very frustrating losing power time to time.  Shore power is fine.

No breakers are tripped at all in fuse box.  I think my ATS 501 unit is having problems....

Right now it is 110v.  I was wondering if ATS 501 would go off when it is under 110v?  Sometimes I feel like bypass that box and have shore power line connect directly to the line that goes to the fuse box.

Should I go buy another ATS 501 or what?  I see it cost $250 plus shipping at Amazon.
1996 U-270
Build # 4951
Cummins 8.3

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #1
Good thread here about ATS problems, removal hints, and one possible alternative:

Transfer switch questions

OR, if you decide to replace existing unit:

Parallax ATS503 50 Amp Transfer Switch
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #2
Jamie,

No, the transfer switch will not cut off because of voltage below 110 VAC.  Guess there is a voltage at which it would cut off, but WAY below where you would damage A/C's, etc.

Most ATS's have built in timers when switching power sources. Some are owner settable. Pull out the owners manual or get the manual on-line to find out if yours can be adjusted.

Another suggestion:  With shore power off, inverter off, generator off, remove the lid to the ATS.  Check that all connections are tight and not burned.  Carefully look at the points of the switches to make sure they are not burned.  As with any "switch", transferring under heavy load WILL arc and burn the points.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #3
That Blue Sea manual switch is NICE....  That will do. 

Hmm I see ATS 503 is newer unit, replaces 501...  Will stop by RV store nearby to see if they have them in stock.
1996 U-270
Build # 4951
Cummins 8.3

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #4
Not much to adjust the ATS 501.  Just a switch for timer disable switch and three jumper wires (for 35A aux capability).  Good point about tighten the clamping screws.  Removed the cover and did not see anything burned.
1996 U-270
Build # 4951
Cummins 8.3

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #5
Tighten wire clamping screws (two were bit loose and one of ground wire clamp is loose) and I even checked and tighten the 50 amp power cord ends (one I use to connect to my coach shore power interface).  Still have same issues of losing power and then come back in couple of minutes then again losing power and so on.

So I decide to run generator and it works fine, no power losses at all.

Right now I am working on directly connecting shore power to fuse box (running through surge and power monitoring box) bypassing that ATS box for now (using buss connectors).  I am thinking of buying manual switch and get rid of that ATS.

Since generator has to turn on or off manually so it is no point having ATS box so manual switch is far much better.

Interesting that the ATS box to surge/power monitoring box is 8 gauge wire, it should be 6 gauge since we are using 50 amp.
1996 U-270
Build # 4951
Cummins 8.3

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #6
After connecting the wires bypassing the ATS box, turned on shore power and it came on then went off.  Turns out that Progressive Ind EMS-HW 50C box is cutting off the power.  I have not looked at the error code, but it looks like the voltage is too low (EMS will cut power when voltage drops to 104v or below).  So I turned off the EMS box (there is remote switch) and then power came back on.

It is odd because I tested the RV park electrical connection with meter and it says 114 volts (on both 50 amp and 15 amp outlets).

I have voltage meter in my coach and it says 111 volts right now.

I guess ATS box is working fine (one thing bothers me is too long time to transfer between generator power and shore power).
1996 U-270
Build # 4951
Cummins 8.3

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #7
After connecting the wires bypassing the ATS box, turned on shore power and it came on then went off.  Turns out that Progressive Ind EMS-HW 50C box is cutting off the power.  I have not looked at the error code, but it looks like the voltage is too low (EMS will cut power when voltage drops to 104v or below).  So I turned off the EMS box (there is remote switch) and then power came back on.

It is odd because I tested the RV park electrical connection with meter and it says 114 volts (on both 50 amp and 15 amp outlets).

The power at the pole sounds like it's marginal.  Without a load you're reading 114 V, but once the coach is plugged in the load it presents pulls the power down.  I would not risk running an air conditioner if the EMS isn't allowing power to pass.


I have voltage meter in my coach and it says 111 volts right now.

Has it been verified against a known?  We found our power line monitor was off by a few volts compared to what our Fluke 87 read.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #8
Jamie,

Voltage may read fine when you check the CG pedestal, but the CRITICAL ISSUE is what is voltage when you turn on large loads.

If the power company is providing the CG with 120 VAC, but the CG wiring is inadequately sized, with no load you could read 120 VAC.  And with heavy load, could read 104 VAC.  Very often happens when everyone else is running heavy loads, stressing the CG wiring.

So, I strongly recommend one of the digital voltmeters that you can plug into any outlet in the coach to monitor voltage as you turn on heavy loads.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #9
Voltage may read fine when you check the CG pedestal, but the CRITICAL ISSUE is what is voltage when you turn on large loads. If the power company is providing the CG with 120 VAC, but the CG wiring is inadequately sized, with no load you could read 120 VAC.  And with heavy load, could read 104 VAC.  Very often happens when everyone else is running heavy loads, stressing the CG wiring.

Which has happened at a couple of Parks we've been at. At first, I thought it was a problem with one of my ACs. After a CB worth of damage after a surge, I bought a EMS, I rest much easier, now.  ^.^d
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #10
Checking with my digital voltmeters and it is showing 104 volts off from my coach outlet and showing 105 volts off from power on pole.  No wonder my EMS was cutting off the power.

It is really hot and humid and I have to run A/C, I guess I have to run off generator power bypassing shore power.  Not good considering I pay for a site. :(

Checked other power pole and it is showing 102 volts, oh man.  I guess it is entire park.  S&H Campground off from I-70 in Greenfield, IN (near Indy).

Right now I cannot run generator anyway until we put wires back into ATS box.
1996 U-270
Build # 4951
Cummins 8.3

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #11
There are Hughes(?)autoformers that will reduce everyone else's power on your circuit while building up yours.

At least that's how I understand they work...

Edit:  just purchased the 50 amp model for our coach
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #12
Other bad news my Montague Paratrooper folding mountain bike has been stolen :(. Lucky I still have RadRover electric bike, man I am going to lock this up!

Update: Found my bike by park office, probably a kid took my bike for joyride.
1996 U-270
Build # 4951
Cummins 8.3

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #13
There are Hughes(?)autoformers that will reduce everyone else's power on your circuit while building up yours. Edit:  just purchased the 50 amp model for our coach

Let us know (link?) how that works. I don't like a full-hook 50 amp park where I'm ALWAYS concerned about power drop & shut-down.  >:D
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #14
Other bad news my Montague Paratrooper folding mountain bike has been stolen :(. Lucky I still have RadRover electric bike, man I am going to lock this up!

Update: Found my bike by park office, probably a kid took my bike for joyride.

I looked at the info on your RadRover.  Seems like a real value/nice bike.

I had to mod our prodecos as the twist throttle was not easy to use as you could not use all your hand to hold on.

Went to a thumb throttle instead, 

Plus changed the grips, bars and riser to make it taller and the flat grips saved our palms from bruising

Added a cave creek seat post with rubber bumpers in it
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #15
Let us know (link?) how that works. I don't like a full-hook 50 amp park where I'm ALWAYS concerned about power drop & shut-down.  >:D

Amazon has the info and the unit.

Probably not the cheapest but convenient
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #16
There are Hughes(?)autoformers that will reduce everyone else's power on your circuit while building up yours.

At least that's how I understand they work...

Edit:  just purchased the 50 amp model for our coach
It only coverts by lowering the amps to boost the volts. The park power is not affected.
How Does it Work? | Hughes Autoformers
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #17
It only coverts by lowering the amps to boost the volts. The park power is not affected.
How Does it Work? | Hughes Autoformers

Thanks for the link.
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #18
Ditto ^.^d  I've not run mine down below 110, but I'd sure buy one should that start happening!
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #19
Bought Hughes Autoformers and they do work very well, boosting the voltage from like 108 to 118-120.  Very pleased with this purchase.

Bad news, my both bikes RADRover and Montague Paratrooper has been stolen when I parked my coach at Walmart overnight in Fairbault, MN :(. $2,500 worth of bikes bye bye....  Someone use bolt cutters to cut the security cable.  I should have used the chain, oh well....
1996 U-270
Build # 4951
Cummins 8.3

 

Re: Transfer switch issues (ATS 501 by Parallax Power Supply)

Reply #20
Bummer!!!

I love my RadRover!!!
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)