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Secondary transfer switch 2001 u320

Our secondary transfer switch has failed. This is a Parallax/Magnetek ATS100. This is discontinued. The replacement is said to be the ATS501, but this is 11 3/4" deep, won't fit the space under the bed. I previously replaced the primary transfer switch, a Lyght lpt ca, with a Lyght lpt50 brd.

The Lyght lpt50 brd looks like it will fit the space but the connectors are all on the same side. This adds a wiring issue as the ats100 has the input on one side, the outputs on the other. Has anyone found a good replacement for the ats100 with the same wiring configuration and the same size? It's really tight working in that space, hate to add complications.
Mike & Molly Patronick
2001 U320 40'
2011 Forester

Re: Secondary transfer switch 2001 u320

Reply #1 –
ATS100 contactor contacts (50-amp points) are available to replace pitted points. We just changed all 6 points, so our transfer switch is as good as new again.

What is wrong with your 2nd ATS100 (inverter vs shore/generator)? How do you know it is broken?

If you saved your first failed transfer switch you could change it points and probably make work again.

Some think that the ATS100 has advantages over newer transfer switches.

Re: Secondary transfer switch 2001 u320

Reply #2 –
Barry
Where did you get the new points? part numbers?

On two occasions, while on shore power, the coach switched to inverter. On both occasions breaker 8 (marked charger) on the main panel was tripped. Talked to tech at Magnum (we have a Magnum inverter), but no help. Talked to James Triana at FOT. He opined the transfer switch had failed and that all power in the inverter subpanel was coming through the 20 amp circuit breaker #8. When we tried to use more than 20 amps in the subpanel, #8 would trip and the inverter would then take over. Keith Risch at MOT did check the transfer switch and verified it is not switching.

I changed out the primary transfer switch because it was humming, driving me nuts trying to sleep. The new transfer switch uses DC contactors which supposedly will not hum. So far, all is quiet. Kept the old switch as emergency spare. Would like to repair the old switch if I could find contactors.

Is it likely the failure I describe in the secondary transfer switch would be fixed with new contactors? Does the ATS 100 use AC or DC contactors? Humming an issue?

Thanks much.

Thanks
Mike & Molly Patronick
2001 U320 40'
2011 Forester

Re: Secondary transfer switch 2001 u320

Reply #3 –
We replaced our ATS under the bed about a year ago.  Kept tripping.  It still would trip on occasion when we exceeded 20 amps an that #8 breaker.  We replaced our inverter/converter with a Magnum MS 2812.  I talked to the Tech at Magnum re: the ATS tripping and he said that there are 2 ways to eliminate this.  1.  Replace the #8 breaker with a 30 amp and the feed wire.  or 2.  Remove that ATS and wire directly through the 2812.  He advised that there is a transfer switch built into the inverter.

What follows is an email thread between me and their Tech Rep Darren Massey.

Me:
"We some times have our Charger Breaker trip.  Based on the attachments of the coach wiring diagram and the Electrical Panel Breaker IDs, am I correct to assume that the 20 Amp Charger Breaker, that lives in Circuit Breaker Box #2 is powered by the 20 Amp breaker- #8 -  from the Main Circuit Breaker Box?  Why would the Charger Breaker trip?  Would appreciate your input."

Darren:
"I would recommend using a 30 amp breaker. Our inverter/charger will use 18 amps and full charge rate which will only leave 2 amps for pass through I see you have a bypass transfer switch on the output but not sure which position is priority."

Me:
"Can I run the 6/2G power line directly to the inverter converter and then run the inverter/converter output directly to  Circuit Breaker  # 2 and bypass Switching Relay #2?"

Darren:
"You could do that but you will need to move the 6/2G wire from the main buss in the main panel to thirty amp breaker or wire the inverter for single in single out 60 amp and change the wire on the output of the inverter to 6/2G also. This is because the 6/2G there now is protected by a 50 amp breaker and all wire must be sized for that size overcurrent protection. FYI I would probably do this if it was my installation, one less failure point."

I have not done anything yet as the breaker is not tripping often these days.

Hope this helps.  ;D
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Secondary transfer switch 2001 u320

Reply #4 –
Scott and Carol
Appears we have the same problem. On our coach the main power panel, the inverter subpanel and the secondary transfer switch all live under the bed. The inverter is mounted on the wall of the first curbside storage bay. Pulling that heavy wire from the engine bay to the inverter and back looks like a major deal. MOT agreed so we decided to just replace the transfer switch. If we can repair it, that would be even nicer.
Mike & Molly Patronick
2001 U320 40'
2011 Forester

Re: Secondary transfer switch 2001 u320

Reply #5 –
As referenced above, you can probably replace the points.  We just replaced the ATS.
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Secondary transfer switch 2001 u320

Reply #6 –
ATS-100 use two Furnas contactors. Replacement points are called "contactor kits" and are packaged for one pole, so the two contactors use 6 packages. ATS-100 contactor kits are part # 75BE42. Google it and find several hits at different prices.
http://www.electricalcontactkits.com/contact_kits.asp?Eck=FN75BE42&Ref=furnas

There is a rectifier mounted on the inside wall of the ATS-100, and the shore power contactor coil uses the rectifier to power it with 120-volt DC. The generator contactor coil uses 120-volt AC.

The shore power contactor also has one coil to pull in and another coil to hold the contactor closed.

I am not sure why your Magnum is tripping breaker on main panel. Check Romex wire size to see if it is larger than #12 (20 max) to see if you can easily change breaker to larger amps. That breaker only powers Magnum's battery charger. When breaker trips, the battery charger must be drawing more than 20 amps, which is a lot of 12-volt amps.

When tripped it thinks Magnum lost shore power as start inverting, which is normal and probably not a transfer switch fault.

We only have one transfer switch. I am not sure how the 2nd transfer switch is wired. I assume it feeds the inverter sub panel from the 2nd transfer switch output, with inverter feeding one contactor and main panel feeding other contactor.

I will say that any contactor that transfers with a live high amp load, like microwave, roof air, space heater or other heating element, will cause pitted points.

Not sure if pitted points will cause a hum, probably not as hums usually come from contactor AC coil.

Re: Secondary transfer switch 2001 u320

Reply #7 –
Barry
On our coach the secondary transfer switch inputs are a 50 amp line from the main panel and a 30 amp line from the inverter. The main panel also supplies a 20 amp line (circuit 8) to the inverter/charger. If the secondary transfer switch fails in such a way that it can't pass power directly from the main panel, but can still pass power from the inverter, then the inverter pass through will still pass the 20 amps from circuit 8 through to the inverter subpanel.

When you add up the loads from the battery charger, a microwave, and a toaster oven, that 20 amp breaker on circuit 8 in the main panel gives up. Then the inverter can no longer see shore power or gen power on circuit 8, so it starts inverting. The change  can be so fast we don't notice until the inverters low battery cutout shuts down the inverter subpanel.

Your description of how a transfer switch works makes me think that one or both shore power coils in the transfer switch has failed. I suppose it's also possible there was arcing that welded contactors closed. If it's the contactors, $100 for 6 new contactor kits would be a bargain.

Unfortunately, I know very little about electrical controls. Fortunately, a friend is visiting next week and happens to be an electrical engineer with a lot of practical skills. Is there a site with a parts list for the ATS 100? I went to the Parallax site and they have the manual but  I couldn't find a parts list that would identify the coils.

Thanks

Mike & Molly Patronick
2001 U320 40'
2011 Forester
 

Re: Secondary transfer switch 2001 u320

Reply #8 –
Mike, I have been thinking about your 2nd transfer switch and you just answered my questions.

Looking inside the 2nd transfer switch would give you some info. The ATS-100 gives priority to the Shore Power contactor, the one with the pull-in & hold coil, and the one with the output wires connected.

Since the 50-amp is hot with shore power, and the Magnum bypass internal relay will flow your 20-amps to the other contactor, both contactors are powered and if the priority wiring is backward Isolator panel would be powered from 20 amp breaker, or inverter.

It seems that the 50-amp should flow to shore power contactor, and the inverter to generator contactor.

And if a contactor does not transfer, it could also set up the wrong current flow.

ATS-100 has several interlocks to prevent both contactors from closing when both are energized. And a problematic interlock could also cause the problem.

Problem is probably in the 2nd transfer switch and not the Magnum.