Foretravel Owners' Forum

Hello all, it's been some time since I've posted here.  That's just generally because my rig has been running perfectly.  Who can complain right?

Well I started the generator to exercise it and I could hear the transfer switch under the bed thumping over and over again.  I'd see the voltage display by our inverter/charger panel briefly light and shut off each time and I'd hear the generator sag a bit each time this happened.  I didn't do much in the way of troubleshooting and left it.  A couple days later I started it again and it was working fine.  I walked away from the coach and I heard the a/c shut off and on again.  I shut power off at the breaker on the generator and turned it back on and all was well for hours.  But regardless I suspect the transfer switch.  We have an MTS 20k.

I read through this page and I noticed something.  It says the expected behavior is that if shore power is present it will be supplied and generator power will be on a 45 second delay.

I think ours is wired backwards.  When we plug into shore power there was always a long delay, like 45 seconds before you'd hear the box thump and we'd have power.  When we start the generator we have power instantly.  If you run the generator with shore power plugged in, the generator overrides.

Which brings me to the root thing I'd request comments on.  If my switch is wired backwards it means the CR2 over/under voltage relay would only be functioning when on generator power.  When this relay fails does it have a tendency to switch on and off every 1-1.5 seconds?  My suspicion is that is the root cause of my generator output rhythmically turning on and off.  I don't think I have the typical generator power cable issue at the junction box.  Everything in there is done very well to the point that if anything was going on, it'd be a dead short.

I also see evidence that the MTS 20K came out before.  Only one of the 3 screws holding the black board down is present.

Thanks in advance!

PS: It's very strange to see all these posts from "Mark Duckworth" in the forum and think "hey I didn't write that!" ;)  I guess the Mark Duckworth's are taking over Foreforums.

Mark,

Realizing I am viewing this long distance, I think you have assessed the problem correctly.  Your diagnostics certainly seem to match the symptoms.  My ATS's work as the book describes: Instant transfer for shore power, a 1.5 minute delay for the generator and the shore power has preference over the generator when both are present. 

Are the wire leads under the foot of the bed of sufficient length to switch the shore lead and generator lead between the ATS boxes?  Does it appear that they may have been moved in the past?  Our coaches are of sufficient age that stranger things may have ben done in the past 18 years. 

Good luck with this one. 

Richard

It's best practice to never run the generator while plugged in to shore power.

Ran our generator today while solving a generator problem. Generator took preference over shore power. (Gen took over the supply).  My 94 Bluebird was the same way.

On the Bluebird:
Generator has priority 1
Shore priority 2
Inverter priority 3.

Our 2003 U320 appears to operate the same.

IIRC there were some built with shore-preference, maybe 2002, early 2003.  The schematics for a coach will show you how that one is wired.  Look for "Primary Power Source" in to "Switching Relay #1" (aka main transfer switch).  (yes, 6106 is wired generator as primary power source  ;D  )