Chuggs
RVF VIP
- Joined
- Nov 3, 2019
- Messages
- 328
- RV Year
- 2016
- RV Make
- Newmar
- RV Model
- Ventana 4037
- RV Length
- 40’
- TOW/TOAD
- Jeep JKU
This may never come up...but I recently troubleshot an issue I was having...so, I share this just in case.
My coach started tripping the generator breaker if I started it while on shore power. Normally, the transfer switch makes a smooth transition. That quit happening back in Oct or Nov... It’s not something I do normally, so it may have gone undetected for a while. My coach is a 2016...and this didn’t start until 2020.
I knew this had to be a transfer switch problem...so I ordered a new one from Amazon...installed it...and bingo. Good to go. I can start and stop the generator and power is again transferred back and forth smoothly. No breaker trips. To me...this is important because we rely on AGS in the event of shore power failure to keep our pet comfortable in the hot weather. In the unlikely event shore power was momentarily restored, during an AGS start...it could have tripped the Generator breaker and left the system dead in the water. My dog can’t reset the generator breaker. At least that I know of.
I decided to take a look and figure out how these things work. There are two contactors...and four relay positions on each. Three of the relay positions are to carry Line 1 (50A), Nuetral (70A, and Line 2 (50A)...then there is a fourth position which is a 6A rated Normally Closed relay, which they utilize for switching. The contactor on the right is for Shore power, the one on the left is for the generator. The generator contactor gets energized by a small circuitboard which looks for stable electrical service and then closes the generator contactor. The shore power relay closes automatically, anytime it has been energized, except for the fact it’s coil signal passes thru the NC relay on the generator contactor. So, it’s an either or, with generator priority. So, why was I getting breaker trips???
Somehow, both of my relays had the opportunity to connect for a split second at the same time, paralleling the shore to the generator. This is not supposed to happen. They place a mechanical interlock device, which is sandwiched between the two contactors with a pin that rides in a grove of the armature...one in each contactor. The day mine was assembled...they didn’t get the base of the interlock slide into the retaining groves of one of the contactors. This shoud have been apparent to them when they went to secure it to the cabinet. The contactors are held in by a pair of molded plastic retainers. There is an “A” side, and a ”B” side. Normally, the top of the contactors are held with the retainer oriented with the “A“ side out...it is a little wider than the “B” side...and it can only fit one way. Then the bottom retainer is supposed to be oriented with the “B” side facing out. This should have been their clue something wasn’t right. Nope, they flipped it over to the “A” side which has more allowance and screwed it down. This results in having space for the contactors to separate slightly, bypassing the mechanical interlock. And bingo...they make a connection at the same time and trip your generator breaker at the very least...and sometimes the shore power breaker as well.
So, this isn’t something they cover in the troubleshooting guide. But if you start having this exact issue...you might look for poor fitment of the mechanical interlock that is sandwiched between the two contactors. I checked mine out...found a bad NC relay on the shore power contactor, which isn’t used anyway...reassembled the parts correctly, and have a spare ATS for when a real issue arises with the second one I just installed.
I’m betting this is a very rare occurrence...but just in case —- Now you know.
Edit:
I am coming to the conclusion this started in July. We stayed at Crooked River S.P. and were having electrical issues. The line voltage was way low on one leg...but not the other. I went top to bottom, and while I was at it, took out the torque wrench to check terminals. While checking the torque in the contactors...since the wrong base retainer was installed, and the mechanical interlock NOT in their grooves...I’ll bet the contactor shifted just enough to let the interlock pin slip by. After all...I never noticed a problem before. It wasn’t until our Asheville trip in October that I noticed a trip. I’ve basically avoided starting the generator while connected to shore power most of the time after that. While changing my coolant in the generator, I was cycling the generator to flush...and had a trip again. So, I disconnected shore power, and finished the coolant exchange. I remembered this had happened a time or two before, so I ordered and installed the new switch. See...you do something you think will prevent issues...by torquing the connections...and wind up making more Work for yourself.
My coach started tripping the generator breaker if I started it while on shore power. Normally, the transfer switch makes a smooth transition. That quit happening back in Oct or Nov... It’s not something I do normally, so it may have gone undetected for a while. My coach is a 2016...and this didn’t start until 2020.
I knew this had to be a transfer switch problem...so I ordered a new one from Amazon...installed it...and bingo. Good to go. I can start and stop the generator and power is again transferred back and forth smoothly. No breaker trips. To me...this is important because we rely on AGS in the event of shore power failure to keep our pet comfortable in the hot weather. In the unlikely event shore power was momentarily restored, during an AGS start...it could have tripped the Generator breaker and left the system dead in the water. My dog can’t reset the generator breaker. At least that I know of.
I decided to take a look and figure out how these things work. There are two contactors...and four relay positions on each. Three of the relay positions are to carry Line 1 (50A), Nuetral (70A, and Line 2 (50A)...then there is a fourth position which is a 6A rated Normally Closed relay, which they utilize for switching. The contactor on the right is for Shore power, the one on the left is for the generator. The generator contactor gets energized by a small circuitboard which looks for stable electrical service and then closes the generator contactor. The shore power relay closes automatically, anytime it has been energized, except for the fact it’s coil signal passes thru the NC relay on the generator contactor. So, it’s an either or, with generator priority. So, why was I getting breaker trips???
Somehow, both of my relays had the opportunity to connect for a split second at the same time, paralleling the shore to the generator. This is not supposed to happen. They place a mechanical interlock device, which is sandwiched between the two contactors with a pin that rides in a grove of the armature...one in each contactor. The day mine was assembled...they didn’t get the base of the interlock slide into the retaining groves of one of the contactors. This shoud have been apparent to them when they went to secure it to the cabinet. The contactors are held in by a pair of molded plastic retainers. There is an “A” side, and a ”B” side. Normally, the top of the contactors are held with the retainer oriented with the “A“ side out...it is a little wider than the “B” side...and it can only fit one way. Then the bottom retainer is supposed to be oriented with the “B” side facing out. This should have been their clue something wasn’t right. Nope, they flipped it over to the “A” side which has more allowance and screwed it down. This results in having space for the contactors to separate slightly, bypassing the mechanical interlock. And bingo...they make a connection at the same time and trip your generator breaker at the very least...and sometimes the shore power breaker as well.
So, this isn’t something they cover in the troubleshooting guide. But if you start having this exact issue...you might look for poor fitment of the mechanical interlock that is sandwiched between the two contactors. I checked mine out...found a bad NC relay on the shore power contactor, which isn’t used anyway...reassembled the parts correctly, and have a spare ATS for when a real issue arises with the second one I just installed.
I’m betting this is a very rare occurrence...but just in case —- Now you know.
Edit:
I am coming to the conclusion this started in July. We stayed at Crooked River S.P. and were having electrical issues. The line voltage was way low on one leg...but not the other. I went top to bottom, and while I was at it, took out the torque wrench to check terminals. While checking the torque in the contactors...since the wrong base retainer was installed, and the mechanical interlock NOT in their grooves...I’ll bet the contactor shifted just enough to let the interlock pin slip by. After all...I never noticed a problem before. It wasn’t until our Asheville trip in October that I noticed a trip. I’ve basically avoided starting the generator while connected to shore power most of the time after that. While changing my coolant in the generator, I was cycling the generator to flush...and had a trip again. So, I disconnected shore power, and finished the coolant exchange. I remembered this had happened a time or two before, so I ordered and installed the new switch. See...you do something you think will prevent issues...by torquing the connections...and wind up making more Work for yourself.
Last edited:
