danemayer
Well-known member
Thanks Ted. The new switch is on a UPS truck somewhere nearby and should arrive this afternoon.
Transfer Switch Failure
- Thread starter danemayer
- Start date
danemayer
Well-known member
Installed the new switch this morning and all is back to normal. I was getting tired of choosing whether to use the extension cord for coffee or a heater.
I'm attaching pictures of the failed unit. There was obviously tremendous heat buildup because the insulation has melted off the wires and some of the wires are quite damaged. There's also a lot of soot.
My guess is that the contacts built up significant resistance over time causing the heat buildup and subsequent damage. I'll try to get a hold of Progressive's technical support tomorrow and will post if they have any other ideas.
I'm attaching pictures of the failed unit. There was obviously tremendous heat buildup because the insulation has melted off the wires and some of the wires are quite damaged. There's also a lot of soot.
My guess is that the contacts built up significant resistance over time causing the heat buildup and subsequent damage. I'll try to get a hold of Progressive's technical support tomorrow and will post if they have any other ideas.
Attachments
wdk450
Well-known member
Was your old transfer switch a Progressive? I have heard that they have a lifetime warranty.
danemayer
Well-known member
Yes, Progressive Dynamics - I'll ask them tomorrow. They told me today that the new one has a one year warranty.
HornedToad
Well-known member
danemayer, Glad all is well, thanks for sharing the photos.
Bill, I'm sold on your concept, kinda like cleaning your battery terminals, but from the photos I'm not sure where I need to be filing. Do you need to take something apart or would you use a very thin file between the silver set screw where the wire comes in and what looks a copper connecter on top?
Is the life of a transfer switch the hours under load or the cycles between shore power & generator?
Bill, I'm sold on your concept, kinda like cleaning your battery terminals, but from the photos I'm not sure where I need to be filing. Do you need to take something apart or would you use a very thin file between the silver set screw where the wire comes in and what looks a copper connecter on top?
Is the life of a transfer switch the hours under load or the cycles between shore power & generator?
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wdk450
Well-known member
Dan:
After looking closely at your photos, I am wondering if the wire connector screws on the relays were tight? Did you try them to see? Maybe we should focus more on this than contact pitting. I know it is a good idea to check the tightness of all of your circuit breaker connection screws yearly; maybe we should be doing this with the transfer relay, too.
On another note, there have been various suppliers of transfer relays, using various forms of relays. Some have the contacts exposed for filing and spraying, but the newer ones may not.
After looking closely at your photos, I am wondering if the wire connector screws on the relays were tight? Did you try them to see? Maybe we should focus more on this than contact pitting. I know it is a good idea to check the tightness of all of your circuit breaker connection screws yearly; maybe we should be doing this with the transfer relay, too.
On another note, there have been various suppliers of transfer relays, using various forms of relays. Some have the contacts exposed for filing and spraying, but the newer ones may not.
brianharrison
Well-known member
THanks for sharing the pics - Dan where is your EMS? load side or shore power? Pics are not a good way to troubleshoot but it appears the most damage is on the neutral connections, possibly where the lower cross over wires are connected. Is there a possibiity your generator neutral (at the generator) is loose? or ground wire loose?
Just a thought.
Brian
Just a thought.
Brian
wdk450
Well-known member
I did some more research on the stranded wiring and poor connections, and came up with a white paper on the Weidumier connectors website about adding gas tight ferrules onto stranded wire ends. The paper says that this is required by code in Europe. Correct size male spade connectors crimped, soldered and covered with gas tight (silicone-filled) shrink tubing would probably work well, too. There has to be some explanation for these failures, and the failures on new equipment makes me think wiring connection deficiencies rather than component (relay) failures are the root problem.
danemayer
Well-known member
I spoke at some length with Dave Watson at Progressive Dynamic Service. He was a bit surprised when he saw the photos. Said he doesn't usually see damage like that on both sides of the switch. The typical damage is on one side. His thought was it was probably due to a slightly loose/damaged wire at installation and that it degraded over time until there was so much damage that the relay would no longer operate. He said it could also have been started by contact pitting/damage (but I think he thought that was much lower probability). He also agreed that whether a loose/damaged wire or pitted contacts, the result was higher resistance driving higher amperage and high heat, damaging the wires and switch mechanisms, in turn worsening the situation until there was a failure of the relay to hold contact in either direction (shore or generator).
After this call, my guess, based on fairly symmetrical damage, is that it was not a loose wire, but rather was a contact problem. If it were a loose wire, based on Dave's comments, I think the damage would have been more severe on the side with the loose wire.
I asked him about the recommendation on this forum to turn off the main breakers inside so there's no load on the switch when applying power (shore or generator). He agreed that there's potential for arcing if the switch is powered when there's a load on the system and said turning the breakers off sounded like a good practice. But I don't think he would have gone so far as to say you have to do so to protect the switch.
He mostly sees defective units that are under warranty, so I suspect that may bias his experience toward installation issues rather than longer term wear and tear.
I did learn that the relay at rest doesn't pass power. It's energized for shore or generator and is held in the appropriate energized position the entire time power is applied from either source.
Brian, my EMS is on the shore power side.
After this call, my guess, based on fairly symmetrical damage, is that it was not a loose wire, but rather was a contact problem. If it were a loose wire, based on Dave's comments, I think the damage would have been more severe on the side with the loose wire.
I asked him about the recommendation on this forum to turn off the main breakers inside so there's no load on the switch when applying power (shore or generator). He agreed that there's potential for arcing if the switch is powered when there's a load on the system and said turning the breakers off sounded like a good practice. But I don't think he would have gone so far as to say you have to do so to protect the switch.
He mostly sees defective units that are under warranty, so I suspect that may bias his experience toward installation issues rather than longer term wear and tear.
I did learn that the relay at rest doesn't pass power. It's energized for shore or generator and is held in the appropriate energized position the entire time power is applied from either source.
Brian, my EMS is on the shore power side.
priorguy
Well-known member
I concur. Many buildings now do annual tighten and torque inspections on all electrical connections in disconnects, panels, switch gear etc. Preliminary exams are often done with infrared cameras to asses the "hot spots" (literally). Weak components and loose connections can be found before they fail. Also, Canadian electrical code requires all stranded connections be bunch tinned (soldered) or crimped. I'm sure American electrical codes are similar.
I'm sure all the bouncing an RV can do during travel could loosen connections over time. Even more so then a stationary building.
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wdk450
Well-known member
From my experience, I would strongly recommend AGAINST putting a stranded, tinned wire/cable into a screw-tightened pressure connection. Solder tinning wires in AC plug connections WAS common practice before I started in the Hospital Medical Electronics field in the 1980's, but most ALL of these connections were found to have loose screws within a year or two. All plug-in devices in a hospital were measured with an electrical safety tester then, yearly. I don't know the science behind it, but stranded tinned wires seem to compress some more over time in the screw connection. We were primarily concerned with good grounding to provide patient electrical safety, and the safety testers only measured this (and not how well the power screws were connected), but we often would find arcing and charring on the power connector screws while repairing the bad ground screw connections. You can imagine how this flaky supply power affected digital logic/microprocessor-based medical devices. The modern power cords for hospital devices are pre-made with soldered connections, and the clear plug body injection molded over these connections. I have yet to see one of these fail (other than the nurse pulling it out of the outlet by the cord!)
BTW, hospital plugs and outlets (green dot) consist of a special, heavier grade, components. The insertion and removal force is much higher than standard plugs/outlets to ensure good connections. Some computer power accessory companies use these components also, for their higher reliability.
And just a note to anyone thinking about doing infrared temperature testing of AC connections: The heating indication of poor connections is produced by a current flow, so you need to have the circuit involved heavily loaded for a short while (15 minutes) before checking for connection heating.
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danemayer
Well-known member
Duane, I didn't even bring it up. This thing is so damaged I think the only salvageable part would be the case and the ground buss. The electronics board might still be working, but even if it was, I wouldn't trust it.
HornedToad
Well-known member
I followed this thread, and the Bad Transfer Switch thread, with great interest. Seeing as one of my earliest post on the forum was... What is an ATS?, What does it look like?, Where is it at? and most of the time I use my (CLUNK) generator. I was able to take away a lot of good information, and that's what the forum really is all about, Thanks!!!
It is also good to know that if my ATS ever goes out...
I'll still have hot coffee, I never gave up my porcelain coffee pot and Maxwell filter packs from the old tent camping days.
It is also good to know that if my ATS ever goes out...
I'll still have hot coffee, I never gave up my porcelain coffee pot and Maxwell filter packs from the old tent camping days.
scottyb
Well-known member
I think there is a lot to be said for wiggling the stranded wire connections, then tightening them again. I suspect loose connections is what fried my 1st transfer switch at 2 days old. I know that when I have wired a new panel, it seems like I can always get another 1/2 turn on the lug after wiggling the wire.
