Sensor Rack Loose Lugs

[Colin]

Cleaning our 2001 vintage Sensor racks today and when pulling one module out, one of its load lugs came out with it. Cleared out some more space and found that a bunch of load lugs are zip tied in place. I'd never looked closely at how these are attached, but I see there's a wee little plastic bit that should snap into the square hole in the lug to capture it when it slides into its slot, and not surprisingly several were broken off and replaced with zip ties. Seems like poor design and another reason to power down your racks before pulling even one module, lest you have a lug come out too or probably worse go bouncing around inside the rack.

So my questions are:

When did this happen - at installation or at some later date? I've been with this facility for most of the life of these racks but was gone for a few years in the middle so can't say for sure. I've never had a lug pull out before when pulling a module. If this happened at installation, is the zip tie solution a legit one that an ETC installer would employ rather than replacing the broken part? Has ETC done anything more secure in later iterations of their racks? Anyone else encounter this?

 

[MNicolai]

Sounds like a great question for ETC.

cc/ @starksk @STEVETERRY

 

[Mac Hosehead]

Interesting picture. The broken locking tabs were most likely done by the installing electrical contractor. The shown fix is not approved by ETC which says the plastic carrier needs to be replaced. As far as I know, this is still the current design in Sensor racks. I would not say it is a poor design because I have only seen the tabs break with abuse and not module removal.

Just looking at the picture, I see moisture corrosion as well as the broken tabs. I think it is time to get a technician out to deal with the issues.

 

[STEVETERRY]

Cleaning our 2001 vintage Sensor racks today and when pulling one module out, one of its load lugs came out with it. Cleared out some more space and found that a bunch of load lugs are zip tied in place. I'd never looked closely at how these are attached, but I see there's a wee little plastic bit that should snap into the square hole in the lug to capture it when it slides into its slot, and not surprisingly several were broken off and replaced with zip ties. Seems like poor design and another reason to power down your racks before pulling even one module, lest you have a lug come out too or probably worse go bouncing around inside the rack.

So my questions are:

When did this happen - at installation or at some later date? I've been with this facility for most of the life of these racks but was gone for a few years in the middle so can't say for sure. I've never had a lug pull out before when pulling a module. If this happened at installation, is the zip tie solution a legit one that an ETC installer would employ rather than replacing the broken part? Has ETC done anything more secure in later iterations of their racks? Anyone else encounter this?


View attachment 16648

This rack should definitely be examined and repaired by an authorized ETC service technician. I suggest calling ETC Technical Services to arrange this. Since there is a potential safety hazard indicated by the green copper oxide on conductors, this should be done as soon as possible.

ST

 

[Colin]

Interesting picture. The broken locking tabs were most likely done by the installing electrical contractor. The shown fix is not approved by ETC which says the plastic carrier needs to be replaced. As far as I know, this is still the current design in Sensor racks. I would not say it is a poor design because I have only seen the tabs break with abuse and not module removal.

Just looking at the picture, I see moisture corrosion as well as the broken tabs. I think it is time to get a technician out to deal with the issues.

The update is after going through two SR48s and a 24 we had an additional two broken tabs (not previously zip tied). Like you say, it is possible these too could have been damaged at installation. The tabs are pretty thin where they flex, so although I have no experience with SR installation they seem awfully delicate to me and that surprises me in what's otherwise a pretty rock solid thing. All the lugs have some wiggle in them just from the tab having a little wedge shape rather than filling the hole in the lug completely, so that seems like it could help weaken the plastic over repeated pulls and pushes. But still, I've pulled a lot of thousands of modules in my life and this is the first day I've had this complaint.

I was a little surprised at the oxidation on maybe 8-10 lugs but we did have a humid couple of weeks over the summer 2-3 years ago when the AC in the room failed completely, and right now one of two wall mount ACs that cool the room is down. I'm going to measure humidity in there tomorrow. Weather's muggy here right now. We're presently working on funding for the CEM upgrade and rack re-warranty project so hopefully some service is coming soon.

 

[JD]

Used to see those copper-salts (green) on equipment after a summer in Wildwood (NJ.) The danger is that they can actually grow to the point where you have a path over the insulator and can flash. Once that happens, the carbonized plastic will serve as a conductor between the channels and it becomes a fire hazard. Cleaning them was easy enough on the portable equipment I was dealing with but in this case I think replacement is the only option. Plastic tends to get brittle over time and pressing the tab to release the contact would probably cause it to crack off.
Now, in this case, each module operates on it's own phase, and the distance between different module contacts is much greater than that of the contacts on the same module. Basically, the only time there is potential is when one channel is full on and the other is off, and would be limited to 120 volts. (Here in the US) Still, a sizzler is a sizzler irrelevant of the voltage.