I would like to consider using the panel mount version of the 120A breaker.
The data sheet shows that it has identical specifications, but it would allow for simple mounting in a plastic enclosure completely covering the electrical connections.
The battery connector could also be mounted inside the same box. It would be safer and more professional.
Rule #41: . . .“the one (1) main 120-amp (120A) circuit breaker (Cooper Bussman P/N: CB185-120),” . . .
The CB185F-120 is the standard version, while the CN185P-120 is the panel mount. Rule #41 does not specify the letter code.
Does anyone (Al?) know if the panel mount “P” version would be allowed?
LOL… Personally I’d like to use the CB285 because they have yellow indicators so I can tell students “push in on the yellow thing” rather than “flip the switch” and watching them fumble and mash the red button trying to hopelessly turn on the robot.
This is yet another antiquated rule that won’t be changed until people start complaining loudly.
But to answer your question… I suspect you’ll be told to look up the definition of the word “no” in the dictionary by Q&A if you ask to use this. They seem to frown upon substitutions for this part.
The short answer, no. The slightly longer answer, no the inspectors really want to see ALL of your wiring connections without waiting for you to open a box.
When asked in previous years Q&A wanted the exact part # cooperbussman breaker. They tend to be picky about these things. Not holding much hope for anything other than a snarky comment. :]
If your plastic enclosure requires opening a door or something to access the button, this would violate R47 even if the part is OK.
If you’re only talking about it covering the electrical connections but leaving the button and lever accessible, that much would be OK. Having to open a door to inspect is usually not an issue, but the main breaker and vent plug must be directly accessible.
Yes, the red button and reset lever would easily accessible (like any typical panel mount switch - since the panel mount surface would be flush & exposed). The electrical connections would be covered behind a clear plastic cover for inspection.
Or they’ll give you the 100% good and non ambiguous response of:
We cannot rule absolutely on hypothetical ROBOT designs, and the final decision as to legality of a particular ROBOT lies with the Lead ROBOT Inspector (LRI) at each event. If you have a question about a specific rule, please rephrase and resubmit.
[because it would kill them to say that all gearboxes are legal](We cannot rule absolutely on hypothetical ROBOT designs, and the final decision as to legality of a particular ROBOT lies with the Lead ROBOT Inspector (LRI) at each event. If you have a question about a specific rule, please rephrase and resubmit.) or that your robot can be whatever color it wants
This is an interesting one. I went to the website recommended in the KoP Checklist for this part, www.eaton.com/bussmannseries and searched for the part number provided.
That took me to a page for “High Amp Circuit Breakers”, which clearly list CB185-120 and CB185P-120 in separate tables. Yet the datasheet shows the numbering format the OP indicated.
It’s interesting to note that searching for “CB185-120” on Digikey returns only the panel mount version. Searching the same on Mouser returns only the flush mount version. In both cases, the “P” and “F” are not included in the part number.
In asking the Q&A, make sure you reference the datasheet and the ambiguity between the listed part numbering system and the part number listed in the rules. Something like:
“R44 lists P/N CB185-120 for the main breaker, but the datasheet for the breaker specifies a different part numbering system, requiring either Panel mount or Flush mount to be specified. Can either CB185P-120 or CB185F-120 be used?”
Technically speaking, if the rules specify CB185-120, and the actual model number for the KoP Breakers is CB185F-120, then in reality no one is using the correct breaker as the rules are currently written. :rolleyes:
@Jon Stratis: Thanks for the suggestion - I’ll get very specific in the Q&A. In fact I asked our student (who submits questions for the team) to use your exact question as stated.
IMHO, if the back side of the panel mount has its own plastic cover, that works for me. Electrical connections covered by electrical tape also works for me.
What doesn’t work for me is: The team claiming the plastic cover that the breaker is mounted to, adequately isolates the connections on the back. The cover keeps someone from touching the connections and getting a shock.
The problem I see is: If something comes loose inside the robot, behind the panel cover, then that loose piece could touch the exposed connection and create a spark. Or, worse yet, fry the device it is connected to, and cause a fire.
If FIRST engineering were to allow an alternative breaker, I expect they would want evidence that the alternative would perform all of its safety-critical functions in the same way as the one already allowed. Most businesses that make or sell products with safety-critical functions require such evidence when a part change is being considered.
If I were asked to determine whether an alternative breaker will perform safety-critical functions in the same way as the present breaker, one piece of evidence that I would want would be a detailed comparison of the internal construction features of both breakers.*
Does anyone out there have pictures showing such a comparison?
Also, as pointed out above:
And a tool dropped or mishandled while working on the robot could short-circuit the rear mounted terminals of the -P version MUCH more easily than those of the -F version. This would make consequences of violating the rule (R42 this year) requiring complete insulation of exposed terminals MUCH more severe.
*I would also want data from several kinds of testing, performed on the basis of relevant standards and using repeatable, reproducible methods.
I think the point is that the rules don’t specify the breaker that comes in the KOP, you could also use the flush mount version, as it carries the same part number.
The danger from uncovered battery wiring is not shocks, it’s heat from being shorted…
Agreed - as is current standard practice the electrical contacts would be protected from inadvertent contact, either by electrical tape or inside a complete enclosure.