putting auto-reset breakers on spikes in 2012
 

I'm re-posting http://www.chiefdelphi.com/forums/sh...ad.php?t=18817

Does anybody know if it is legal to put auto-resetting breakers in the fuse sockets on the spikes?

Concluding to R58.E it only mentions "The fuse on a relay feeding the compressor may be replaced with a 20 Amp Snap-Action circuit breaker (recommended)." but it doesn't forbid it on other uses? :confused:

Re: putting auto-reset breakers on spikes in 2012
 

You can use the auto-reseting ones on the spike for a compressor, and it's recommended, but the other ones don't need it. (if you're out of the little yellow non-resettable ones though you MAY use the black reseting ones)

Hope that helps.

Re: putting auto-reset breakers on spikes in 2012
 

Here is the entire rule that includes the compressor Spike allowance:
(emphasis mine)

By replacing the fuse in a Spike with a breaker, you are modifying the performance (it will continue to function after an overcurrent event, which it probably would not with a fuse). While this probably won't harm the Spike, and the Spike is already supposed to be protected by a 20A breaker on the PDB, it is nonetheless a modification. The reason that it's allowed for the compressor is that the compressor draws a large startup current, which tends to blow the Spike fuses; having the breaker allows the compressor to keep running.

Short version, I'd call it illegal except on the compressor Spike; this is the safe call. (You could make the argument that it's legal on every Spike, but you'd probably be pressed to hold that position.)

Re: putting auto-reset breakers on spikes in 2012
 

I don't even think this one is worth arguing (this year); it's pretty clear that replacing the fuse is explicitly a modification (this year).

I doubt that adding a 20 A or smaller Snap Action VB3 breaker would cause any ill effects in an FRC application, so this is definitely something that we should have FIRST address for next year. I think I'll run this by IFI, though, to see if they actually care. If it's fine by them, maybe FIRST will relent.

Re: putting auto-reset breakers on spikes in 2012
 

Concluding to http://www.vexrobotics.com/products/.../217-0220.html
" Ideal for 2 independent solenoids, light, pumps.
Design will accept auto-resetting circuit breaker.
Compact design.
"
It should work if I replace the 20amp with a 20amp auto-resetting circuit breaker

Just wanted to know if there is any first rules about this or any feed back from other teams is appreciated :)

Re: putting auto-reset breakers on spikes in 2012
 

And, as I said, there is a rule. No modification, except on the compressor Spike.

Re: putting auto-reset breakers on spikes in 2012
 

I'm a little bit confused. Is replacing a fuse with a auto reset fuse considered a "modification"? We are not taking the spike apart? For example replacing a fan on the victor with another fan is not "modifying" the performance of the victor.

So replacing the 20 amp fuse with a 20 amp auto reset fuse isn't changing the performance of the spike correct? :confused:

Re: putting auto-reset breakers on spikes in 2012
 

Darkorbit,
As said before, you can only replace the fuse on the spike connected to the compressor. Replacing any other is illegal and you cannot do it! You may replace blown fuses another fuse of the same value. Also I think you mean "according to" not "concluding to", or "my conclusion from the information presented in "

You will see no practical performance gains from doing this modification anyway. The compressor sometimes needs it because of the very large starting loads. Your auto reset breaker will likely trip before the fuse blows.

Re: putting auto-reset breakers on spikes in 2012
 

The fan is not a modification in that it is functionally identical. If you were to place a fan on a victor that is higher flow, or lower current or something that would be a modification. An auto reset breaker is not functionally the same as a fuse, in that it will reset itself, the fuse will not.

You cannot do it, it is illegal, we will find it, you will have to change it back.

Re: putting auto-reset breakers on spikes in 2012
 

The prohibition in [R58] is against "tamper[ing] with, modif[ying], or adjust[ing] in any way". Therefore, you must ask whether replacing the Spike fuse or the Victor fan constitutes any of those things. If that was the extent of the rule, you'd have an open question for the Q&A.

But this year, the rule specifically describes several exceptions—i.e. permitted forms of "tamper[ing] with, modif[ying], or adjust[ing] in any way". One exception says: "The fuse on a relay feeding the compressor may be replaced with a 20 Amp Snap-Action circuit breaker (recommended)." Therefore, replacing a fuse with a breaker is a form of "tamper[ing] with, modif[ying], or adjust[ing] in any way".¹

As for the Victor, that's a bad example, because it could change the performance, and it would also invoke the motor rule, [R48].

¹ Unless you want to argue it's only tampering/modification/adjustment when you're doing it to a Spike attached to a compressor—but I don't think the inspectors will go for that.

Re: putting auto-reset breakers on spikes in 2012
 

The Vex web site says the spike is designed to use the self resetting breaker which you can buy on the same page. You are certainly not modifying the Spike by using one. It is not specifically disallowed in the rules. There is a good argument that it is by implication. Ultimately it will the officials at the tournament will make their interpretation the one you will have to live with.

Re: putting auto-reset breakers on spikes in 2012
 

The bolded part is why we're saying it is a modification.

What is in there stock from the manufacturer is a fuse. Fuses, as you know, are "one and done"--if they take an overcurrent, they are no longer functional and the device that uses them is no longer operational until the fuse is replaced, which takes until after the end of a match. This is the COTS configuration of a Spike.

When you replace the fuse with a self-resetting breaker, the breaker will reset after an overcurrent breaks the circuit. This is NOT the same function, as the breaker does not need to replaced after every time it takes an overcurrent. The device is operational as soon as the breaker resets, which takes a matter of seconds or less. This is not the COTS configuration of a Spike.

Because the performance has been altered, the Spike has been modified from COTS. The rules disallow any modification of control components from COTS unless the modification is specifically allowed. The replacing of a fuse with a breaker is only specifically allowed on one Spike, and that is the one for the compressor.

Therefore:
1) You are modifying the performance of a Spike by using a breaker instead of a fuse.
2) Modifying the performance of any control system component by any means other than an exception is specifically declared to be illegal.
3) Therefore, replacing the fuse with a breaker is illegal in the general case.
4) For the compressor Spike, the replacement of a fuse by a breaker is specifically declared to be both legal and recommended. Therefore, for that Spike only, it is legal.

You cannot make a good argument that because IFI says it's designed to accept the breaker, it is legal to use the breaker instead of the fuse provided. IFI has no control over FRC rules (AKA legality). That's like saying that because an RS775-18 is designed to handle 18V, an FRC robot can run a circuit on 18V. And the implication is, quite simply, no modification. That is what the rule says. That is how multiple veteran inspectors see it. And I'd give it a 90%+ chance that your events inspectors will see it the same way.

Re: putting auto-reset breakers on spikes in 2012
 

But again, to quote [R58]
If you look at item E, under the exceptions, you are allowed to swap out the fuse only on the compressor's spike. Since the language is specific enough to include changing a fuse for a breaker under the exceptions to the rule, it can be inferred that doing this to a non-compressor spike is in violation of this rule, regardless of IFI's recommendations.

If the GDC intended this to be legal, I feel that item E would read a little differently; specifically mentioning that the fuse could be changed on all spikes, not just the one controlling the compressor. But since it's not, I would say that changing the fuse on any other spike would be a modification, and therefore illegal - it would be acceptable only on the spike controlling the compressor.

To me, this is pretty clearly illegal with this year's rules, but there's probably a good case for changing it in the future. But for now, I think you're stuck with the fuses...

Re: putting auto-reset breakers on spikes in 2012
 

Guys,
IFI designed the Spike with a fuse to protect the relay contacts on the two relays that make up the working part of the Spike. When pneumatics were allowed to be used on the robot, users found that the compressor start current was slightly higher than 20 amps and this would result in an untimely demise of the fuse (during a match). IFI recommended that for the compressor only, the fuse be replaced with a 20 amp circuit breaker. FRC accepted that recommendation and made it part of the rules we see today. The Spike is not designed to control electrical loads greater than 20 amps. The robot rules continue to reflect that design requirement by not providing for teams to modify the Spike except when used with the compressor. If you are using the Spike to control a motor and the fuse is repeatedly opening, then you are drawing current in excess of that which will damage the Spike. Your only choice will be change the output coupling to lower the current or to replace the Spike with a speed controller.

Re: putting auto-reset breakers on spikes in 2012
 

IFI are the ones saying that the Spike is designed to accept the self resetting CB.

The old (2010) compressor draws a lot more than 20 amps on start up. It is just about unusable with a 20 amp fuse. If the concern is the CB does not protect the relay, you need a beefier relay, not an exception to the rules.

If your running load is close to twenty amps,then you need to use something besides the spike. Which is why the rules do not allow you to run CIMs & FP motors on a spike? If you have something with a high inertia load (slow start, more time in the high current area or something subject to occasional short stalls, the CB would be a good solution using the same logic that makes it acceptable for the compressor.

I have been lazy. I have been meaning to ask the GDC for clarification. Several of inspectors have commented that they think it is against the rules. So I expect that will be the general consensus of the people that matter. (The game officials.)

BTW Replacing the spike with a JAG on a 40 amp breaker is not a good way to protect your motor. You still need to make an educated judgement on why you were blowing the fuse & what should be done about it. Not that anybody was suggesting that this would be a good idea.

Re: putting auto-reset breakers on spikes in 2012
 

FrankJ--

The compressor is a special case, compared to something like a window motor. The compressor has high start current, but it is not really possible in an FRC robot to stall the compressor motor. It is easy to build a mechanism that can stall a window motor.

Re: putting auto-reset breakers on spikes in 2012
 

Frank,
We are saying that it is illegal under the current rules. This is not an opinion.

The Thomas compressor lists 25 amps as the max start current with 10.5 amps run current. The Viair compressor is listed at max current of 10 amps but I suspect start is much higher.

Re: putting auto-reset breakers on spikes in 2012
 

At Kettering we had auto-resets in our motor spikes before inspection, and it was questioned. I said that it was not clear in the rules, and the inspector said he would review with the head inspector and get back with me. I said I had the fuses, and we can replace, but I would like to know if it is legal, as we blow the fuses, when we jam a ball. I never had a response from the head inspector, or the original inspector. We blue all of our spare fuses and and a few from donated ones from teams after 3 matches. I put the auto resets back in to complete. I did make an effort to find an inspector, and check at the "service desk" in the pits, who could not locate one to verify, before I replaced them. The service desk did have the printed rule book, and I read the rules again, and did not where it was disallowed. I too agree that replacing the fuse with a breaker is not modifying, the manufacturer allows it, the rules recommend it for the compressor, and the one of the rules read an approved current limiting device, which the breaker is... although I could not find an approved list, it comes in the kit of parts.

I also had 3 new jags and 3 old victors on hand. I lent 2 of the jags out to other teams, 1 came back missing the magic smoke, and one never returned.... (so much for GP I guess)

I will have victors on the bot for the next competition.
Ball jammed in your conveyors with banebots motors, and drivers that jam you hair whipper motors under bridges, will eat your fuses....

I was searching here to see if there was a discussion, and there was. :)

Re: putting auto-reset breakers on spikes in 2012
 

At SD one of the inspectors told us that we should switch to the autoreset breakers for our motor spikes. I was confused when he told us this because I was fairly certain it was not allowed (I told my team to be ready to swap them out again), but I went ahead and did it.

Re: putting auto-reset breakers on spikes in 2012
 

The rules explicitly state:
Replacing the fuse with a resetting breaker is permitted only for the compressor - otherwise, you are changing the factory conditions of the fuse and altering its performance. If you put the breaker in, you'll be able to run the fuse longer at higher voltages before that breaker trips, AND you'll be able to run it again on the field after it trips. In both cases, the performance is not identical to what it was before the change.


I can understand your frustration in blowing fuses with your motors, but take this as a learning opportunity for your team. If you look at the specs for the motors in the KoP this year (available here, the link can be found on the KoP website), you can see which motors (most of them) will draw more than 20A at stall - the stall current is listed clearly. Based on that, you can make a decision on what to use. If your motor is operating in a way that it will never stall and never pull more than 20A, go ahead and use a spike. If it could stall (like your ball collector), then avoid using a spike unless its one of the motors that doesn't draw more than 20A at stall (like the right Window motor).

Re: putting auto-reset breakers on spikes in 2012
 

As a general protection scheme, most motors will blow the their fuses at stall. If not their fuses then some other over current device first. For a device designed not to stall this is a good thing. The problem comes when you have a device that will stall occasionally as part of its function. The First scheme it to run it with current protection that is too high to provide it with any protection.

An exception is something like a window motor that is designed to run stalled for short period of time & they generally have some kind of thermal switch.

I do not buy the replacing the fuse with a self resetting breaker is a modification, but if you read the robot inspection sheet, it pretty well implies it is against the rules which in the end is the only thing that matters. Especially since the rules allows you to use a victor on a 40 amp breaker and completely smoke your motor. :(

Hopefully the rules committee will review this for next year & either allow a beefier relay or a self resetting breaker on the spike.

Re: putting auto-reset breakers on spikes in 2012
 

Everyone,
The fuse on the Spikes may be changed to a breaker for the one and only Spike that controls a compressor. No other fuses may be exchanged for breakers. The condition exists that most motors in the KOP this year are capable of much higher currents than the Spike is designed for, exclusive of stall. By changing the fuse, you violate the manufacturers specification on this part and it is possible that you would violate the warranty on the Spike. Your choice is to modify your design so that run current on the motor of your choice is less than 20 amps or change your Spike to a speed controller.
I am sorry that the LRI did not get back to you. He may have tried to get in touch with me but didn't have my phone number or asked me after the fact. In any case, your fuses musst be replaced for your next competition.
Al

Re: putting auto-reset breakers on spikes in 2012
 

Not so sure on that, as the manufacture states here http://www.vexrobotics.com/217-0220.html

"Spike is a 20 Amp, H-Bridge Relay Module that is small enough to be remotely mounted almost anywhere on your robot. Spike is designed for driving small motors in forward, reverse, or stop (brake). Spike is opto-isolated at the signal input to protect the Robot Controller against motor noise and return currents. Requires a 3-wire cable for connection to the Robot Controller.

Ideal for 2 independent solenoids, light, pumps.
Design will accept auto-resetting circuit breaker.
Compact design"

Bold for emphasis by me.

So I would contend that using the breaker is not against the manufactures specifications. Also on that page, they sell the auto reset breakers.

We now have victors, and are very happy with the performance.

Re: putting auto-reset breakers on spikes in 2012
 

Scott,
The breaker reference is for the compressor only and that recommendation came from IFI years ago.

Re: putting auto-reset breakers on spikes in 2012
 

The short of it is that you can ask the GDC for clarification, but until then the ultimate interpretation of these rules rests with the Chief Robot Inspector. He has made his interpretation very clear in this thread and at LRI training. It is a very consistent message. FRC does not allow the use of a circuit breaker in a spike that controls a motor. If you'd like to see that changed, ask the GDC.

I know it is frustrating, but this is one of the areas that we have to be painfully conservative.

Re: putting auto-reset breakers on spikes in 2012
 

Incidentally, I e-mailed IFI technical support to ask if this was an acceptable configuration (in their mind). They declined to express an opinion directly, noting that since the breaker was not manufactured by them, its suitability was "out of our scope".