putting auto-reset breakers on spikes in 2012

[darkorbit]

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?

[Steven Sigley]

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.

[EricH]

Here is the entire rule that includes the compressor Spike allowance:

[R58]
The control system is designed to allow wireless control of the Robots. The Driver Station software, FirstTouch I/O module, cRIO, speed controllers, relay modules, wireless bridge, and batteries shall not be tampered with, modified, or adjusted in any way (tampering includes drilling, cutting, machining, gluing, rewiring, disassembling, etc.), with the
following exceptions:
[...]
E. The fuse on a relay feeding the compressor may be replaced with a 20 Amp Snap-Action circuit breaker (recommended).
[...]
M. Devices may be repaired, provided the performance and specifications of the component after the repair are identical to those before the repair.

(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.)

[Tristan Lall]

Originally Posted by EricH

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.)

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.

[darkorbit]

Originally Posted by Tristan Lall

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.

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

[EricH]

Originally Posted by darkorbit

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

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

[darkorbit]

Originally Posted by EricH

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

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?

[Tristan Lall]

Originally Posted by darkorbit

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?

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.

[Justin Stiltner]

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.

[Justin Stiltner]

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.

[FrankJ]

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.

[EricH]

Originally Posted by FrankJ

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.

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.

[plnyyanks]

But again, to quote [R58]

The control system is designed to allow wireless control of the Robots. The Driver Station software, FirstTouch I/O module, cRIO, speed controllers, relay modules, wireless bridge, and batteries shall not be tampered with, modified, or adjusted in any way (tampering includes drilling, cutting, machining, gluing, rewiring, disassembling, etc.), with the
following exceptions:
[snip]
E. The fuse on a relay feeding the compressor may be replaced with a 20 Amp Snap-Action circuit breaker (recommended).

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...

[Al Skierkiewicz]

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.