Globe motor to spike controller

[stephenthe1]

Can the globe motors be hooked up to a spike speed controller? That's all, Thanks

[Biff]

Originally Posted by stephenthe1

Can the globe motors be hooked up to a spike speed controller? That's all, Thanks

Yes, the only motors not allowed on spikes are the Cim's both sizes and the Fisher Prices . The converse that If you want to run all your motors on Victors you are allowed to. The section of the manual that relates is the robot section.

[dez250]

While i can not find a rule currently saying you can't use the globe motors on a spike relay, i would not suggest it. FIRST recommends here that you use a victor for a globe, and i would suggest the use of a victor too. A spike relay gives you an on or off state while the victor motor controllers gives you a variable control of the motor and will also let you back up the motor with a 20 amp circuit breaker.

[BrianBSL]

Originally Posted by dez250

While i can not find a rule currently saying you can't use the globe motors on a spike relay, i would not suggest it. FIRST recommends here that you use a victor for a globe, and i would suggest the use of a victor too. A spike relay gives you an on or off state while the victor motor controllers gives you a variable control of the motor and will also let you back up the motor with a 30 amp circuit breaker.

Why?

If we look at the spec sheet - http://www2.usfirst.org/2005comp/Specs/Globe_Motor.pdf, it shows a stall current of only 22A. If you look at the snap action circuit breaker spec sheet, it shows it needs 10 full seconds at the circuit breaker rating to blow. Therefore, I see no problem with running the Globe on a 20A breaker, and using a spike, if you don't need speed control. This could save a team nearly $100, if they didn't have to buy another speed controller.

[Andrew Blair]

I agree. Especially if you replace the fuse in the SPIKE with an auto-reset, which is legal. You're probably not going to stall the motor for very long, and if you do, you'll burn it before you hurt the spike, I would think. The only thing your team needs to decide is if they need the variable control of a victor. If not, make it easy in yourselves, right?

[Tristan Lall]

Originally Posted by Andrew Blair

I agree. Especially if you replace the fuse in the SPIKE with an auto-reset, which is legal.

By <R61> this is specifically legal for the compressor; however, it is implicit that for any other device, this constitutes an illegal modification to the Spike (since it is specifically permitted as a modification, in one exceptional case only).

Also, if we interpret 5.3.9.1 in a consistent sense, to "protect" a circuit refers to the presence of an appropriate breaker in the panel, and not (necessarily) in the Spike itself, if present. (I say consistent, because the same phrasing is used to refer to Victors, which lack an integral fuse.)

So while that section may have been the source of the confusion, it appears that FIRST intends that the Spike fuses remain as installed, and an extra breaker be used to protect that circuit in a redundant fashion. From an electrical standpoint, I don't really see why this is necessary, or even desirable—why mandate the use of two devices of the same current rating to protect a circuit, when one circuit breaker would be simpler, or two circuit breakers would be more useful (albeit exceptionally redundant)? Even a manually-resettable circuit breaker ought to be allowed (but isn't) in place of the fuse. This rule seems to be one that keeps appearing in this form, and I'm not really sure why.

[BrianBSL]

Originally Posted by Andrew Blair

I agree. Especially if you replace the fuse in the SPIKE with an auto-reset, which is legal. You're probably not going to stall the motor for very long, and if you do, you'll burn it before you hurt the spike, I would think. The only thing your team needs to decide is if they need the variable control of a victor. If not, make it easy in yourselves, right?

I believe this is only legal on the spike running the compressor -

<R61> The control system is provided to allow wireless control of the robots. The Operator Interface, Robot
Controller, Speed Controllers, Relay Modules, Radio Modems, Batteries, Battery Charger, AC Adapter, and
9-pin cables may not be tampered with, modified, or adjusted in any way, (tampering includes drilling,
cutting, machining, gluing, rewiring, etc.) with the following exceptions:
• The dip switches on the Operator Interface may be set as appropriate.
• The user programmable code in the Robot Controller may be customized.
© FIRST 2006 FIRST Robotics Competition Manual, Section 5 – The Robot, Rev C Page 18 of 30
• The Speed Controllers may be calibrated as described in owner's manuals.
• The fuse on the Spike relay for the Air Compressor may be replaced with a 20 Amp Snap-Action circuit
breaker.

But if you have to worry about the globe blowing the fuse, then you have a mechanical design problem (stalling the motor).

[Andrew Blair]

Huh, I could've sworn that it was on any SPIKE. It doesn't make any sense to use one on the compressor. It wouldn't seem that the compressor would ever draw that much current.

[lukevanoort]

Originally Posted by Andrew Blair

Huh, I could've sworn that it was on any SPIKE. It doesn't make any sense to use one on the compressor. It wouldn't seem that the compressor would ever draw that much current.

Strange. I thought the same thing, but the 2006 AND 2005 rules clearly state this. Hmmm...

[KenWittlief]

In the past teams had problems with the 20A fuse in the spike for the compressor blowing. When the compressor kicks on with an almost full tank it is near stall current, and repeated long enough a fuse will eventually fatigue and blow.

Allowing breakers in the spike for the compressor is a compromise, to keep teams from going through matches with no air pressure. Other motors that you use, driven by the spikes, should never be near stall current.

[Al Skierkiewicz]

Guys,
You are missing the point on using circuit breakers on the robot electrical vs. the protection provided by a fuse in the Spike. The circuit breakers are chosen with minimum rating for protecting the wiring. (See R82, 83, 84) A 20 amp circuit breaker will keep a #18 from setting itself on fire in the event of a short. The 20 amp fuse in the Spike protects the contacts in the relay from destruction but does not protect the wiring since it is at the end of a wire run. Since the compressor draws more than 20 amps during start but has a run current much lower, IFI and First have determined that the fuse may be replaced by an auto reset circuit breaker for the compressor control only.
The globe motor can be used with a Spike with the understanding that you have no speed control. Only one motor per Spike, please.
All Chalupas (large and small) and all FP motors must be connected to Victors per R87.

[Tristan Lall]

Originally Posted by Al Skierkiewicz

Guys,
You are missing the point on using circuit breakers on the robot electrical vs. the protection provided by a fuse in the Spike. The circuit breakers are chosen with minimum rating for protecting the wiring. (See R82, 83, 84) A 20 amp circuit breaker will keep a #18 from setting itself on fire in the event of a short. The 20 amp fuse in the Spike protects the contacts in the relay from destruction but does not protect the wiring since it is at the end of a wire run.

Bearing in mind that this is (of course) totally illegal for FIRST purposes, what would be the effect of placing a jumper (or, alternatively a 100 A fuse) on the Spike, and a 20 A breaker in the panel, as usual? For a reasonable length of wire, wouldn't the 20 A also lend sufficient protection to the Spike, or is the Spike so sensitive to a current spike ( ) that it requires protection very close to the source of the fault? (If that fuse doesn't blow very quickly indeed, I don't see how that could be the case, though.)

[KenWittlief]

putting a 20A fuse in the fuse box would work the same as having it in the spike itself. If you wanted to do that I dont know why it would be against the rules

but why would you want to? When a fuse blows that circuit is dead for the rest of the match. Breakers are better: if something momentarilly stalls a motor, or even if something gets across the motor terminals both a fuse and a breaker will protect the components and wiring

but only a breaker will keep trying to reset (and restore power) during a match.

[Al Skierkiewicz]

You are correct that electrically it would perform the correct protection. But there are still two very good reasons to follow the electrical rules for the robot. The first is inspectors will be happier and secondly, IFI will be more likely to repair damaged units under warrantee when they know they have been used in accordance with the rule book. Remember that the fuse on the spike is nearest the motor and any fault there will not be isolated by several feet of wire (resistance) or the proximity to other bodies that may slow the reaction time of the fuse.
The electrical rules in particular have been well though out and cover as many bases as possible in an attempt to keep your robot running without settting the field on fire.

[Sachiel7]

We had used the globs on spikes in the past, and in my opinion they get better use off a spike than a victor. Most of the applications for globes only require directional movement, not variable speed.
We passed inspection with it at VCU in '04, but when we got to Nats we were told "we weren't allowed to run the globes off a spike". I couldn't believe it, so we ended up taking that mechanism off the robot (goal hook)
I concur, globes should be used for simple applications, thus not meeting the 22A stall, and should be perfectly fine for a spike.