Posted by Eric Rasmussen.
Engineer from FIRST.
Posted on 8/1/2000 12:59 PM MST
Hi all.
I need to ask your opinion on the use of 20 versus 30 amp breakers for the motors. Tom Frank suggested to me that a 20 amp auto-resetting breaker does a good job of protecting the Fisher-Price motors from burning themselves up. Looking at the set of motors in the kit in 2000, it would therefore seem logical to replace all the breakers with 20 amp breakers, with the exception of continuing to use 30 amp breakers on the drill motors.
Naturally, this might lead to some teams experiencing additional breaker trips during matches, while hopefully extending the life of the motors. My question is whether or not teams, on the whole, would prefer this extra level of safety, or if it would be better to continue to allow teams to burn up motors while gaining some extra short-term performance.
What do you think? (We need to decide this quickly so that we can order the parts and get them in time to pack the kits.)
Thanks,
-Eric
Posted by Justin Stiltner.
Student on team #388, Epsilon, from Grundy High School and NASA, American Electric Power, Town of Grundy.
Posted on 8/1/2000 2:10 PM MST
In Reply to: Circuit breakers posted by Eric Rasmussen on 8/1/2000 12:59 PM MST:
Why not Put both in the kit and let the teams choose which one to use?
Justin Stiltner
Team #388
Epsilon
Grundy Va,
Posted by Andrew Rudolph.
Student on team NASA KSC/Michael Krop Senior High School from Michael Krop Senior High School sponsored by NASA Kennedy Space Centre.
Posted on 8/1/2000 5:49 PM MST
In Reply to: Re: Circuit breakers posted by Justin Stiltner on 8/1/2000 2:10 PM MST:
: Why not Put both in the kit and let the teams choose which one to use?
i totally agree with you more choices is what we are looking for
Andrew
team 212
Posted by Joe Johnson. [PICTURE: SAME | NEW | HELP]
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
Posted on 8/1/2000 7:50 PM MST
In Reply to: Re: Circuit breakers posted by Andrew Rudolph on 8/1/2000 5:49 PM MST:
I prefer to allow teams enough rope to hang themselves.
The motors are definitely the easiest to turn into toaster (and believe me we have smoked our share), but I feel that we have learned to live with them as they are.
We have learned how much load we can put on them and how much cooling we have to provide them and how hard we can push them.
The first year they were in the kit we never made it through a tournament without at least one fan melted off the armature. This year, with the exception of a motor burned up during program debug, we never lost a motor. So… I think that this is a case of letting us hang ourselves if we want to.
I vote against 20 Amp breakers as a mandate. I could go for an optional construction rule. But… I suppose that my preference would be for things to stay as they are.
Joe J.
Posted by Mike Gray.
Engineer on team HOT from Huron Valley Schools sponsored by GM Milford Proving Ground.
Posted on 8/2/2000 6:09 AM MST
In Reply to: I vote for smokin’ motors! posted by Joe Johnson on 8/1/2000 7:50 PM MST:
20A breakers prevent maximum use of the FP and van door motors, and they may not do anything for the motors protected with a positive tempco thermistor (window lift motors). The Globe motor should be protected by a fast-acting 20A breaker.
It’s good to have options for several design approaches. I would use a 20A breaker on the Globe motor
if there is potential for stalling. 30A breakers on every other motor.
If a team wants to cripple their machine with an undersized breaker on the FP motors, then they should have that option. At least the machine will continue to play.
I think that two 20A breakers should be provided in the kit. Most teams will use only one of them, some will want three. I see the decision-making as an excellent opportunity to lead students through an interesting, though potentialy frustrating exercise in ‘risk assessment’.
Posted by Ken Patton. [PICTURE: SAME | NEW | HELP]
Engineer on team #65, The Huskie Brigade, from Pontiac Northern High School and GM Powertrain.
Posted on 8/2/2000 4:39 PM MST
In Reply to: I vote for choice. posted by Mike Gray on 8/2/2000 6:09 AM MST:
I agree with more protection for the Globe motors, but not for any of the others.
Ken
Posted by Bill Beatty.
Other on team #71, Team Hammond, from Team Hammond.
Posted on 8/2/2000 8:45 AM MST
In Reply to: I vote for smokin’ motors! posted by Joe Johnson on 8/1/2000 7:50 PM MST:
Let folks choose. If they smoke out, so be it.
Bill B
Posted by Andy Grady. [PICTURE: SAME | NEW | HELP]
Other on team in limbo from in limbo sponsored by in limbo.
Posted on 8/3/2000 2:54 PM MST
In Reply to: I vote for smokin’ motors! posted by Joe Johnson on 8/1/2000 7:50 PM MST:
I personally would rather smoke the motors like Joe says. Those breakers if they trip in the middle of the match can cost a team dearly. This is a game of seconds, and everytime a breaker trips some of those seconds go down the hole. (Breakers may have litterally cost my team a championship in 96!) So i say, let em rip, or at least give us a choice.
Posted by Raul. [PICTURE: SAME | NEW | HELP]
Engineer on team #111, Wildstang, from Rolling Meadows & Wheeling HS and Motorola.
Posted on 8/3/2000 5:47 AM MST
In Reply to: Circuit breakers posted by Eric Rasmussen on 8/1/2000 12:59 PM MST:
Please do not limit us by making us use a 20A breaker on the FP motors. Include it in the kit if you can and let us decide if we want to use it or continue with the 30A one.
Raul