After four years in FIRST, I still have no idea what a fan is officially classified as. While I must admit I merely scanned the manual every year, this year, as a team leader, I took it upon myself to search out the answer to this question- to no avail (I actually read the manual-!!). Every year we get fans in the KOP, yet only this year have we considered actually using them. SO my questions here are severalfold:
What is a fan classified as- “motor” or electronic circuit?
What interface is required for a fan? If fans be “motors”, then a speed controller is necessary. If not, then I inquire as to what is exactly meant by the power distribution diagram when it has a blank box with terminals marked “fans”- does this warrant me to put in, say, an old breaker-board specifically for fans.
Following upon #2, what breaker should be used? The majority of fans in this world only use maybe an amp or two. Somehow, a 20A breaker seams to defeat the purpose of having a breaker.
If fans be not a “motor” does that allow the use of non-KOP fans- that is, simply a CPU cooling fan, since it is the ideal size for cooling medium items.
If a fan be not a motor, what size wiring should be used to connect to the interface.
I know these questions are a bit extensive, but as far as I can tell, the manual doesn’t have a sections devoted to these little creatures OR even the slightest mention (except for the Victor’s fans) of them.
A fan is a set of blades that, when turned, move air. To turn the blades, it has to be connected to a motor. That motor must be one of the kit of parts motors.
Edit: Sorry, I didn’t realize you were talking about the KoP fans; you said that in the opening paragraph but later you were talking about non-KoP fans as well. I thought you meant a device that you were going to use for maybe moving a ball around. If you were going to take apart a window fan and use that, my previous comments apply. Replies below are much more informative on KoP fans than I could be.
Okay fan=motor. Got it. But as a programmer at heart, I have to keep on asking questions (sorry!).
What breaker should be used for a fan? As far as I can tell, only the breakers in the KOP can be used, and the specs for a fan are far below the lowest amperage breaker.
Spikes are the only type of motor controller possible for a fan, correct? Fans utilize a DC brushless motor, and they use “sensitive” electronic parts inside, or so I thought. I could be way off…
What does the wiring diagram mean when they use that ambiguous fan “box” connected directed to the power supply board?
Sorry again… Thanks for all your help- I’m still a rookie at heart
The diagram is suggesting that fans may be connected directly to the PDB and this has been allowed in past years. The problem is that this is not really addressed in the rules and the Power Distribution Diagram is not part of the rules unless it is a Victor fan.
If you are looking at using the KOP fans on your robot I would ask the Q&A to verify they may be powered straight from the Power Distribution Board.
The breaker you should use is related to the wire size you use, and is detailed in the FRC game manual.
The purpose of a circuit breaker is to protect the wiring. It is intended to keep the wiring from overheating (and perhaps burning) in case of a short circuit. Its rating is not necessarily related to the normal current draw of the device being powered.
Ed,
I will get the message out on this issue. Previous years, the fans were at least called out in the wire size and breaker section of the manual. Fans have been viewed during inspections as COTS parts used in their original configuration (unmodified) and used for only for their intended purpose of cooling. Since the electrical rules specify 20 amp breakers as being the smallest allowed, a muffin fan still needed to be powered through this device. Electrical rules in the past of course had allowed all fans to be wired in parallel and fed from one breaker. The majority of easily obtained fans these days in the 12 volt DC flavor, are brushless types. This means that the motor controller is internal and needs no external motor controller. Some teams have used Spikes to turn fans on and off as they saw fit which also was allowed under the rules. Fans used for other purposes, i.e. ball control, need to be powered by KOP motors under all applicable rules.
Al, is there a rule i’m missing somewhere that prevents me from hooking up a KoP muffin fan to either a Victor/Jaguar or Spike to control it, and using it to drive some MECHANISM? I’m not really thinking for this game specifically, but for instance, last year, to perhaps drive some sort of ball agitator.
PS: yes I know, rules don’t apply cross-years, but the motor usage rules have been the same for as long as i can remember.
Hooking a muffin fan (or other brushless DC cooling fan) to Victor or Jaguar would likely kill it. Spikes, because they are simply relays, should produce no ill effects. There is no rules this year that relate to fans at all. Teams that wish to use fan/blower mechanisms for playing the game or other robot function (not simply cooling electronics) I believe come under the motor usage rules and as such are required to use KOP motors, not the motors that come with the assembly. I have had a few inquiries about using COTS blowers and fans and my response referred teams to the motor usage rules. I am not speaking for the GDC here but I am rendering an opinion on the way fans have been utilized in past years. When in doubt, ask the Q&A.
In addition, the rules imply that the fans supplied with the Victors should be attached. The manufacturer, IFI, requires them to be in place. If you use Victors, mount the fans and power them. The rules do allow that Victor fans be wired in parallel with the input power terminals at the Victor as recommended by IFI.
I can see your side but the rule that I point to…
<R52> Motors specifically permitted on 2010 FRC ROBOTS include:
A. All motors, actuators, and servos listed in the 2010 KOP,
This does not list fans. A word search of motor in the KOP checklist does not return any fans. Historically, fans have been considered something other than motors. The power available from a fan is tiny and often the rotor is an integral part of the fan assembly and not capable of being separated.
This rule does not specifically state that the motors in the KOP checklist must be labeled as motors in the KOP checklist, just that they must be on the list.
The Fans are in the KOP checklist (Blue tote, page 9 and page 10) labeled as Fans (compact Fan (large), Compact fan (Mini)). Therefore, they should be legal to use as motors.
Personally, I’d Q&A it, if I were wanting to use them for anything other than as a cooling fan
Yeah, as I said, its a sort of a loophole thats been there for years. Its not REALLY all that useful, as theres not really enough power/torque to be had there for something useful.
Just thought of it when reading this thread and couldn’t think of a reason it would be disallowed by any of the current rules.
Just to verify, this does not mean, however, that I can use a non-KOP fan, correct? I mean, I have a bunch of CPU cooling fans that are physically attached to heatsinks, and I would like to use the heatsink and fan together. If a fan is a motor, then this is disallowed, but if a fan is simply a COTS item, I am significantly less limited. Hiding a Muffin fan is a bit like hiding a six foot tall easter egg on Easter morning- it simply cannot be done without every little kid in a 500 mile radius sticking their fingers in!
Ed,
As there is no rule that currently prevents cooling fans from being used as cooling fans, I would consider them to come under the COTS definitions and therefore be allowed. Many teams have used fans and heatsinks in the past to cool motors and have always passed inspection. Lacking anything to the contrary from the GDC, I would also use that test in inspections this year.
However, the rules also lack any electrical rules governing the wiring of electrical fans used for cooling except those used on the Victors. I would expect that to be changed (watch all team updates) to all #24 AWG and a 20 amp breaker to feed all cooling/muffin fans provided <R45> is not violated…
E. Only one wire shall be connected to each WAGO connector on the Power Distribution Board. If multi-point distribution of circuit power is required (e.g. to provide power to the three KOP breakout boards via one 20-amp circuit), then all incoming wires must be appropriately spliced into the main lead, and only one lead inserted into the WAGO connector to connect the circuit.
