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pic: How we cool our compressor
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Re: pic: How we cool our compressor
This is not a joke this is really the configuration of our compressor.
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Re: pic: How we cool our compressor
Wow, that looks "cool" lol. quick question, today after my team was doing some neat re-wiring our compressor would not go on, after rigorous checking with the multimeter, the pwm cable leading to the compressor practacly exploaded, and the black cable was the only one that melted like crazy, do you think it happend because of how hot the compressor gets, or of some other reason.
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Re: pic: How we cool our compressor
Thanks for the cool comment, lol. The first thing i would say is that the compressor should be hooked up with at least 18 guage wire, i used 14 to wire our compressor. Also electricity is the flow of electrons, which are negatively charged. They flow from positive to negative, and since the black wire is the negative thats why it melts. Also if you wire your compressor and it doesn't turn on but just melts the wire then you probably have a bad compressor or something has jammed in the motor causing the charge to build up and melt the wire. If you have more questions im me at etakto738
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Re: pic: How we cool our compressor
cool, thanks everyone
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We were so glad that we had not fried the RC nor anything else for that matter. |
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Make sure all cables and power leads are hooked up correctly polarity wise, and when they are right, make sure they're tight! It'll save you alot of headaches later. |
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to be honest with you....that is really not necessary. The compresssor is built to perform.....so it is inevitably going to get hot...but it is supposed to do that. We run our test board with the compressor and we push that little thing pretty hard, it gets so hot you cant touch the top but its fine. And the match is very short, only a few minutes, so the compressor will only be on a max time of the match time, which is pretty brief, but still very demanding of the compressor. If weight is an issue for you guys, i would consider removing that.
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On a side note (in the past) COTS fans have been considered motors and are illegal. I looked around the Q&A and didn't find anything, so you might be okay, but don't be surprised if you fail inspection at your event(s) and have to remove it. If your compressor gets too hot to the point of where you need a heatsink after running it for 2 minutes (or less) then something is probably wrong with your compressor. Our pneumatics demonstration board has ran for several hours straight before when the programmers were working with it .. and the compressor got warm/semi hot to the touch, but nothing worth being concerned over, and nothing that could cause any burns or raise any safety concerns (although common sense is a different story) JMHO :) |
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if the compressor is running in reverse, it will still work but not as well and it will get very hot very quickly. you might want to check that it is running the right way.
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Since I didn't want to start a new thread, I thought I would go off of this one since it seems to be pretty relevant to my question.
Can a compressor burn out? I know that all of ours will get very hot with extended use. I want to know because we are rebuilding our T-Shirt Shooter robot. We are going to use 3 compressors to reduce the stress on the compressors and to speed up the fill time. Back to my original question though, can a compressor get so hot that it ruins the gaskets inside the compressor? Also as a side note for any other teams that look at this. I took apart the compressor yesterday just to check things out (this is our 2004 compressor and it is missing a bolt in the back and a bolt in the panel on the front. The front panel isn't air sealed at all, it's just a sound dampener. If you take the front panel off, you will see the piston and the motor output. Theoretically it shouldn't matter if you run the compressor in reverse, it should heat up in the same time. Also for the motor, there is no diode to control the flow of current. The "Thermal Protection" is just for the motor and not for the compressor itself. The "Thermal Protection" is a circuit breaker inside the compressor that trips if the current exceeds it's limit (I'm not sure what that limit is though) I have a way to attach a thermistor to the top of the compressor to detect the temperature, but it wouldn't be legal in competition because I took out one of the top screws on the compressor and torqued it back down, so it would be modifying. The thermistor seems to be fairly accurate and shuts the compressor down at the same temperature as it's programmed to do. The only reason I asked if it can burn out is because this adds a lot of complexity to the system with programming, visual alerts to the OI, and then the custom circuitry (the circuitry is the easiest part though :D). But please help me. |
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1) Electrons absolutely flow; but from negative to positive. Unfortunately the definition of "current" is the flow of positive charge (even though no positive charge carriers are flowing in these circuits, thank those dudes from the 1800's for defining current before they knew the existance of electrons), and thus we say current flows from positive to negative. This is a commonly misused/misunderstood concept. 2) The current in the black wire is no different than the current in the red wire and no different than the current in the motor windings inside the compressor. It is a series circuit (red wire --> Compressor --> black wire) and thus the current flow must be the same everywhere (conservation of charge). Perhaps the black wire melts first because it's insulation can't stand the heat and/or it is a higher AWG than the red wire resulting in more heating (I^2*R)? |
Re: pic: How we cool our compressor
Ryan,
If this compressor is used as intended the only death will occur with old age. As others have pointed out in this thread, the motor occassionally is wired incorrectly and it runs backwards. The compressor is not as efficient and so takes longer to come up to shut off pressure. The result is added heat from the motor and added heat from the compressor running a longer time between cycles. The thermal breaker inside the motor is to protect the motor from burning up due to a locked compressor or from trying to start with a high "head" pressure. Both of which would exceed the design current for the motor windings. The compressor start current can be about 25 amps and run current will be about 10-12 amps under normal conditions. Remember that compressing air causes a significant rise in temperature and in a compressor there is frictional heat added as well. Under normal use, these temperatures are accounted for in the design. This compressor is not intended for continual use however. A fan for cooling in this case would be acceptable under the rules for robot use. I would have to see your use of a thermistor to be able determine if it fits the robot rules. In any event the thermistor would have to be used as a sensor, insulated and returned to the RC or custom circuit as a sensor input. The Spike controlling the compressor can only be fed by the RC to be legal. Mounting the thermistor using one of the compressor head bolts might be an issue, but I can't think of anything off the top of my head that could consider that a modification of the compressor. If you drilled and tapped a hole, that is a modification. I could think of several ways to attach a thermistor that would not disturb any of the hardware and still work effectively. If you are adding three compressors in parallel, I would think a check valve at the output of each one would be appropriate. This would prevent problems when one of the compressors starts later than the other two. It would also prevent starting with a high system pressure. Just a thought. Doug, the black wire, I think, was referring to the PWM cable. This is a fairly common occurence when the PWM cable is connected inproperly or contacts the +12 volt line at the other end. Happens more often than I would like but is an effect of using RC components in this application. |
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We used our old T-Shirt shooter for football games and for robotic demonstrations. The new one will be much safer and more reliable than the old one. |
Re: pic: How we cool our compressor
Ryan,
I can bring that question up to other inspectors but I still do not feel that using an existing bolt qualifies as a modification. I would again have to see it for sure. Adam, Hole theory as you pointed, out is a method to help in understanding the physics of semiconductor operation. Electrons do exist and they are the reason electricity works. They flow from the negative terminal to the positive terminal or from an electron source to a more positive terminal. (Remember opposite charges attract.) Think of a vacuum tube, the electrons generated by the filament and cathode material (thermionic emission) are attracted to and flow to the positively charged plate. As Doug pointed out, early pioneers did not know the actual physics and assumed that current flowing in a wire produced a magnetic field that would affect a compass, naturally flowed in one direction from positive terminal to negative terminal. Since there are no positive charge carriers there is no way for current to flow out of the positive terminal. These early electricians then defined a current flow as something they could measure and that is the "conventional current" flow we use everyday. When using an ammeter in a DC circuit connected so that the positive terminal is connected to the more positive source, an up scale meter movement will result. Hence the confusion between electron and conventional current flow. |
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