Fire at Michigan State Champs

[Mark Holschuh]

Does anyone know what was the specific heat source that started the fire, and what the combustible material was that sustained the fire?

[Drivencrazy]

Originally Posted by Mark Holschuh

Does anyone know what was the specific heat source that started the fire, and what the combustible material was that sustained the fire?

/u/sourec commented on the reddit post detailing the fire and showing some more pictures.

An expensive, unfortunate incident.

[Matt C]

We had a similar incident at the Long Island regional in 2009 with Team 263. That was the result of the catastrophic failure of a Victor speed controller, sustained by bumper material. The facility manager wouldn't let the robot back into the building unless they determined it was fixed and wouldn't happen again.

[Jaci]

I hate to be 'that person', but it has to be said.

Why did it take so long to grab a fire extinguisher that should have been ready at the field?
Why is there a group of volunteers all standing around a robot with a roaring fire and a live battery inside it?
Why are there volunteers sticking their hands inside and/or near the robot, let alone fanning the fire?

It seems to me like this reflects a lack of training for what to do in this situation. I would expect volunteers to be properly inducted about what to do in the event of an emergency such as this one. We've got 6 highly dangerous machines on the field and dozens more behind the curtain, all with massive batteries and electrical currents running through them, but it seems that no one knows what to do in the (quite likely) event that something goes wrong.

We're always saying that "Safety comes first", but it's events like this that make me question "are we really living up to that?"

[orangemoore]

Originally Posted by Jaci

I hate to be 'that person', but it has to be said.

Why did it take so long to grab a fire extinguisher that should have been ready at the field?
Why is there a group of volunteers all standing around a robot with a roaring fire and a live battery inside it?
Why are there volunteers sticking their hands inside and/or near the robot, let alone fanning the fire?

It seems to me like this reflects a lack of training for what to do in this situation. I would expect volunteers to be properly inducted about what to do in the event of an emergency such as this one. We've got 6 highly dangerous machines on the field and dozens more behind the curtain, all with massive batteries and electrical currents running through them, but it seems that no one knows what to do in the (quite likely) event that something goes wrong.

We're always saying that "Safety comes first", but it's events like this that make me question "are we really living up to that?"

Training for an emergency and being in one feel completely different.

I don't believe you can fault volunteers who aren't exactly sure what to do when they go to maybe 3-4 events a year. If they were trained for an emergency like this the chances of this happening has to be close to 1 in 100 events. So it isn't like this is something that happens so often that they would know how to react if it did.

I do agree there should be a fire estinguisher at the field to be easily found. And that perhaps maybe they shouldn't have been standing so close to a fire.

What are your concerns with a battery and fire?

[Jaci]

Originally Posted by orangemoore

What are your concerns with a battery and fire?

It's moreso that a battery rupture could cause massive damage to the internals of the robot and any close components assuming the bellypan of the robot isn't fully enclosed.

It was stated that the fire was caused by a battery short with a live chassis. If a robot is on fire, 9 times out of 10 it will be because of a battery short or electrical fault. When a high amperage electrical circuit shorts, touching the metal chassis of the robot is a good way to become less alive.

[Kevin Sevcik]

Originally Posted by Jaci

When a high amperage electrical circuit shorts, touching the metal chassis of the robot is a good way to become less alive.

You might be badly burned if the frame is hot, but Ohm's law plus physiology says you're extremely unlikely to suffer any injury from the electricity itself. Wikipedia says the resistance of wet skin is about 1 kOhms. So a 12V battery can push, say, 12 mA through you. The chart on that page notes that 12 mA of AC would be noticeable after a few seconds, but not deadly. It's important to note that DC is much less dangerous in this regard than AC. Unless you have wires connected directly to your heart[1], it takes a lot more DC to kill you than AC. If anyone is doubtful, I can hold a demonstration at Champs where I will bravely grab both terminals of a robot battery with either hand an suffer no ill effects.

Mind you there's plenty of other dangers from the battery, but they're all the fire, explosion, direct-short causing a welding arc sort.

TL;DR: The robot battery (and your car battery[2]) aren't going to electrocute you unless you stab a positive and negative wire from them into your heart. In which case you have plenty of other problems besides.

[1]I have before. It was weird.
[2]Had a dead battery once in college and got a jump from a doctor. He gave me the same electrocution warning. And he should know, because he's a doctor. I didn't argue because I wanted to get home.

[rsisk]

If there was a short with the frame, does this mean the frame isolation test during inspection was not done?

Or would this happen even if the frame isolation test passed?

[Jaci]

Originally Posted by rsisk

If there was a short with the frame, does this mean the frame isolation test during inspection was not done?

Or would this happen even if the frame isolation test passed?

It is possible even if circuits are electrically isolated from the frame before the match. If the outer shielding of the wire (or a solder joint, or wire crimp) becomes damaged, it is very possible for it to contact the robot chassis. With the rigors of Stronghold, this is entirely within the realm of possibility.

[GaryVoshol]

Originally Posted by Jaci

It is possible even if circuits are electrically isolated from the frame before the match. If the outer shielding of the wire (or a solder joint, or wire crimp) becomes damaged, it is very possible for it to contact the robot chassis. With the rigors of Stronghold, this is entirely within the realm of possibility.

From talking with some inspectors, that is the theory. The wire that caught fire went around a corner on a frame piece, and it is suspected that the insulation wore through because of robot movement.

In addition there were some other factors that may or may not have come into play. There may be a suggestion made on additional safety tests in inspection, or a change in wiring rules. I don't want to be more specific in case I am wrong.

[Ben Wolsieffer]

Thinking about this now, I realize that something like this could have happened to us. We had a almost unmeasurable frame short (later discovered to probably caused by a limit switch wire connected to a Talon SRX), which passed inspection because the resistance was higher than the required limit.

Last night and this morning we fried two Talon SRXes, and after a ton of troubleshooting we discovered that our LED ring power cable was being pinched and sometimes connecting positive to the frame. If the resistance was a little lower, I think the same thing could have happened to us. This appeared to be what destroyed the Talons.

[Jon Stratis]

Originally Posted by rsisk

If there was a short with the frame, does this mean the frame isolation test during inspection was not done?

Or would this happen even if the frame isolation test passed?

There's a lot of variables that can go into this, we can't say for certain if it was or was not done. It's possible it was done, but after the fact the insulation wore through. It's possible the frame short was intermittent, and only occurred when a wire was pinched in a mechanism a specific way. Or the team was doing a hasty repair and pinched a wire, or drilled through the insulation of a wire, or disconnected a motor and had the leads just dangling... There are any number of ways for the frame to short out either before or after a frame isolation test is done. And most of the time the frame isolation test is not performed during reinspection.

The reason we do the frame isolation test is to ensure that it takes two faults to cause a problem, not just one. Two faults obviously can still happen, but it's half as likely to happen as having one fault.

[jvriezen]

Originally Posted by Jon Stratis

wo faults obviously can still happen, but it's half as likely to happen as having one fault.

Is this true? If the likelihood of one fault occuring is 1/100, then the like likelihood of two at the same time is 1/10000.

[Analog]

See pic

[Koko Ed]

Originally Posted by Analog

See pic

Best Pit Prank ever!