*Warning* On talons!!!!

[Ether]

Originally Posted by Cory

You should have had a breaker inline to protect the talon from extended over-current.

I believe CTRE has tested the Talon and it is capable of handling just about anything the 40 amp breaker is capable of throwing at it, as long as the fan is attached. Mike C please correct me if I have misrepresented that.

[Jon Stratis]

Unfortunately, there aren't numbers available for the Victor 888 (the website says "Update Coming Soon", last time I checked). But some specs to compare:

Jaguar:
Continuous current: 40A
2 second current: 60A
peak at startup: 100A
Source: http://content.vexrobotics.com/docs/..._Datasheet.pdf

Talon:
Up to 100 amps peak 60 amps continuous current.
Source: http://www.crosstheroadelectronics.c...Manual_1_2.pdf

The Talon really isn't any different from the other speed controllers, and you'll only risk blowing one if you design something poorly (like a CIM motor that's constantly stalled). We've used Jaguars for years on our drive train, and never blown one, I don't expect to see anything different from the Talon.

Originally Posted by Cory

You should have had a breaker inline to protect the talon from extended over-current.

The breaker is present to protect the wiring, not the components attached to it.

[Tom Line]

We ran a talon with fan in a drive train stalled and pulled a continuous 78 amps by using multiple 40amp breaker inputs with no problem for extended periods of time during our beta testing.

An FRC robot should have a 40 amp snap action breaker that should not allow the Talon or Any Other motor controller to see 100 amps continuously for any amount of time.

Can you please detail your robot setup to show us how you pulled 100 amps long enough to damage the Talon?

[Jorge Ayala]

My team has been using Talons for a while, some months before the kickoff and so far any problems have been noticed. Actually, we did have some problems with Jaguars before using Talons.

[Ether]

Originally Posted by Jon Stratis

The Talon really isn't any different from the other speed controllers, and you'll only risk blowing one if you design something poorly (like a CIM motor that's constantly stalled).

See my previous post.

[tomy]

The point of this thread was to get the knowledge out there to be careful

[EricVanWyk]

Originally Posted by tomy

The point of this thread was to get the knowledge out there to be careful

Yes, but the "knowledge" is incorrect, misleading and poorly communicated.

Please do not spread Fear/Uncertainty/Doubt without evidence.

[Tom Line]

Originally Posted by tomy

The point of this thread was to get the knowledge out there to be careful

I am still very confused about what we should be careful of. Used correctly, none of the first motor controllers will ever see that amount of current long enough to damage them.

[mikeleslie]

So what I'm reading is that according to the spec, you should be careful using a Talon on an unprotected circut, so don't connect directly to the battery on one side with a CIM locked in a vice on the other.
Just testing my underastanding of the issue...
Of course if you wired things up similar to what's shown in the rulebook, you would have 2 breakers, both of which should go long before the Talon.

[Cory]

Originally Posted by Jon Stratis

The breaker is present to protect the wiring, not the components attached to it.

I understand that, but as a result, the Talon should never be able to see 133A.

[dyanoshak]

Originally Posted by Cory

I understand that, but as a result, the Talon should never be able to see 133A.

The snap action breakers trip based on heat. Short spikes of high current still make it through before the breaker heats up to the trip point.

Even with a breaker in place, you can still damage a motor controller with excessive current (e.g. a short circuit). The breakers simply can't react fast enough to save the components in certain situations. That is why "breakers are for preventing fires, not saving the components."

Breakers do play a role in component safety, but they need to be used in conjunction with proper electrical design. When using a motor controller...

• that is wired correctly
• with fans when necessary
• with breakers installed
• with well designed mechanisms (to reduce the chance of stalling a motor)
• etc.

you shouldn't see any failures.

-David

[s1900ahon]

Cory,

David points out that short spikes of current will get through..

Check out the circuit breaker spec here. As you can see, a 40A circuit breaker will allow 500% (200A) to pass for 0.2 to 0.3s before tripping.

-Scott

[Ether]

Originally Posted by s1900ahon

As you can see, a 40A circuit breaker will allow 500% (200A) to pass for 0.2 to 0.3s before tripping.

Are you implying that 200A for 0.3 seconds will damage a Talon (or a Victor)? If so, would you please tell us where you got that info? Thank you.

[dyanoshak]

Emphasis on can damage.

I have personally caused a Jaguar failure by connecting a dead short across the motor terminals. This was in early Jaguar testing 3-4 years ago.

I haven't personally caused a failure with the others.

Scott and I aren't implying that certain exact conditions will or will not damage any of the motor controllers. We're trying stop a common misconception that the breakers instantaneously trip once you go over 40A. They take time, and can't be guaranteed to protect anything but the wiring.

-David

[Ether]

Originally Posted by dyanoshak

Scott and I aren't implying that certain exact conditions will or will not damage any of the motor controllers. We're trying stop a common misconception that the breakers instantaneously trip once you go over 40A. They take time, and can't be guaranteed to protect anything but the wiring.

Understood. But there's a flip side to that coin, to wit:

Assuming the datasheet specs for the 40 amp breaker can be trusted, it's possible to design a product around those specs so that the breaker WILL protect it.

Hence the question: what are the chances of damaging, say, a Talon, if it is properly wired and protected by a properly operating in-spec 40 amp FRC breaker?

I wouldn't lose any sleep over it.