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-   -   Looking for slip rings and distributors (http://www.chiefdelphi.com/forums/showthread.php?t=130622)

sanelss 22-09-2014 17:14
Looking for slip rings and distributors
 
Our team is attempting to do swerve drive this year and we are looking for some slip rings but having troubles finding appropriate ones. we need 2 40A lines for a cim and 3 signal lines.

What slip rings does your team use(if any) and where do you get them from?

Mk.32 22-09-2014 18:20
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by sanelss (Post 1401085)
Our team is attempting to do swerve drive this year and we are looking for some slip rings but having troubles finding appropriate ones. we need 2 40A lines for a cim and 3 signal lines.

What slip rings does your team use(if any) and where do you get them from?
I have used these on non-FRC related projects with great suceess: http://www.mercotac.com/html/430.html

Chadfrom308 22-09-2014 18:38
Re: Looking for slip rings and distributors
 
Adafruit has 2 amp ones that you can run PWM cable through, that might be helpful if you can modify your design a little

sanelss 22-09-2014 18:39
Re: Looking for slip rings and distributors
 
the only unit they have that meets our needs is the model 830. Why do they not list prices???? I imagine they will be 100+ each but if they are too much more than that may be an issue.

sanelss 22-09-2014 18:40
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by Chadfrom308 (Post 1401097)
Adafruit has 2 amp ones that you can run PWM cable through, that might be helpful if you can modify your design a little
for the servo no problem, but we still need 2 40 amp channels for the cim and if we are to use a secondary slip ring the cim slip rings needs to be a through hole style.

Mk.32 22-09-2014 19:11
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by sanelss (Post 1401098)
the only unit they have that meets our needs is the model 830. Why do they not list prices???? I imagine they will be 100+ each but if they are too much more than that may be an issue.
As with most suppliers you have to contact them for a price:
http://www.mercotac.com/html/purchasing.html
Contact info at the bottom, they are local to me so I just drive over and pick stuff up.

These are expensive, have you thought about designing your swerve so it is independent like 1717/others?

Peyton Yeung 22-09-2014 19:57
Re: Looking for slip rings and distributors
 
I believe Bomb Squid :cool: (Team 16) uses slip rings in their swerve. You might try contacting one of them.

artdutra04 22-09-2014 20:03
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by sanelss (Post 1401085)
Our team is attempting to do swerve drive this year and we are looking for some slip rings but having troubles finding appropriate ones. we need 2 40A lines for a cim and 3 signal lines.
Even through CIM motors are usually on 40A breakers, they can draw significantly more current for brief periods of time. The breakers do not trip instantly at 40.00001A, they trip after X seconds depending on the ambient temperature and current being drawn. Thus, your slip rings should be rated to handle the stall current of a CIM motor.

Mk.32 22-09-2014 21:10
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by artdutra04 (Post 1401107)
Even through CIM motors are usually on 40A breakers, they can draw significantly more current for brief periods of time. The breakers do not trip instantly at 40.00001A, they trip after X seconds depending on the ambient temperature and current being drawn. Thus, your slip rings should be rated to handle the stall current of a CIM motor.
I don't think you need slip rings that can handle stall current of a CIM those would be pretty insane 180amps? .... Just like the breakers I am sure the slip rings aren't going to melt at 40.00001 amps. I would contact the manufacture for a more detailed answer on what they can handle.

Bomb squad if I remember correctly uses one of the Mercotac models...

Aren Siekmeier 22-09-2014 22:10
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by artdutra04 (Post 1401107)
Even through CIM motors are usually on 40A breakers, they can draw significantly more current for brief periods of time. The breakers do not trip instantly at 40.00001A, they trip after X seconds depending on the ambient temperature and current being drawn. Thus, your slip rings should be rated to handle the stall current of a CIM motor.
The 12 gauge wiring required by FRC rules for circuits on 40A breakers is also only rated for ~40A. The breaker is designed to trip in a way that reflects how the wiring is heating up. I imagine the conductors in a slip ring have similar behavior and can be similarly rated and protected by the breaker. Basically, if the wiring only needs a 40A rating (130A would require 4 gauge wire...), then a slip ring should be fine with that as well. Please correct me if this reasoning doesn't work.

Can someone chime in on any differences between these parts of the circuit and their current ratings?

cgmv123 22-09-2014 22:23
Re: Looking for slip rings and distributors
 
The 2014 robot rules allow slip rings as part of branch circuits "as long as the entire electrical pathway is via appropriately gauged/rated elements." Since a branch circuit is rated for 40 amps and 12/10 AWG wire, the slip ring should be rated accordingly.

asid61 23-09-2014 01:28
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by cgmv123 (Post 1401119)
The 2014 robot rules allow slip rings as part of branch circuits "as long as the entire electrical pathway is via appropriately gauged/rated elements." Since a branch circuit is rated for 40 amps and 12/10 AWG wire, the slip ring should be rated accordingly.
Link to source? I have been looking for legality stuff on slip rings for a while, but I couldn't find anything on the Q&A or in the official rules, other than that custom circuits are prohibited.

Also, bomb squad uses the Mercotac Model 230 slip ring according to a PM I got a while back. They're ~$100 each online it looks like.

sanelss 23-09-2014 02:22
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by Mk.32 (Post 1401102)
As with most suppliers you have to contact them for a price:
http://www.mercotac.com/html/purchasing.html
Contact info at the bottom, they are local to me so I just drive over and pick stuff up.

These are expensive, have you thought about designing your swerve so it is independent like 1717/others?
independent? not sure what you mean here. can you elaborate?

sanelss 23-09-2014 02:24
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by artdutra04 (Post 1401107)
Even through CIM motors are usually on 40A breakers, they can draw significantly more current for brief periods of time. The breakers do not trip instantly at 40.00001A, they trip after X seconds depending on the ambient temperature and current being drawn. Thus, your slip rings should be rated to handle the stall current of a CIM motor.
we can't even find slip rings rated for 40A much less the hundreds of amps stall current. those things would be the size of a truck. and i imagine slip rings can also handle higher peaks as well anyway, i'm just trying to get as close numbers based on continuous ratings as I can.

asid61 23-09-2014 02:27
Re: Looking for slip rings and distributors
 
Quote:
Originally Posted by sanelss (Post 1401133)
independent? not sure what you mean here. can you elaborate?
Like, able to rotate freely without the cim. Essentially, outsource all wires to areas outside the rotating module.


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