Go to Post I think it's pretty cool that the Black Eyed Peas and other celebrities are willing to take up their time to come celebrate science and technology with us. - BIGWILLI2081 [more]
Home
Go Back   Chief Delphi > Technical > Electrical
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rating: Thread Rating: 3 votes, 5.00 average. Display Modes
  #1   Spotlight this post!  
Unread 13-05-2015, 11:17
NWChen's Avatar
NWChen NWChen is offline
Alum
no team
 
Join Date: Oct 2012
Rookie Year: 2012
Location: New York City
Posts: 205
NWChen is a splendid one to beholdNWChen is a splendid one to beholdNWChen is a splendid one to beholdNWChen is a splendid one to beholdNWChen is a splendid one to beholdNWChen is a splendid one to beholdNWChen is a splendid one to behold
Custom power distribution

I'm working on a simple power distribution layout with 3 Victors in low-load applications, powered by a 12V SLA battery like this one. To do so (without using the full-scale FRC control system), I'm connecting the motor controllers in parallel to a terminal block. A 4th load will be powered through one of the old 12V-5V converters, also hooked up to the parallel circuit. I've attached images of the circuit below.

Full circuit, without 12V-5V converter
Terminal block closeup

Is there any way that this circuit can damage any of the hardware (especially the Victors)?
__________________
2012 - 2015 • Team 2601


Last edited by NWChen : 13-05-2015 at 11:24.
  #2   Spotlight this post!  
Unread 13-05-2015, 13:05
philso philso is offline
Mentor
FRC #2587
 
Join Date: Jan 2011
Rookie Year: 2011
Location: Houston, Tx
Posts: 940
philso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond repute
Re: Custom power distribution

I am assuming that you are working on something other than an FRC robot.

It would be best if you could insert a fuse between the battery and the terminal block. Those batteries can source enough current to do some damage if there is a short circuit in your system. Choose the fuse rating to be 125% of the total expected current, or the next higher available rating. You may still have to go up a size or two if the expected current is low. The motor controllers will consume some current even when they do not have a load connected. If the total current is less than 10A, you can use an inline fuse holder like the one linked below. They are available at Radio Shack and auto parts stores.

http://www.radioshack.com/10-amp-inl...1.html#start=1

It would be best if you replaced the un-insulated crimp lugs with insulated crimp lugs. The positive and negative lugs are pretty close together and it would be easy to short them together. The bottom of the two lugs can be flipped over so the two lugs do not have to splay apart. You may also want to change how much insulation you strip off the wires. The two red wires at the lower left of the second picture are too short. The single black wire at the right is a bit too long. The single red wire, second from the right, is about the correct length. Make sure you do a pull test after making each crimp.
  #3   Spotlight this post!  
Unread 13-05-2015, 13:16
brycen66 brycen66 is offline
Registered User
FRC #1678 (Citrus Circuits)
Team Role: Electrical
 
Join Date: Jan 2013
Rookie Year: 2011
Location: United States
Posts: 34
brycen66 is just really nicebrycen66 is just really nicebrycen66 is just really nicebrycen66 is just really nice
Re: Custom power distribution

Is that a breaker or a switch in the bottom left corner? Also what gauge of wire are you using?

The idea is safe as long as you are using properly sized wire. Three victors should pull less than 30 amps continuously, although they may spike higher. So for that setup I would use 14 gauge for downstream (12 in enclosed spaces) and probably 8 gauge for up stream (6 in enclosed spaces). And a properly sized breaker (80-100 amps)

It looks like you may be using 12-14 gauge for the whole thing, that's probably not big enough.
That being said I have powered three motors off of 12 gauge before in a pinch, and have destroyed wires. But if you are only running it for a short time, don't mind smoke, and have a fire extinguisher nearby, you can probably get away with this setup and it probably wont do anything too bad. But I wouldn't recommend it.
  #4   Spotlight this post!  
Unread 13-05-2015, 13:43
PAR_WIG1350's Avatar
PAR_WIG1350 PAR_WIG1350 is offline
Registered User
AKA: Alan Wells
FRC #1350 (Rambots)
Team Role: Alumni
 
Join Date: Dec 2009
Rookie Year: 2009
Location: Rhode Island
Posts: 1,190
PAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond repute
Re: Custom power distribution

Breaker/fuse size should be selected based on the wire used, not the expected current draw. Overcurrent protection is used primarily to prevent the wires from overheating and setting things on fire. If you follow the FRC robot rules for matching wire gauge to fuse/breaker rating, then you should be safe.

If you use a single fuse or breaker, it should go between the battery and the terminal block. In this configuration, all wires should be appropriately sized for the rated current of the fuse/breaker.
If you put a fuse/breaker on each branch, then the wires between the battery and the terminal block should be sized to handle the sum of the rated currents.
__________________

Last edited by PAR_WIG1350 : 13-05-2015 at 13:45.
  #5   Spotlight this post!  
Unread 13-05-2015, 14:17
PAR_WIG1350's Avatar
PAR_WIG1350 PAR_WIG1350 is offline
Registered User
AKA: Alan Wells
FRC #1350 (Rambots)
Team Role: Alumni
 
Join Date: Dec 2009
Rookie Year: 2009
Location: Rhode Island
Posts: 1,190
PAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond repute
Re: Custom power distribution

Quote:
Originally Posted by brycen66 View Post
Is that a breaker or a switch in the bottom left corner? Also what gauge of wire are you using?

The idea is safe as long as you are using properly sized wire. Three victors should pull less than 30 amps continuously, although they may spike higher. So for that setup I would use 14 gauge for downstream (12 in enclosed spaces) and probably 8 gauge for up stream (6 in enclosed spaces). And a properly sized breaker (80-100 amps)

It looks like you may be using 12-14 gauge for the whole thing, that's probably not big enough.
That being said I have powered three motors off of 12 gauge before in a pinch, and have destroyed wires. But if you are only running it for a short time, don't mind smoke, and have a fire extinguisher nearby, you can probably get away with this setup and it probably wont do anything too bad. But I wouldn't recommend it.
The text that I made bold above is not quite accurate. The current draw of three victors is indeed far less than 30A, but one must realize that the current draw of a victor isn't nearly as important as the current draw of the device on the other side of the victor. For example, at their rated "maximum efficiency" condition, 3 CIMs should draw ~60 amps continuously (and 81 amps under "normal load" conditions). At stall, the same motors draw a combined 399 amps. This is why the breakers used on FRC robots, and Victors, are designed to be relatively tolerant of overcurrent conditions.

I would recommend using the same breakers used in the PDP since history shows that they do a good job of protecting victors while still allowing for the large current spikes that occur with powerful motors.
__________________
  #6   Spotlight this post!  
Unread 13-05-2015, 14:19
FrankJ's Avatar
FrankJ FrankJ is offline
Robot Mentor
FRC #2974 (WALT)
Team Role: Mentor
 
Join Date: Feb 2011
Rookie Year: 2009
Location: Marietta GA
Posts: 1,946
FrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond repute
Re: Custom power distribution

Quote:
Originally Posted by PAR_WIG1350 View Post
Breaker/fuse size should be selected based on the wire used, not the expected current draw. Overcurrent protection is used primarily to prevent the wires from overheating and setting things on fire. ....
That is really building wiring philosophy or for situations where you don't know what the downstream loads are going to be. The assumption there is the machine designer will design his equipment to handle the over current. Even there I have downsized breakers to match the equipment where I specified over size wiring because of the voltage drop. In machinery where you know the current demands, good practice is to size the fuses for the load. Cars are a good example of this.

A little late now, but you can buy fuse blocks so you can individually fuse the circuits. ATC style fuse blocks can be had for cheap. Cross the Road recomends strongly that their motor controller have circuit protection.
__________________
If you don't know what you should hook up then you should read a data sheet
  #7   Spotlight this post!  
Unread 13-05-2015, 14:22
Andrew Schreiber Andrew Schreiber is offline
Joining the 900 Meme Team
FRC #0079
 
Join Date: Jan 2005
Rookie Year: 2000
Location: Misplaced Michigander
Posts: 4,079
Andrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond repute
Re: Custom power distribution

Quote:
Originally Posted by FrankJ View Post
That is really building wiring philosophy or for situations where you don't know what the downstream loads are going to be. The assumption there is the machine designer will design his equipment to handle the over current. Even there I have downsized breakers to match the equipment where I specified over size wiring because of the voltage drop. In machinery where you know the current demands, good practice is to size the fuses for the load. Cars are a good example of this.

A little late now, but you can buy fuse blocks so you can individually fuse the circuits. ATC style fuse blocks can be had for cheap. Cross the Road recomends strongly that their motor controller have circuit protection.
Something a friend from 193 and I have been tinkering with is putting together parts lists for smaller custom robots: Yesterday we were doing the power distribution parts so why not share...

http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

They will take the FRC fuses (up to 30A, recall this is small) and are pretty low cost.
__________________




.
  #8   Spotlight this post!  
Unread 13-05-2015, 15:33
MrRoboSteve MrRoboSteve is offline
Mentor
AKA: Steve Peterson
FRC #3081 (Kennedy RoboEagles)
Team Role: Mentor
 
Join Date: Mar 2012
Rookie Year: 2011
Location: Bloomington, MN
Posts: 582
MrRoboSteve has a reputation beyond reputeMrRoboSteve has a reputation beyond reputeMrRoboSteve has a reputation beyond reputeMrRoboSteve has a reputation beyond reputeMrRoboSteve has a reputation beyond reputeMrRoboSteve has a reputation beyond reputeMrRoboSteve has a reputation beyond reputeMrRoboSteve has a reputation beyond reputeMrRoboSteve has a reputation beyond reputeMrRoboSteve has a reputation beyond reputeMrRoboSteve has a reputation beyond repute
Re: Custom power distribution

Thanks for the pointer -- I hadn't seen something like that before.

I was looking through the 2015 rules, and it seems like they would be legal for FRC use as part of a "custom circuit", for example to put a bunch of low-load custom circuits on one PDB circuit.
__________________
2016-17 events: 10000 Lakes Regional, Northern Lights Regional, FTC Burnsville Qualifying Tournament

2011 - present · FRC 3081 Kennedy RoboEagles mentor
2013 - present · event volunteer at 10000 Lakes Regional, Northern Lights Regional, North Star Regional, Lake Superior Regional, Minnesota State Tournament, PNW District 4 Glacier Peak, MN FTC, CMP
http://twitter.com/MrRoboSteve · www.linkedin.com/in/speterson
  #9   Spotlight this post!  
Unread 13-05-2015, 16:11
PAR_WIG1350's Avatar
PAR_WIG1350 PAR_WIG1350 is offline
Registered User
AKA: Alan Wells
FRC #1350 (Rambots)
Team Role: Alumni
 
Join Date: Dec 2009
Rookie Year: 2009
Location: Rhode Island
Posts: 1,190
PAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond reputePAR_WIG1350 has a reputation beyond repute
Re: Custom power distribution

Quote:
Originally Posted by FrankJ View Post
That is really building wiring philosophy or for situations where you don't know what the downstream loads are going to be. The assumption there is the machine designer will design his equipment to handle the over current. Even there I have downsized breakers to match the equipment where I specified over size wiring because of the voltage drop. In machinery where you know the current demands, good practice is to size the fuses for the load. Cars are a good example of this.

A little late now, but you can buy fuse blocks so you can individually fuse the circuits. ATC style fuse blocks can be had for cheap. Cross the Road recomends strongly that their motor controller have circuit protection.
Given that the current draw of the loads(motors?) connected to the victors was not given, I assumed that it was not known.
__________________
  #10   Spotlight this post!  
Unread 13-05-2015, 17:05
jee7s jee7s is offline
Texan FIRSTer, ex-frc2789, ex-frc41
AKA: Jeffrey Erickson
FRC #6357
 
Join Date: Nov 2007
Rookie Year: 1997
Location: Dripping Springs, TX
Posts: 319
jee7s has a reputation beyond reputejee7s has a reputation beyond reputejee7s has a reputation beyond reputejee7s has a reputation beyond reputejee7s has a reputation beyond reputejee7s has a reputation beyond reputejee7s has a reputation beyond reputejee7s has a reputation beyond reputejee7s has a reputation beyond reputejee7s has a reputation beyond reputejee7s has a reputation beyond repute
Re: Custom power distribution

Quote:
Originally Posted by PAR_WIG1350 View Post
Given that the current draw of the loads(motors?) connected to the victors was not given, I assumed that it was not known.
Moreover, the protection devices need to be sized to prevent an unsafe condition if there is a failure (i.e. a motor fails short, terminal block is shorted, etc). So, you can pick a wire gauge and size the fuse to it, then pick the load (but the load may not be able to draw all the current it wants or needs to). Or, you can pick a load, size the fuse to that, then select the wire gauge based on the fuse (so the load can draw all the current required). The former is often the case in FRC. The latter is the more real-world design methodology.

Really, your earlier statement about sizing the fuse to the wire encapsulates the broader idea that if a failure occurs the elements of the system need to mitigate the failure so that an unsafe condition is not reached. That safety concern is primarily thermal (not having a fire, preventing the insulation from melting, etc), but can also deal with other areas (like protecting the battery). In many cases the mitigation means a fuse, but there are other mechanisms (like foldback circuits) that can be used to prevent the unsafe condition due to too much current draw.

The simpliest for this application is probably the inline circuit breaker or fuse between the terminal block and battery that has been previously mentioned.
__________________

2013 Alamo Regional Woodie Flowers Finalist Award Winner
2012 Texas Robot Roundup Volunteer of the Year
Texas Robot Roundup Planning Committee, 2012-present
FRC 6357 Mentor, 2016-
FRC 2789 Mentor, 2009-2016 -- 2 Golds, 2 Silvers, 8 Regional Elimination Appearances

FRC 41 Mentor 2007-2009
FLL Mentor 2006
FRC 619 Mentor 2002
FRC 41 Student 1998-2000

Last edited by jee7s : 13-05-2015 at 17:09. Reason: Typos and clarification
  #11   Spotlight this post!  
Unread 13-05-2015, 17:29
FrankJ's Avatar
FrankJ FrankJ is offline
Robot Mentor
FRC #2974 (WALT)
Team Role: Mentor
 
Join Date: Feb 2011
Rookie Year: 2009
Location: Marietta GA
Posts: 1,946
FrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond reputeFrankJ has a reputation beyond repute
Re: Custom power distribution

Quote:
Originally Posted by PAR_WIG1350 View Post
Given that the current draw of the loads(motors?) connected to the victors was not given, I assumed that it was not known.
Several approaches to this. Fuses only trip once. That can be annoying and or useful. So for a fuse I would size it either at or somewhat over the motor stall current. For motor I would use a slow blow fuse. A lot depends on the inertial load. For a self resetting breaker closer to the actual motor load. In any case I would size it to protect the motor controller.
__________________
If you don't know what you should hook up then you should read a data sheet
  #12   Spotlight this post!  
Unread 13-05-2015, 17:43
Nate Laverdure's Avatar
Nate Laverdure Nate Laverdure is offline
Registered User
FRC #2363
Team Role: Coach
 
Join Date: Apr 2005
Rookie Year: 1999
Location: Newport News, VA
Posts: 834
Nate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond reputeNate Laverdure has a reputation beyond repute
Re: Custom power distribution

Quote:
Originally Posted by Andrew Schreiber View Post
All the Blue Sea Systems stuff is just perfect. Almost makes me want to buy a boat.
  #13   Spotlight this post!  
Unread 13-05-2015, 18:37
philso philso is offline
Mentor
FRC #2587
 
Join Date: Jan 2011
Rookie Year: 2011
Location: Houston, Tx
Posts: 940
philso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond reputephilso has a reputation beyond repute
Re: Custom power distribution

Hey NWChen

Please clarify what you mean when you say you are using the "3 Victors in low-load applications". Please also state what wire size you are using.


The current draw of the motor control controllers is the load current plus some small quiescent current. I doubt that the OP would consider 30A per Victor a low-load application.

If the OP is running small motors that only draw a few amps in a non-FRC application, then selecting the fuses to protect the load is a valid way to go. From the photos, it looks like he is already using 14AWG or 12AWG wire which would be more than enough for a few amps.

The fuse holder Andrew linked to with resettable breakers would be a nice touch but the breakers might not be available in ratings that are low enough. The Blue Sea bus bars are nice too but the terminal blocks he is using would also be just fine. We use many of those in the equipment we build at work.
  #14   Spotlight this post!  
Unread 13-05-2015, 19:26
Andrew Schreiber Andrew Schreiber is offline
Joining the 900 Meme Team
FRC #0079
 
Join Date: Jan 2005
Rookie Year: 2000
Location: Misplaced Michigander
Posts: 4,079
Andrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond reputeAndrew Schreiber has a reputation beyond repute
Re: Custom power distribution

Quote:
Originally Posted by philso View Post
Hey NWChen

Please clarify what you mean when you say you are using the "3 Victors in low-load applications". Please also state what wire size you are using.


The current draw of the motor control controllers is the load current plus some small quiescent current. I doubt that the OP would consider 30A per Victor a low-load application.

If the OP is running small motors that only draw a few amps in a non-FRC application, then selecting the fuses to protect the load is a valid way to go. From the photos, it looks like he is already using 14AWG or 12AWG wire which would be more than enough for a few amps.

The fuse holder Andrew linked to with resettable breakers would be a nice touch but the breakers might not be available in ratings that are low enough. The Blue Sea bus bars are nice too but the terminal blocks he is using would also be just fine. We use many of those in the equipment we build at work.
The fuse holder was chosen because I'm FAIRLY certain it will work with FRC style Snap-On resettable fuses. And those are available from 5-40A (though the holder is only rated for 30A per branch. I'll let you know if this is true on Friday when one is delivered.

I assumed the terminal block he's using was fine, I just linked the bus bar in case anyone was looking for something like it. (And I was hoping someone else would do a sanity check on if it would work for smaller than FRC applications)
__________________




.
  #15   Spotlight this post!  
Unread 13-05-2015, 20:03
NWChen's Avatar
NWChen NWChen is offline
Alum
no team
 
Join Date: Oct 2012
Rookie Year: 2012
Location: New York City
Posts: 205
NWChen is a splendid one to beholdNWChen is a splendid one to beholdNWChen is a splendid one to beholdNWChen is a splendid one to beholdNWChen is a splendid one to beholdNWChen is a splendid one to beholdNWChen is a splendid one to behold
Re: Custom power distribution

Quote:
Originally Posted by philso View Post
Please clarify what you mean when you say you are using the "3 Victors in low-load applications". Please also state what wire size you are using.
The circuit pictured uses 16AWG wire (oops).
The loads on the Victors are an RS775 in a 1:188 gearbox, a Globe Motor, and a Denso window motor. Each motor (with the exception of the Globe, for which I couldn't find a performance curve) is drawing no more than ~10A.

Quote:
Originally Posted by Andrew Schreiber View Post
I just linked the bus bar in case anyone was looking for something like it. (And I was hoping someone else would do a sanity check on if it would work for smaller than FRC applications)
Thanks Andrew - recommended parts lists for smaller robots would be pretty helpful.
__________________
2012 - 2015 • Team 2601


Last edited by NWChen : 13-05-2015 at 20:06.
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 20:37.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi