View Full Version : More than one power distribution board
BEN35678
24-01-2014, 21:58
Is it legal to have more than one power distribution board?
z_beeblebrox
24-01-2014, 22:07
R35:
The one ROBOT battery, Anderson Power Products (or APP) Connectors (p/n SB50), the one main 120-amp (120A) circuit breaker (Cooper Bussman P/N: CB185-120), and the one Power Distribution (PD) Board shall be connected as shown in Figure 4-11 (http://frc-manual.usfirst.org/upload/images/2014/1/Figure4-11.jpg).
kevin.li.rit
24-01-2014, 22:14
So what rule would prohibit him from hooking up the 2nd PD board via a 40 AMP breaker slot?
Not that I'm suggesting it or that it'd would be useful (since you wouldn't be able to attach anything to it per r51 either).
So what rule would prohibit him from hooking up the 2nd PD board via a 40 AMP breaker slot?
Not that I'm suggesting it or that it'd would be useful.
If pressed, and depending on the exact setup, I could probably justify dinging him on an R53 violation (custom circuits shall not directly alter the power pathways--this is a pretty massive branch circuit that routes power Battery->Breaker->PD Main->PD Secondary->OTHER circuits). Possibly, depending what all was connected to the 2nd board, a safety issue as well.
The counter to this is the R44 blue box--you'd be doing a multi-point distribution of circuit power, and each circuit just happens to have its own breaker, which last is allowed. (BTW, Ben, if you're running out of slots, take a good look at the blue box and see if you can't figure out a legal way to take advantage of its provisions.)
On the other hand, the word "THE" is used an awful lot with respect to PD boards on the robot. "The" is a singular word...
Al Skierkiewicz
25-01-2014, 23:44
One and only one please per R35. The battery and wiring can only deliver so much current before parts start to fail.
Is there any chance I can volunteer to make a better power power distribution board for FRC? The provided one has less-than-deluxe connectors and is huge compared to what it accomplishes. I'm an electrical engineer and have built plenty of battery distribution hardware for the automotive industry.
The last time I tried to contact FRC about making a nice piece of hardware for the kit of parts I never got a response. Presumably there's a better contact address than the info link on the website?
amesmich
26-01-2014, 08:53
The provided one has less-than-deluxe connectors and is huge compared to what it accomplishes.
I am in full agreement.
Have there been any failures or problems that would justify the cost of a redesign? We have no problems withe PDB.
Next year, with the new control system we'll be getting a small power distribution board.
I agree with the connectors part, those WAGO things are awful, but I do like the current board. You get three really solid power supplies(5, 12, 24 V) that won't drop out, even at super low voltage. It's way better than the old one where you had to use a backup battery that you had to either get the charging thing for it, or remember to charge it before your matches. It was not a great solution.
tr6scott
26-01-2014, 10:03
http://www.fightingpi.org/Resources/Controls/Alpha/2015_Alpha/Power%20Distribution%20Panel.shtml
Fighting Pi has alpha data on the 2015 PDB if interested.
Cross the Road E is developing.
Alan Anderson
26-01-2014, 16:41
The provided one has less-than-deluxe connectors...
I agree with the connectors part, those WAGO things are awful...
What specifically do you think is wrong with the Wago connectors? I find them amazingly convenient, capable, and reliable.
SoftwareBug2.0
26-01-2014, 21:16
What specifically do you think is wrong with the Wago connectors? I find them amazingly convenient, capable, and reliable.
It requires a specialized tool to use and the intuitive way to use that tool is likely to break something.
geomapguy
26-01-2014, 21:20
It requires a specialized tool to use and the intuitive way to use that tool is likely to break something.
You can just use a flathead screwdriver
It requires a specialized tool to use and the intuitive way to use that tool is likely to break something.
We have abused ours pretty well for several years and never broken one.
geomapguy
26-01-2014, 21:30
We have abused ours pretty well for several years and never broken one.
Is there really a WAGO tool????
Christopher149
26-01-2014, 21:31
I think we managed to break one WAGO connector once.
To the OP: why would you want a second board? Have you run out of breaker slots or something?
Is there really a WAGO tool????
Yeah, here is one on amazon (http://www.amazon.com/gp/aw/d/B00009OYGV)
Dang, there actually is one: WAGO (hhttp://www.newark.com/wago/210-719/terminal-block-operating-tool/dp/51R1951?MER=ACC_N_L5_Tools_None)
Looks like an insulated electricians screwdriver...
Christopher149
26-01-2014, 22:15
Yeah, here is one on amazon (http://www.amazon.com/gp/aw/d/B00009OYGV)
Dang, there actually is one: WAGO (hhttp://www.newark.com/wago/210-719/terminal-block-operating-tool/dp/51R1951?MER=ACC_N_L5_Tools_None)
Looks like an insulated electricians screwdriver...
I remember having one with a white, cylindrical handle with WAGO printed on. We lost it a couple years ago.
I remember having one with a white, cylindrical handle with WAGO printed on. We lost it a couple years ago.
They must have come in the kit at some point. We have one exactly like that as well. I find it much much easier to use than a flathead screwdriver; prolly the angles on it.
I remember having one with a white, cylindrical handle with WAGO printed on. We lost it a couple years ago.
Both of my teams lost ours during their rookie years...
Alan Anderson
26-01-2014, 22:34
The only thing specialized about the official Wago tool is the slippery coating that makes it a tiny bit easier to use than a standard small screwdriver. I typically use the kind that's often given away as a promotional item. (We're actually using a ground-down right-angle Allen wrench on our PDB this year because of a specific spacing issue in the robot.)
What does "intuitive" mean? Push the tool into the slot and the connector opens up. Pull it back out and the connector closes. I suppose you could break something if you got silly and tried to turn the handle while it was inserted, or if you tried to pry the plastic apart with it, but neither of those seem like an obvious thing to do.
SoftwareBug2.0
26-01-2014, 22:59
The only thing specialized about the official Wago tool is the slippery coating that makes it a tiny bit easier to use than a standard small screwdriver. I typically use the kind that's often given away as a promotional item. (We're actually using a ground-down right-angle Allen wrench on our PDB this year because of a specific spacing issue in the robot.)
What does "intuitive" mean? Push the tool into the slot and the connector opens up. Pull it back out and the connector closes. I suppose you could break something if you got silly and tried to turn the handle while it was inserted, or if you tried to pry the plastic apart with it, but neither of those seem like an obvious thing to do.
By intuitive I mean that if you tell someone to do it with no further instructions they are likely to do it the right way. If people just naturally did it right the warnings on page 9 of this document would not be needed.
http://www.usfirst.org/sites/default/files/uploadedImages/Robotics_Programs/FRC/Game_and_Season__Info/2014/Power_Distribution_Board.pdf
I'm not sure what the per-unit cost targets are, but I tend to use electronic overcurrent circuits. They've gotten remarkably capable and reasonably-priced in recent years. They're also amazingly compact.
I would also like to see an Ethernet switch integrated onto the power distribution board, with 12v and GND going to each pair of magnetic center taps. Then you could use a Ubiquiti Pico- or Nanostation and an Axis PoE-capable camera and get rid of a whole class of wires.
Al Skierkiewicz
27-01-2014, 07:25
I'm not sure what the per-unit cost targets are, but I tend to use electronic overcurrent circuits.
Have you seen something that can protect 40 amp wiring and still function at the 130 amp stall of a CIM for a short period of time?
Isaac501
27-01-2014, 07:32
It requires a specialized tool to use and the intuitive way to use that tool is likely to break something.
Flathead screwdrivers aren't really specialized tools.
We use one small (3mm) for the PDB and a jewelers for the tiny ones for the cRIO and bumpers.
Insert tool, flex retaining clip, insert wire, remove tool. This hasn't broken our connectors or bumpers or boards in the 5 years we've been using it.
I don't think intuition is really a metric you should be caring about here - nothing we use is intuitive. Screwdrivers for some are not intuitive. Your iphone may be more intuitive for some of your students than a screw driver.
Isaac501
27-01-2014, 07:36
By intuitive I mean that if you tell someone to do it with no further instructions they are likely to do it the right way. If people just naturally did it right the warnings on page 9 of this document would not be needed.
http://www.usfirst.org/sites/default/files/uploadedImages/Robotics_Programs/FRC/Game_and_Season__Info/2014/Power_Distribution_Board.pdf
Like anything else in FIRST, using specialized hardware (the PDB) requires learning and mentoring. Since I lead the wiring team, I make sure to show the students the proper method before letting them hurt themselves (possible) or break our parts or tools.
"Just do it" is a recipe for broken hearts and broken hardware. It fosters creativity and learning, absolutely, but at the cost of safety and time/money/resources.
Al Skierkiewicz
27-01-2014, 07:59
Everyone,
One of the biggest errors in terminating to the WAGO connectors is improper stripping of the insulation. WAGO recommends 5/8" to insure good contact inside the terminal. If you do that, and insert the wire so no copper is showing, then you have a good contact with the wire and it will not pull out. Please remember that these terminals are used in production environments and industrial installations. Installers rarely will insert the tool fully, they simply have learned the "feel" of inserting the tool, lifting while inserting the wire and then dropping the tool to lock the wire. While it takes two handed coordination, an experienced installer will take about 1 second for each termination.
What specifically do you think is wrong with the Wago connectors? I find them amazingly convenient, capable, and reliable.
They require a huge tool access space all around the sides. This is hard to package. If everything went up instead of out it would be fine.
They require a huge tool access space all around the sides. This is hard to package. If everything went up instead of out it would be fine.
They don't require much tool access at all if you use something compact, like a custom ground Allen wrench as was mentioned before. We use a small screwdriver with a 45 degree bend in it and we can place our board about an inch or so away from obstacles with no issue.
Have you seen something that can protect 40 amp wiring and still function at the 130 amp stall of a CIM for a short period of time?
Yup. Infineon makes excellent FETs, and Linear Technology makes excellent surge protection control ICs that drive them. BOM cost is a little high at about $8/channel in qty 1 from Digikey (so assume 1/10th that or less at any decent scale). They have capacitors to set the allowable overcurrent time. One of the circuits I built at work hard limits at 180A and is intended for 60A continuous. Consumes a little less than a square inch.
We use this (http://www.newark.com/wago/210-722/terminal-block-operating-tool/dp/51R0264) set of tools from WAGO -- they seem to work much better than a screwdriver and fit all connectors of this type used in FRC.
Al Skierkiewicz
31-01-2014, 09:02
Yup. Infineon makes excellent FETs, and Linear Technology makes excellent surge protection control ICs that drive them. BOM cost is a little high at about $8/channel in qty 1 from Digikey (so assume 1/10th that or less at any decent scale). They have capacitors to set the allowable overcurrent time. One of the circuits I built at work hard limits at 180A and is intended for 60A continuous. Consumes a little less than a square inch.
Part numbers and links please.
So everyone seems to generally like the big WAGO's on the PD board.
Does anyone else totally hate the little white ones? they're used for power to the cRio breakouts and the radio power out on the PD board. My electrical student has a really really hard time doing them, so usually I do all of them for her.
So everyone seems to generally like the big WAGO's on the PD board.
Does anyone else totally hate the little white ones? they're used for power to the cRio breakouts and the radio power out on the PD board. My electrical student has a really really hard time doing them, so usually I do all of them for her.
I don't like them, after a while you get used to working with them, but I have seen a few that have broken apart from someone putting too much force on the screwdriver. Also, they are a pain if you want to attach a wire when the connector is free.
Alan Anderson
31-01-2014, 11:56
So everyone seems to generally like the big WAGO's on the PD board.
Does anyone else totally hate the little white ones?
If you don't have the right tool, they're certainly hard to use. On the other hand, if you do have the right tool, they're easy. We used a grinding wheel to make a "shaved" Wago tool, and another small similarly shaved screwdriver, that fit them fine.
The only Wago connection that I truly wish would go away is the one on the PDB's dedicated 5 volt output. I've never found a good tool to fit it. The best thing I've found so far is a scribe with a straight tip.
Joe Ross
31-01-2014, 12:12
The 2015 control system continues to use the larger Wago connectors on the PDB. Everything else uses tool-less push-in connectors from Weidmuller (http://tinyurl.com/ko5bvxh). These are the same connectors used on the 2CAN. They require a little practice to get the wire stripped to the correct length, and the wire must fairly straight (too many insertions and removals may require starting over).
Part numbers and links please.
Glad to help!
First hit shows the interesting product line from Linear (http://lmgtfy.com/?q=linear+technology+electronic+fuse)
First hit shows the interesting product line from Infineon (http://lmgtfy.com/?q=infineon+power+mosfet)
More specifically, the LTC4364 (http://cds.linear.com/docs/en/datasheet/436412f.pdf) and IPT004N03L (http://www.infineon.com/dgdl/IPT004N03L_rev1.2.pdf?folderId=db3a304313b8b5a6011 3cee8763b02d7&fileId=db3a30433e9d5d11013e9e0f382600c2) are attractive.
EDIT:
And for the low-current channels, TI makes a pretty great device (http://www.ti.com/lit/ds/symlink/tps24751.pdf).
martin417
03-02-2014, 08:08
This thread has wandered a good bit from the OP's question which was:
Is it legal to have more than one power distribution board?
In 2012, our vision tracking relied on a consistent light color and intensity. Whenever we shot and the motors had to work to spin up the shooter, or when we drove hard, the LEDs would dim and we lost tracking. So on Friday night, we dismantled an extra PD (removed the blue plastic case, and most of the WAGO connectors), then connected it as a load to the other PD, then used the boosted 12V power supply (normally used for the WiFi bridge) to supply the LEDs. That way, even when the voltage dropped, the LEDs remained at a constant brightness.
Since the PD was modified, and connected to a circuit breaker, it was considered a custom circuit, and therefore legal. (yes, we did get re-inspected).
vBulletin® v3.6.4, Copyright ©2000-2017, Jelsoft Enterprises Ltd.