"DIN rail" or Not

[techtiger1]

The din rail was not my favorite thing in the beginning either. However we learned a few useful things about it. Tinning the wires is a must and you need a fairly good soldering iron to do this given the required gage wire. This is important because of the Allen cap screw contact method it makes it so if you don't eventually you'll tighten the screw so much it will move all the wires to the side causing bad contact. Finally you can cut the rail it self to use what ever you want and it really isn't that much weight.

Just a few things,
Drew

[BlackShadowFox]

i Agree with what you are saying but for my design i need to use this method i came up with in order for it to fit.

[Doug G]

Originally Posted by techtiger1

The din rail was not my favorite thing in the beginning either. However we learned a few useful things about it. Tinning the wires is a must and you need a fairly good soldering iron to do this given the required gage wire. This is important because of the Allen cap screw contact method it makes it so if you don't eventually you'll tighten the screw so much it will move all the wires to the side causing bad contact. Finally you can cut the rail it self to use what ever you want and it really isn't that much weight.

Just a few things,
Drew

I agree that the DIN rail, when cut down to size, is not much weight - heck you can probably save more weight using smaller nuts and bolts in many of these robots. Also the many complaints I've heard about wires coming out of the blocks is usually due to not providing adequate strain relief and proper securing of the wires around the block.

[MrForbes]

My only experience with wire coming out of the block, was caused by the screw not being tightened all the way. After the screws were all tightened, we never had any problems with them.

[IndySam]

I love the fact that we switched over to the DIN rail last year. It's real world stuff that you will become very familiar with when you start your career's.

[Pavan Dave]

Don't shoot me for saying this but I didn't mind the PDB after a while. Especially after we found a solution to making the wires stay.

The solution can be found in this post in this thread.

[Al Skierkiewicz]

OK,
Time to clear up a few misconceptions and fix some other notions.
1. I believe that the DIN rail is a required part of the Power Block. Although I have seen aluminum DIN rails, they are not easy to find. The steel rail when cut down to size (you do not need to use all of the blocks) is fairly light in the big scheme of things. The DIN rail is the designed mounting for this system and allows all the components to be firmly mounted and held together.

2. The wires pull out of the block for two reasons. One is the screws are not tight and two the wire is not stripped to specification of 5/8". Any shorter and the wire doesn not fill the entire depth of the clamp and the result is the wire will be forced out like a banana from a peel. As you tighten the clamp and wire is forced further out, the screw will seem loose and you will tighten it causing more more wire to be pushed out. The use of wiring retention devices and strain relief will only delay the failure of an improper strip, it will not prevent it.

3. Tinning the wire prevents the wire from being squeezed out of the clamp but prevents full contact between the clamp and the wire. This raises the series resistance and causes spot heating.

4. Although the IFI distro panel is a far better alternative in this application, I do not think it will return in the future. As a second best choice, last year's distro block fills the need for both veteran and rookie alike. I expect it to return in the 2008 KOP.

5. Although the power drawing was a little misleading, good practice recommends (read that as "requires") separate return wiring for each fuse block in use. What ever current passes through the red wires also pass through the black wires. Don't fall into the belief that no current flows in the common wiring. #6 or larger on both red and black wires, please. Daisy chaining of the fuse block power wiring causes all current from the block at the end of the chain to flow through the next block in line.

[scott]

If you do not like the DIN mounted AB Terminals, sorry but if you are going to be continuing on into Industrial Controls after Robotics they will not be going anyplace. I build Industrial Control panels for Frakes Engineering and these are standard, though we do not use anything this large.

Also on Team 447, we have been using terminal block strips for a couple years. They make it very nice when trouble shooting and when replacing components.

Check for what the torque setting should be for the terminals, we have never had a problem with them coming loose when torqued properly.

[Chris_Elston]

Originally Posted by Al Skierkiewicz

OK,
1. Although I have seen aluminum DIN rails, they are not easy to find. The steel rail

Just to expand on Al's points. If you want Aluminum DIN rail this is the part number you can order from an Allen Bradley distrubtor. Such as Kendall Electric, Wabash Electric, etc.

Aluminum:
1492-DR5

Steel:
199-DR1

http://www.ab.com/en/epub/catalogs/1...4170/tab2.html


Also I would like to touch on one thing about these power blocks. Although most would agree that they aren't the best thing to use for robot/car type methodology in wiring applications, they ARE however given to all the teams by a "sponsor" Rockwell Automation, that wants you, a student and possible future engineer, to have some experience using their products. It's no different than receiving AutoDesk products. Allen Bradley is exposing you to products you'll use in Industrial Controls, A.K.A. Controls Engineering should you choose that path. The same goes for National Instruments, ironically a competitor to Rockwell Automation for industrial controls platforms. PLC verses PC based controls....anyway....sometimes you gotta step back and look at the big picture of why things change, they change because sponsors want to see this program grow, and they also want in return to see their products or services getting some exposure. It's not because someone is punishing us. But rather let's show appreciation for what we receive and thank the big fish sponsors for their donations.

Did you know that FIRST had a booth in Chicago at Rockwell's "Automation Fair 2007"? That was the first time I had heard of it. That's big exposure for FIRST at Automation Fair.

I think back when the Apollo missions had all these problems. The engineers dumped out a box of parts on the table and said "Ok this is what they have on the rocket to work with, let's figure out how to make an air filter using these parts". Thinking of using the power blocks in this way, it's what you have to work with, make the best of it, and thank Rockwell Automation for their donations.

disclaimer:
Do I use Allen Bradley/Rockwell Automation products now? Yes, I buy thousands of dollars each week... I consider myself an expert with Alllen Bradley PLCs (programmable logic controllers), a bit biased in the least, but I do appreciate what they have done for FIRST.

[AdamHeard]

Originally Posted by Pavan

Don't shoot me for saying this but I didn't mind the PDB after a while. Especially after we found a solution to making the wires stay.

The solution can be found in this post in this thread.

Wow.... you certainly came up with a creative solution to the problem.

I'm sorry if my original post was a little rude, but we still had problems with wires randomly coming loose. Maybe there was something else we were doing wrong, but I certainly like the crimped ring terminal connection a lot better.

I understand they use them in industry, but do they really use them in places that see large amounts of vibration and possible impact?

[Al Skierkiewicz]

Adam,
The first time I encountered this type of block was in the power distro of our analog transmitter. This transmitter was built in Missasauga, outside of Toronto. All tranmsmitter module power is 50 volts so the distro is very complex. There are 8 2kW (conservative) modules in each of two cabinets for each of two transmitters. Total power is 800 Amps for a fully black picture.
In our digital transmitter we have dual redundant power distro in large cabinets on one wall of the transmitter facility. Three phase power comes in through these blocks, then distributes to the rest of the cabinet where everything electrical is mounted on DIN rails. To protect the final amplifier, the mains breakers are motor driven trip so that mains voltage will be removed within two cycles of the power line sine wave upon fault. The mains voltage then routes to time delay relays which first insert huge resistors to limit "inrush current" and then following a sufficient time delay, bypass the resistors for full power. There is obviously a variety of telemetry devices installed in the cabinet as well. Everything is installed on DIN rails including small relays like those used for the orange light. Inside the transmitter cabinets, the same rail mounted terminal strips are used for all three phase and low voltage wiring. (low being anything less than 300 volts.) This includes all blower power, DC power supplies, control wiring and telemetery. All high voltage wiring requires special handling and special hardware to prevent arcing and corona discharge. It also requires some very special safety controls so that high voltage cannot be applied with the covers open or circuitry bypassed. High voltage in this transmitter is 35,000 volts at 2 amps.

[Gdeaver]

Yes, Din rails are an industry standard and there is an amazing amount of stuff you can put on them. However, I don't believe the power distribution blocks and last years fusing solution is ideal. Now if those power distribution blocks were circuit breakers, I would be a little happier with them. Our problem is that our robots electrical system is based on 12 volts dc and industrial controls use higher ac voltages. The car automotive industry is where we need to look for solutions. Enough, I have to get to work. My first job today is to replace several components in a pump control box. They are all DIN rail mounted components. Latter today, I have to add some controls on a steam boiler control panel. They are all DIN rail components. DIN rails are every where.

[MrForbes]

Yup, DIN rail stuff is everywhere...on stationary equipment. You won't find it in cars, though. And cars are more like robots, they move around. There is no standardization on cars, each manufacturer makes the power distribution system specifically for each model, using specialized components.

[Richard Wallace]

Originally Posted by squirrel

... cars are more like robots, they move around. There is no standardization on cars, each manufacturer makes the power distribution system specifically for each model, using specialized components.

While there are few industry wide standards for car parts, it's still misleading to say "there is no standardization on cars."

Car parts are the subject of very extensive documentation and testing. Just ask any of the automotive engineers that haunt these boards.

And the quantities in which car parts are produced drives down their cost. It also drives down their failure rates, because car parts are much more expensive to replace in the field than to install initially, and car manufacturers are responsible for those costs through the warranties they must offer to stay competitive.

I agree with Gdeaver -- FIRST should be looking at car parts instead of industrial automation components.

[MrForbes]

Yes, you're right, there is some standardization in car electrical systems, as far as components such as fuses and relays and bulbs. Also the computer systems are using a few standard data bus designs. Still, the power distribution parts such as wiring and fuse boxes and whatnot are designed specifically for each model. Have you priced a battery cable for a late model car lately?

The old IFI distribution panel is probably as good as it gets...there just doesn't seem to be anything in industry that can be readily adopted to FIRST robotics use.