VRM Weak Power Input Connection

Technical Electrical
#1

Hi CD!

As long as I have been with my team, I have always lacked faith in the PDP ports for the VRM (20 AMP fused channel I think). They seem to grasp the wire quite insecurely and I am afraid that if it is weakened over time, the result could be quite troublesome.

So, I am reaching out to see if anyone has found any sort of connector or technique that holds well.

We cannot find a solution that actually fits this port; we have tried ferrule connectors, and they will not fit into the port as far as I am aware. It seems that they fit into the CAN bus terminals but not these ports, so I am also interested if someone managed to fit them in here.

Thanks!

#2

I standardized the usage of wire Ferrules on the end of all of our wires going into all of the PDP and VRM slots. They fit right in the slot and grasp well. We have not had a failure since implementing them. I believe CTR Electronics does sell some themselves inducing the crimp tool. We have the tool but I lean to buy the ferrules from automaton direct, It’s cheaper. There are also some cheaper kits that can get you started on Amazon.

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#3

We’ve gotten ferrule kits from inventables for the last couple years using our voucher.

#4

We have always used ferrules for the small connections on the PDP, and this year we began using them for the big WAGO ports as well. I have found that it is important to use the proper size ferrules. Using a size too large won’t make the proper crimp shape, which can cause them to not fit into the ports. For instance, the CAN bus, we use probably 20AWG ferrules, and for the VRM/PCM, we use 18AWG ferrules, 12AWG ferrules for big ports.
As far as where to buy, I have found that sourcing ferrules from AutomationDirect is very cost effective.

#5

Thank you all! I assume that I was assuming incorrect wire sizes. Thanks once again!

#6

I was thinking earlier that I had never seen a problem that wasn’t obvious on the quickest inspection, but I have always pushed using a size or two larger wire than the rules require, especially at the smallest end because a tiny bit of damage to a 22AWG wire from an amateur stripping a wire a bit off angle can be significant. I think we always used at least 20AWG, and usually 18AWG for the VRM and PDP ports. I know I never bought bulk wire (no connectors) smaller than 18AWG.

#7

All of the Weidmuller connectors are from the same product family across the PDP, VRM and PCM. How do the connectors on the VRM port look? On my son’s team, someone pushed too hard on one of the Weidmuller connectors and damaged it so the little white button never comes back up.

The user manuals published by CTRE specify a strip length of 3/8". After some experimentation, I found that one should not deviate from that strip length by more than 1mm. If the strip length was too short, the clamp would not grip the conductor properly and it was easy to pull it out. Too long and it left exposed conductors above the connector making it easy to short between adjacent wires (often the opposite polarity).

The user manuals also specify a wire range of 24 to 16 AWG. I have always found it difficult to get the 16 AWG wire to go in without a few strands not going the hole and sticking out sideways towards the adjacent wires.

#8

Fun fact, hot glue is a great tool for keeping wires in place.

#9

Make sure not to get it into the connectors.

1 Like
#10

Unfortunately, Inventables hasn’t carried their electrical stuff for a while. AndyMark does have them in though, if you have some voucher money left you could use it there.