Terminal for flexible power cable 3

[tem1234]

Hello,

We want to use flexible power cable (locomotive cable) which have approximately 550 stranded for a 4/0.

We have 2 choices for the quick connect connector (posi-lok from cooper), crimp or double set screw.

Do you have any experience wich one is better for a flexible cable, to crimp or the double set screw?

Thank you!

 

[rcw retired EE]

Crimp.
The fine wires of the locomotive cable slide away from the set screws creating a high resistance joint. If this needs to be UL listed, make sure you get a UL listed crimp terminal. If I remember correctly, the listed terminals have a flared opening to guide the fine strands into the barrrel.

We had failures of the extra flexible cables using bolted compression terminals & set screws. This was onlarge cables 500 kcmil equivalent and larger.

 

[tem1234]

Thank you RCWILSON,

Do you know if the crimp is ok for a flexible cable or just for a standard cable?

The plug is UL498 listed.

See page of the catalog

 

[rcw retired EE]

Can't tell if that lug is rated for the fine wire in flexible cable. I would guess it is, since flexible wire is a typical application for plugs. All our termiantions were to standard 2 or 4 hole lugs, no plug assemblies.

 

[ghostbuster7]

Check with the geny rental groups.They are always supplying cam lock fittings with their stranded cable.

 

[tem1234]

The geny rental group proposed the double set screw. That's why i asked the question, because i thought that a crimp will be a lot better on flexible cable.

 

[ScottyUK]

The rental group is probably thinking of what is field-repairable by the average engine fitter. I'd go with the crimp for a reliable joint, but obviously it is a non-repairable connection.

 

[1capybara]

dont use the double set screw, its not rated for fine stranded cable, and will fail since its not designed for this application, the set screws will break the fine strands, loosen, and create a high resistance connection. I speak from experience here, using DLO cable.

 

[waross]

If this is new cable you may be able to solder the connections. If it's older and weathered it may not be possible to clean the strands enough for solder. And I'm speaking in the past. I am not sure how well the new lead free solders will perform.
I had a lot of 353 MCM Locomotive cable connections in the switchgear of the 2.2 MW plant. I had to use what was already in service and what was available in the third world.
I used double set screw connecters when I could get them, but we had single set screw connectors in service also.
If your cables are subject to movement I would expect that the strands will start breaking but our cables were a substitute for bus bars and not subject to movement. We never had a failure.
A couple of tips: Use plenty of Penetrox. Apply it to the strands, to the face of the set screws and to the threads of the set screws.
Tighten the set screws and then twist the connector back and forth on the cable. You will generally find that the strands will settle and it will be possible to tighten the set screws further. Repeat several times until the set screws can no longer be tightened any further.
The 353 MCM cable was a very tight fit in 500 MCM connectors. At times we had to gather the strands with a small hose clamp (Aero-clamp) o as to be able to enter them into the connector.
And by the way: After many years in the field, I have come to view manufacturers recommended tightening specs as an attempt to sell replacement parts. Disregard published specs and get those set screws as tight as possible. Using the manufacturers tightening specs on locomotive cable is almost a guarantee of failure.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[catserveng]

Did you look at the installation instructions for the double set screw type connector? It should have referenced you to part number 100400-5 or -8 (depending on wire size) and how to install. These are strips of copper tape you wrap around the fine strand wire before you install in the connector.

Have used both Cooper and Leviton camlocks for years in gen rental business with set screws and fine strand weld type cable. When properly installed no problems. Have also used crimp style and they work fine, cost of setting up multiple technicians got pricey though.

Thousands of cables in service in over 30 years experience. Do it right, use right parts and procedures, they work as designed for use with proper type flexible cables, what they are made for.

In your catalog look on page 73 under accessories and tools, you'll see pictures of the straps. As I remember most single packed connectors cam with them.

Hope that helps, Mike L.

 

[thinker]

Square D recommended to wrap finely stranded wires with thick copper foil, then you can use set screws (one or two). We use this recommendation for heavy duty systems, no failures have been reported for years.

 

[panelman]

Have you thought about using bootlaces?

 

[mls1]

As already stated, high strand wire can be easily damaged with non-listed crimps or direct set screw installation. There are sleeves for installed high strand under set screws. We've recently installed quite a bit of high strand and we've been using crimp on pins (up to 500MCM). The pin is then suitable for installation in the set screw. The one key point is the lug or compression pin must be listed for use with high strand wire and they must be installed using the tools recommended by the manufacturer.