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August 1999

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Subject:
From:
"Thorup, John" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 30 Aug 1999 14:31:40 -0700
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sounds a little flimsy for 50 amps but if it worked for 5 years...  I
would guess oxides have formed on the contact surfaces.  clean them up
with a very fine sandpaper, solvent wash and reassemble with an oxide
inhibiting compound.  this is the goop electricians use when terminating
aluminum wires in load centers with Al/Cu compatible terminals.  you can
get it from your electrician or Home Depot type of store.  possibly the
attachment of the wires to the terminals (crimp?) is loose? good luck
John Thorup

> -----Original Message-----
> From: Sean Hager [SMTP:[log in to unmask]]
> Sent: Monday, August 30, 1999 2:24 PM
> To:   [log in to unmask]
> Subject:      [TN] Electro-mechanical connections for Power
> Applications
>
> Hi Group!
>
> I am currently having troubles with a terminal connections to the +5V
> output of a switching PS.  The current configuration basically
> consists of
> 0.5"x0.7"x0.060" aluminium bus bar (with hole for hardware), connected
> to 2
> 8guage stranded cables, via 2 8guage red ring lugs (tin/lead plated
> copper).  These are connected using 8-32 Screw and Hex nut w/ lock
> washer.
> This is my list of questions:
>
> Is the standard torque for this hardware type adequate for 50+ amp
> capacity?
>
> Do the ring lugs or bus bars require any preparation (cleaning,
> scoring,
> etc.) prior to assembly?
>
> Are there any special concerns with the dissimilar metals?
>
> How would you (or what standard would you use) to join this harness
> and
> terminal?
>
> I have seen a full 200mv across the bus bar/ring lug junction at
> [log in to unmask]
> There is no visible corrosion on either termination, and the hardware
> torque was approx. 15-20 kg-cm.  Generally this connection has been
> very
> reliable for about 5 years, lately we have seen a notable rate of low
> output on 5V attributed to "contact resistance" while loaded.  The
> manufacturer (Power Supply) has no hardware or installation
> guidelines.  I
> could best describe this as the "loose battery terminal effect" as
> compared
> to an automobile.  Is the solution realy as simple as clean and
> tighten?
>
> Thanks,
> Sean
>
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