Silver Conductive Grease Your experiences?

3t3d · Feb 27, 2019

Looking at a bolted bus bar connection, with some serious amperage and minimum surface area.
Material is silver plated 110 copper.
About 1200 amps per square inch of contact surface.

Any experience using a silver grease, to enhance conduction, and reduce resistance?
Any other products come to mind?

Thanks again.

sfriedberg · Feb 27, 2019

That application is well beyond anything I've dealt with. I've used a conductive grease when making up raceway bonding connections, but that's not even in the ballpark.

Do you know the worst-case operating temperature of the junction? That could be extremely relevant for the type of grease you select.

crossthread · Feb 28, 2019

I personally don't think there is any substitute for a well designed buss bar with enough contact surface area to handle the load. I don't think you could do much better then using a silver plated copper buss. I know when I was doing maintenance in the wind tunnel at Wright Patterson, we had a regular schedule for tightening the buss bar bolts. I never saw or heard of any coating to put between the buss junction but there may be something out there now.

Pathogen · Feb 28, 2019

If you expect to overload the buss bar in the present environment it occupies, reduce the temperature of the buss bar material.

gbent · Feb 28, 2019

Make sure those connections are on your regular basis list of areas to check with the infrared camera. And don't fall into the trap of checking when the shop is empty because there is nobody to bother you.

BobRenz · Feb 28, 2019

Back when I worked on railroad passenger cars, the cars were equipped with all 32 volt DC lighting & power systems. These were fed by axle-driven generators with a large battery bank. We had a silver plating setup in the shop that we used to plate all the 1/4" x 2" bus bars and knife switch contact areas on each car's switchgear. The bus bar joints ran cooler when we plated them.

Sorry, but I don't have any numbers - this was 40+ years ago

9100 · Feb 28, 2019

We shipped thousands of locomotive braking and reversing switch contacts that had the connections tin plated, never had a complaint. I never could get a clear statement of the currents but each contact carried 500 horsepower. The power was generated as three phase AC and full wave bridge rectified and the entire load was carried on one set of buss bars, also tin plated. The connection area was not more than 3 square inches. We never got one back that showed arcing at these connections.

Bill

Doozer · Feb 28, 2019

I used to work in the power transmission industry.
We made switches up to 5000 amps and I forget how
many KW. We would do heat tests with 5000 amps at
2 volts. Usually copper anti-seize was used on the
terminal pads. We used to use silver anti-seize,
but found the copper based stuff was 90% as good
and cost much less. That is what we shipped all
our switches with. The contacts were however plated
with silver.

--Doozer

MattiJ · Feb 28, 2019

3t3d said:
Looking at a bolted bus bar connection, with some serious amperage and minimum surface area.
Material is silver plated 110 copper.
About 1200 amps per square inch of contact surface.

Any experience using a silver grease, to enhance conduction, and reduce resistance?
Any other products come to mind?

Thanks again.

That is quite a lot, considering that ”normal” rating for the bus bar itself is about 1kA/sqin!
What is the current density in the busbars itself? Makes difference if you run the busbars already extra hot and toasty and want to add some contact resistance losses on top of that.

deltap · Mar 1, 2019

Bus bars I have worked were bolted together using spring (belvue?) washers to keep connections tight over time.

MattiJ · Mar 1, 2019

deltap said:
Bus bars I have worked were bolted together using spring (belvue?) washers to keep connections tight over time.

Same around here. Belleville washers are pretty much standard on bus bar bolting. 50 000 amp bus bars have more than a few bolts to tighten.

DDoug · Mar 1, 2019

Penn Union in Edinboro, Pa.

OR

Electric Materials, North East, pa.

Call them.

Jim Moser · Mar 1, 2019

I just bought a small tube of silver conductive grease MG chemicals #8463 for a different purpose as we use a copper braided battery ground cable to bond the boat propeller shaft , Thought it might help to keep corrosion and wear down, haven't tried it yet but I did put an ohm meter across a dab of it and it doesn't seem to be as conductive as I would think. Seems similar to No-lox used for electrical wiring with dissimilar metals. I like the idea of copper never seize, should of tried that, a lot cheaper. I see more than 1 K ohm across a dab of this stuff so doesn't seem that conductive to me but maybe it is in a thinner film thickness?
8463 - Silver Conductive Grease - Conductive Greases | MG Chemicals

TDegenhart · Mar 2, 2019

Be sure you have electrical grease, not heat transfer grease. Electrical grease is normally used on draw out circuit breaker stubs. Clean joints, silver plated or bright acid tin plated. The handbook says to use petrolatum or other special compounds to exclude air. No particular clamping pressures are given, but the tighter the better. One item to be careful of is thermal expansion. 1000 amp per sq inch is standard max current density for open buss bar. The actual density is determined by a heating test, max average temp of 30C over 40C ambient. Max spot temp is 35C.

Tom

Forestgnome · Mar 3, 2019

I've never heard of using any kind of grease to increase conduction in electrical connections, only as an anti-seize, or to prevent corrosion. Silver conductive grease is normally for heat conduction, not electrical conduction.

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Silver Conductive Grease Your experiences?

3t3d

Diamond

sfriedberg

Diamond

crossthread

Titanium

Pathogen

Hot Rolled

gbent

Diamond

BobRenz

Stainless

9100

Diamond

Doozer

Titanium

MattiJ

Titanium

deltap

Cast Iron

MattiJ

Titanium

DDoug

Diamond

Jim Moser

Hot Rolled

TDegenhart

Diamond

Forestgnome

Stainless

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