Shunt Resistor Heat Sink Installation

CevinMoses

Member
Join Date
Jan 2010
Location
Wisconsin
Posts
43
I have an AB Kinetix 350 that I'm setting up in a new system. I am getting a Overvoltage fault, as my DC buss is spiking to 850VDC. The book says to install a shunt resistor, 2097-R6, and to install it on a heat sink:

The shunt resistor can operate at its full power rating if it is mounted vertically on a 200x200x3mm(7.9x7.9x0.12in.) heatsink at 25C (77F) with a clearance of 12mm (0.5 in.) on the sides and 50 mm (2.0 in.) above and below.

http://literature.rockwellautomation.com/idc/groups/literature/documents/in/2097-in002_-en-p.pdf

What it does NOT say is what that heat sink should be made of. Am I supposed to just use a piece of aluminum stock cut to size drilled into the cabinet wall? Should I mount it with thermal paste? This thing says it will reach up to 392F. That's a lot of heat inside the cabinet. What's the best practice here?
 
Last edited:
Easy:

Teflon off sets, about 3/4 inch, they will be good to just about 700 degrees

Cabinet fans, one push, one pull. in proximity. bottom to top. The larger the sink the more heat it will dissipate.

Aluminum works good, copper would be better,

Not so easy, Higher maintenance.

If your really industrial, drill two holes long ways thru the block, pipe tap 1/4 inch. Plumb a turn around on one end, then plumb the other to run thru a small water tank. A sub pump like you would find on a lathe. Higher maintenance.

Good luck
 
Thanks, John. That is much more information than I've been able to get from AB. My distributor actually said he's usually seen them just mounted to the back panel of the cabinet. I appreciate a more thorough list of options and techniques.

PS- Your profile says you're in San Antonio. I grew up on the north side, just off of Blanco Rd. between the loops. Miss that city and it's great food.
 
I don't know if I saw exactly how much heat it generates. The spec says it is rated at 150W max, but it might be generating much less.

Yes, use a plain aluminum plate. It will absorb and spread the heat. Thicker and bigger is always better, if needed.
Yes, use a thin layer of thermal compound to improve the thermal flow from the shunt resistor to the plate.
Yes, bolt the shunt tightly to the plate. It will improve the thermal flow.
If you bolt the plate directly to the cabinet wall, use thermal compound here also. The plate is 64 square inches. Some heat will pass directly to the cabinet wall and the exterior. A painted cabinet or a stainless steel cabinet passes the heat more slowly, but any heat passing through is a good thing.
 

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