G-251 Mounting to Heatsink

[debetto]

When mounting 4 G-251's to a common heatsink, do I have to make sure that the aluminum plates are/remain electrically insulated (by the black anodize coating) from the heatsink? I am not sure if I can enlarge the notches on the aluminum plates and expose the bare aluminum so that the screws I have will fit.

Thanks in advance for your help!

debetto

[heymoeheylarry]

Debetto,

The mosfets are isolated on the G251.

The hard anodizing on the factory supplied heat sink provides the electrical isolation.

If you have G250 drives you need to use factory supplied anodized heat sink or some sort of isolation such as mica .

[debetto]

Thanks for the reply, but I think I wasn't too clear with my original question.

I have 4 G-251's which came with aluminum plates attached. I read in the manual that these are connected to motor ground. I am planning to mount these drives to a larger heatsink. The screws that I have are a tight fit, and I am concerned that they will strip off the hard anodized coating causing the drives to get electrically interconnected to each other and to the chassis via the aluminum plates--I think this should not be an issue but I wanted to be certain.

I am not concerned about the isolation of the mosfets because the aluminum plates came attached from the factory, and therefore would have been properly isolated.

I hope this clarifies my question.

[tumutbound]

Sounds like a question you should ask of Gecko.

(What's forcing the use of larger screws?)

[jalessi]

Debetto,

Using lock washers or star washers on the mounting hardware would also breach the anodizing, it does not matter.

How could common grounding a isolated aluminum plate to another isolated aluminum plate cause any harm?

All the heat sinks are isolated from any of the electronic components!


Jeff...

[debetto]

I was hoping soemone from Gecko would answer. I guess I could always go to the store and get smaller screws. I just can't imagine having to rely on the black anodized finish for insulation if it is that critical.

[jalessi]

Its not critical, none of the heat sinks are electrically connected to any of the components.

[debetto]

Exactly what I was thinking Jeff...I guess I was being overly cautious!

[Mariss Freimanis]

The plate is grounded in the the G251 drive. It connects to the power supply GND terminal via the two board to plate mounting screws. The G251 may be mounted on a chassis with no regard to the integrity of the plate anodizing.

Mariss