Many years ago that was explained to me this way (I never did any further research so I have no idea if this is correct or not):
The spinning of the centrifuge creates static by it's mere operation, no way to avoid this. The static is supposed to harmlessly bleed off to ground. If it doesn't dissipate to ground it will build up until the static causes any arc which can go directly through the control board and fry it.
Like I said, I never researched this answer but it seemed logical.
