There is a user who down votes 90% of the time and that is his privilege. How many time can I down vote him before I am interrupted?
A few things:
The user you refer to has cast quite a few votes, but only about 81.7% of them are downvotes, not 90%. Call this pedantry, but I think it's important to distinguish between claims and facts.
Vote on the posts, not on the person. Targeted serial voting like this is unacceptable and may result in disciplinary action.
Stack Exchange does not reveal the details of the voting algorithms to any users, even to moderators. If people did know, they could do what you're proposing, and try to beat the system.
You've posted a number of questions that have been downvoted. I wouldn't be surprised if the user you mention has indeed voted on some of those questions, and indeed downvoted some of them. This shouldn't be a surprise, because some of your questions haven't been that great; you've gotten some feedback in this regard and I hope it will lead to better questions in the future.
All that said, you should not - I repeat, not - make assumptions about the actions of others. There's no way to see who voted which way on what post, and even if there was, you shouldn't assume that the voting was unjustified. The user in question does downvote a lot of posts; he or she simply has different standards than the next person. Who are any of us to say that this user is incorrect in the way they vote?
To be very frank: you shouldn't even be contemplating this questions; you should always vote the quality of the content and never the user who posted it.
Nor will anyone tell you what the limits of the automated vote-misuse detection system are. That would rather defeat their purpose.