Hi Raj,
We don't have a specific  limit for excessive. Essentially, we are monitoring all activity, and if a user begins to 
request at a rapid speed to the point that they are interfering with the normal operation of the system, or with other 
users ability to access it, they would become blocked.
We don't want to have an exact specification on it, especially while it is still new, since the availability of 
resources and fluctuation of user activities can change from minute to minute.

We also ban a user quicker if they are not "known" to us- i.e. they signed up for the system as a developer and were 
working on some sort of project, but are now hitting at a rapid enough rate to be acting more in a commercial capacity. 
A user is "known" to us when they have reached out to provide their organization affiliation, detailed contact 
information and a description of what their project is/how they are using the data. The more information we have, the 
easier it is to contact you about potential issues before your account gets banned (of course, we don't guarantee this 
though).