I recently put together a document that describes our Issuer implementation of Transaction Velocity Checks during the authorization process. We use a facility called the Velocity Manager to implement authorization rules that are based on frequency of transactions over a given time period. Velocity profiles can be used to implement extensible velocity-based logic.
Here is the data-structure that defines our Velocity Limits:
Here is a snapshot of a configured Velocity Limit based on Accumulated Transaction Amounts:
Here is a snapshot of a configured Velocity Limit based on Transaction Counts over a given period: