After five consecutive failed login attempts, the administrator account is locked for 15 minutes.
For NSX Manager, NSX Controller, and NSX Edge nodes the administrator account is locked out for 15 minutes after the fifth consecutive failed login attempt. To reset the locked account, wait 15 minutes to login again. This behavior is intentional, in that it prevents an attacker from learning of the existence of an account by observing the change in login failure messages from "incorrect password" to "account locked."
This applies to administrator logins via SSH, or via the console.