have you personally observed kerala running on HOG ? every time ? for example 303 series of RPM are not HOG but they do haul Kerala, HOG is no constraint for a LSA de-link and there is no rule that a train needs to be hauled by a specific type of WAP7, all i want to say is there is no guarantee that a LSA can be followed, as long as there is a wap-7 power available at a trip shed it will be sent with a train, else the next in line is a WAP-4 from either home zone to begin with, if that is also not available then the next available WAp4 is sent.