We have now reached a time with transmission switches where the major vulnerabilities for failure are the battery and charger used to power the switches, rather than the switch itself. In fact, a majority of switch failures are a result of a dead battery. Even though utilities are employing the smartest, “smart-chargers” and the best quality batteries, the life and the reliability of batteries are not improving.
Batteries and chargers sitting for months or even years without use become sluggish and then useless in only a few years. Utilities employ the most expensive way to monitor batteries, sending people to a switch site for maintenance to check batteries. Even that has proven not to be dependable, as a battery may operate normally one day and yet be dead just days later with no one being the wiser.
Then, during a storm when the power is gone, the batteries are called upon to be used, only to learn at the time of need the batteries no longer work. Without effective monitoring, then batteries which may have been dead for days or even weeks go unnoticed because the low-voltage relaying typically used is just looking at the smart-charger and not the batteries. Even if the batteries have voltage, there's still a possibility that they will not handle a load.