The trains are the Stadler KISS model, from Switzerland.[1] Many in use worldwide since 2012. Caltrain is using the 25KV version, which is high for a commuter line but compatible with the California high speed rail system. (BART is 1KV. Streetcars are 400-600V.)
Some of the Caltrain electric trainsets are currently running, intermixed with the two generations of Diesel trains. And the occasional freight train, which is a Union Pacific operation.
I did see one electric trainset being towed by the breakdown locomotive, an old Diesel that Caltrain uses to recover stuck trains.
25kV is the standard for all new mainline railroads these days. Modern electrical technology means there's no reason not to use high voltage AC unless there are issues with clearance(streetcars).
It's worth noting that BART's mainline 1000 volt setup is pretty unusual (and thus expensive). BART's idiotic cable car is, well, a cable car. And eBART is diesel (DMU).
Some of the Caltrain electric trainsets are currently running, intermixed with the two generations of Diesel trains. And the occasional freight train, which is a Union Pacific operation.
I did see one electric trainset being towed by the breakdown locomotive, an old Diesel that Caltrain uses to recover stuck trains.
[1] https://en.wikipedia.org/wiki/Stadler_KISS