@Warthog_Driver Personally I really like the postwar ZWs. I have two on my layout. But if using any postwar transformer to power modern engines with electronics, external Airpax Instant Breakers are IMO ideal along with Transient Voltage Suppression Diodes (TVS). The above link to another OGR thread, provides more information about how to select, order, and install them.
In the event of a derailment, the combination of these two types of devices instantly removes power from the tracks and clamps down on the high voltage spikes that are generated by the currents of collapsing electromagnetic fields in the motor and transformer coils and the repeated bouncing of the train wheels on and off the track, especially at turnouts .
By their nature, coils resist changes in current flow. So when the voltage source is abruptly removed and redirected, the coils keep pushing the current flow until the energy is dissipated, generating high voltage spikes in the process. When that high voltage energy makes it to the sensitive electronic circuitry in a modern locomotive, it can be quickly toasted.
These instant breakers stop the current flow in less than 100miliseconds (much faster than fast acting fuses) and the TVS diodes short circuit (clamp) the high voltage spikes. This is how they help protect modern electronics.
