You are powering a coil by depending on track activation based on conduction of the wheels from one outside rail, up the wheel across the axle and then down that wheel back to the rail while rolling down the track.
Then you get into how many times back to back and how long can you cycle the coil without melting it, at a given track voltage.
#1 STOP activating every pass of the train.
#2 control the voltage carefully to limit the current and heating- preferably a fixed accessory voltage.
#3 incorporate a relay or other track sensing setup for positive activation instead of passing direct coil current through the wheels and axles of passing cars for activation. Any number of add one items, be it a 153IR detector, one of these https://hennings-trains.shopli...al-driver-rev-2.html , or a DIY relay, or a manual switch for activation.
