non de-railing question

If your train enters a switch and the switch is turned the wrong way, with the correct wiring the switch will automatically move to the correct position.  non-derail. 

Here is a link to DZ 1000 switch motor installation instruction that shows non-derail wiring.   Click on the underlined phrase, Diagram is at the bottom of second page. Note the small isolated rail inputs at the frog of the switch.  When the lead engine or car axle crosses this point, completing the circuit, the switch motor is activated similar to the push button.  Do all wiring exactly as diagrammed.

Some killed power to the track not aligned with the sliding points also.

The wiring method already explained above is the better way to do non-derail, but some switches are made to be non-derail. The switch points are spring loaded. Engines and rolling stock with enough weight will move the switch points out of the way and allow a train to travel through the switch when it is in the wrong position. However, this method does not always work properly (usually with lighter rolling stock) and can sometimes cause a derailment. It is not the best thing to rely on for the prevention of derailments.