Protection relays are often the last barrier to protect rolling stock and trackside equipment in the event of upstream protection system failure. They do not require auxiliary supply. Their mechanical life of 100 million operations exceed train life.

Protection relays are designed on an electromechanical technology providing high reliability with friction free mobile armature and maintenance free. It has a strong ability to withstand high overloads due to its magnetic materials. It is equipped as standard with weld-no-transfer contacts (1N/O+1N/C) for safety critical applications.