Protective relay

摘要

A protective relay is provided to protect circuitry against reverse battery polarity or load dump, wherein a relay coil is operatively connected to a contact switch and is fed by a reverse bias diode (which may be a Zener diode) such that the relay coil opens the switch contact when the diode is energized to protect the circuitry; wherein the protective relay optionally includes a positive temperature coefficient resistor or a current source to protect the relay coil from overheating.