What is a crowbar and what is it used to protect?
A crowbar protector is a voltage dependent device which will crowbar the DC bus. Crowbar means to short out like a switch turning on and staying there. A crowbar device differs from other types of surge protection devices, like a varistor, in that it will not return to an open circuit unless power is removed. Crowbar devices are often used to protect a load from damage due to a runaway power supply. When power supply regulation fails, a critical load can be damaged if its maximum supply voltage rating is exceeded. A crowbar device prevents the damaging voltage from damaging the load by shorting out the supply at a predetermined voltage level.
