An electrical device like this requires a reverse leakage current of 1μA @ 91V.While the device is operating, the maximum voltage - Zener (Nom) is reduced to 120V.For operation, diode reaches 1.2V @ 500mA at the maximum voltage - Forward (Vf).
BZG03C120-HM3-18 Features
reverse leakage current of 1μA @ 91V 1μA @ 91V is the maximum voltage (Tol)
BZG03C120-HM3-18 Applications
There are a lot of Vishay Semiconductor Diodes Division BZG03C120-HM3-18 applications of zener single diodes.