Littelfuse SE-330HV-21-01 is a conformally coated device suitable for resistance grounded AC systems. With multiple relay contacts configurations and fail-safe/non fail-safe operation, it offers IEEE device numbers and a range of reset options. It features standard harmonic filtering, GF trip times from 0.1 to 10.0 seconds, and supply voltage options. With RF trip level options and communication interfaces, it provides flexibility and reliability. New revision available now.