- Type "B" Characteristics
Developed primarily to protect conductors and low-level signal devices such as PLCs. Instantaneous trip is three to five times the rated current of the Supplementary Protector (3~5 × In). The fast trip time of these devices minimizes damage to control circuit conductors from low-level faults.
- Type "C" Characteristics
Developed primarily for applications with moderate inrush currents such as lighting, control circuits and appliances. Instantaneous trip is five to ten times the rated current of the Supplementary Protector (5~10 × In). The higher instantaneous trip level prevents nuisance tripping, and components being protected can typically withstand higher fault currents without being damaged. - Type "D" Characteristics
Developed primarily for applications with high inrush currents, i.e., transformers, and motors. Instantaneous trip is ten to twenty times the rated current of the Supplementary Protector (10-20 × In). The high instantaneous trip level prevents nuisance tripping, and components being protected can typically withstand higher fault currents without being damaged.