A9D33620 = SI (Super Immunised)
A9D32620 = Type A (AC or pulsating DC)
RCBO = Tripping is ensured for residual sinusoidal alternating currents and residual pulsating direct currents, whether suddenly applied or slowly rising.
RCBO = With all the features of a Type A device, “Si” type Super Immunised earth leakage protection range has been specially developed to be used with loads or in environments causing disturbances. Examples are lightning or switching surges, harmonics generated by increasing number of loads and constant load leakage current from electronic ballasts, speed drives, computers, etc. The Si increases safety and allows improved continuity of supply.