Concept of protection of the main-supply(230/400V) should be considered in order to be able to absorb long duration pulses with high amplitudes from lightening discharges as well as to achieve a low residual voltage level. Hence multistage protection level is important to incorporate in the power supply system.

The surge protection device class B with 10/350µsec wave form is with MOV technology should be installed on all sub distribution panels with in a facility that supply power to critical equipment.

Class D arrester is a Pluggable device. It is a combination of the MOV & high capacity G.D tube. This is used for fine protection of the sophisticated equipments. Indication on the arrestors facilitates the user to see the health status of the arrestor.