PN-2 400 and are intended for protection at overloads and short circuits of power and auxiliary chains. electroinstallations of the industrial enterprises, public and residential buildings of three-phase alternating current of 380 V - 220 V with a frequency of 50-60 Hz.
The safety lock of PN-2 consists of a fusible insert of the contact bases and the insulating case.
The fusible insert consists of the insulator (cover), a fusible element filled with quartz sand. At increase in current above nominal, the fusible insert fuses. At burn-out of a fusible insert, quartz sand completely suppresses an arch, and also possible ignition.
For installation of a safety lock, it is necessary to get the holder of a safety lock on an insulating basis, it is possible on ceramics or other isolating material.
PN-2 safety locks on technical characteristics happen the different power and also a standard size, respectively and the holder has to correspond to the power and the size of a safety lock.
As a rule safety locks are mounted together with the disconnector a knife switch , in a box or in an electric case with different degree of protection of IP-20, IP-40, IP-54, IP-65, from external factors, moisture, steam, hostile environment, etc.