Tripping characteristics [t-head1]

The overload relays ZE, ZB12, ZB32 and the Z5 up to 150 A are, due to the German Physical/Technical Bureau (PTB), suitable for protection of EEx e-motors to the ATEX-Guidelines 94/9 EG. In the relevant manual all tripping characteristics are printed for all currents.

These tripping characteristics are mean values of the scatter bands at an ambient temperature of 20 ˚C from cold. The tripping time is dependant upon the current. When units are warm, the tripping delay of the overload relay drops to about a quarter of the value shown.