3 Phase under voltage control relay with phase sequence detection

The 3 phase 4 wire voltage relays are designed for applications
where the three phases need to be individually monitored for
under voltage against neutral and correct phase sequence. The
PNDA and PNDI contain a standard timing function. In addition
the PNDI offers a true time delay on drop out even at total power
failure. The relay works in “fail safe” mode and need no external
power supply.