The phase failure relays are designed for applications where a three-phase system needs to be monitored for unbalance or deviation in balanced voltage. The relays includes a standard timing function. In addition the PADI and PANI 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. If an external stable power supply is available the 45mm housing offers seperate terminals for internal power.
A - function monitors the three-phase system for unbalance due to phase angle and phase voltage deviations e.g. a blown fuse or a bad connection.
B - function monitors the three-phase system for both unbalance (as the A - function) and balanced under voltage.
C - function monitors the three-phase system for both unbalance (as the A - function) and balanced over voltage.
D - function Monitors the three-phase system for all possible deviations by monitoring unbalance and balanced under-and over voltage.
Unbalance due to phase angle and phase voltage deviations is very accurately measured by measuring the inverse phase system relatively to the main system. The method is independent of the actual balanced voltage and very insensitive to electrical noise. Balanced voltage is measured by rectifying and adding the threephase voltages.
Operation:
Under normal phase conditions the relay is energized and the green LEDs are switched on. If a phase failure is detected, or the supply voltage for the electronic system is lost, the relay drops out and the LED, related to the type of failure, is switched off.
Application:
To switch off motors automatically before damage due to faulty supply, and to switch them on again as soon as the supply is re-established. E.g. pumps, oilburners, ventilators and refrigerators. To monitor the three-phase main system and control the use of local emergency generators. To prevent motors from being switched on to a faulty supply e.g.cranes and elevators.
