Power source switchover
When the voltage falls below 0.85 times the nominal voltage for longer than 0.5 seconds, the system must switch over from the normal power supply to the emergency power supply.
When the voltage exceeds 0.85 times the nominal voltage for at least one minute, the system may and should switch back to the normal power supply.
The E3YF400VE20 0.85 has a fixed threshold of 0.85 the nominal voltage. If the mains voltage falls below this level, the monitoring relay sends the signal to switch to the emergency power supply.
The integrated time delay of one minute prevents the system from switching back and forth when the power supply fluctuates excessively over a longer period. One minute after the mains voltage returns to the normal level, the monitoring relay sends the signal to the system to switch back to mains voltage.
– Both functions (monitoring and time delay) are combined in a single unit, which saves space
– Time savings during wiring, as only one device needs to be connected