Application and
Description
The type MFVU 21 digital, definite
time relay consists of two fully
independent frequency monitoring
circuits which can be used as either
under or over frequency protection.
In addition, the two operating
circuits can be used together to
provide pick-up and drop-off at
different frequencies.
The relay is suitable for any
application in industrial plants and
to generators where definite time
under or over frequency protection
is required.
In addition multi-stage schemes
using several relays can be
provided for load shedding and
reconnection applications.
Integral timers are provided for each
operating circuit and separate
eletromagnetic auxiliary relays
ensure maximum flexibility of
application.
Figures 2 and 3 are block diagrams
showing relays suitable for use with
ac and dc auxiliary power supply
voltages respectively.