4
TB MRI3-ITE(R) 12.00 E
1
Introduction and Application
The digitial multifunctional relay
MRI3-ITE(R)
has been
designed as a universal time overcurrent protection re-
lay with thermal replica for generators, transformers
and cables.
The relay gives a complete thermal characteristic of the
electrical equipment to be protected taking into ac-
count its initial load.
The
MRI3-ITE(R)
furthermore provides a universal time
overcurrent and earth fault protection with the follow-
ing functions:
•
Integrated determination of earth fault direction for
application to power system networks with isolated
or arc suppressing coil (Peterson coil) neutral
earthing (ER-relay type),
•
independent (Definite) time overcurrent relay.
•
inverse time overcurrent relay with selectable charac-
teristics,
•
two-element (low and high set) earth fault protection
with definite or inverse time characteristics.
Important:
For additional common data of all
MR
-relays please
refer to manual „
MR
-Digital Multifunctional relays“.
2
Features and characteristics
•
Microprocessor technology with self-supervision,
•
measuring of phase current as RMS value,
•
digital filtering of the measured values by using dis-
crete Fourier analysis to suppress the high frequence
harmonics and DC components induced by faults or
system operations (earth current only),
•
in accordance with the requirements as per
IEC 255-8, VDE 435 part 3011 for overload
relays,
•
two parameter sets,
•
selectable protective functions between:
definite time overcurrent relay and
inverse time overcurrent relay,
•
selectable inverse time characteristics according to
IEC 255-4:
Normal Inverse (Type A)
Very Inverse (Type B)
Extremely Inverse (Type C)
Special characteristics,
•
Reset mode for inverse time characteristics selectable,
•
high set overcurrent element with instantaneous trip,
•
two-element (inverse time and definite time) overcur-
rent relay both for phase and earth faults,
•
determination of earth short-circuit fault direction for
systems with isolated or compensated neutral point,
•
Display of measuring values as primary quantities,
•
measuring of phase current of the short circuit
breaker operation,
•
blocking of high set element (e.g. for selective fault
detection through minor overcurrent protection units
after unsuccessful AR),
•
the protective functions can be freely assigned to the
output relays (assignment matrix),
•
withdrawable modules with automatic short circuiters
of C.T. inputs when modules are withdrawn,
•
storage of trip values and switching-off time (t
CBFP
) of
5 fault occurences (fail-safe of voltage),
•
recording of up to eight fault occurences with time
stamp,
•
switch failure protection,
•
serial data exchange via RS485 interface possible;
alternatively with SEG RS485 Pro-Open Data Proto-
col or Modbus Protocol,
•
Display of date and time.
