4
TB MRI(K)3-C 03.02 E
1
Introduction and Application
The digital net protection relay
MRI(K)3-C
an universal
time - over -current and earth fault relay with integrated
control- and supervision function as well as optional an
integrated auto reclosing function The earth fault pro-
tection is applicable for insulated and compensated
grids. The controlling of the circuit breaker take place
by the means of the front plate via push button in the
case of a local operation, the remote operation can
be done via digital inputs or via the serial communica-
tion interface.
The earth-fault supervision is either realised in Holm-
green connection or by means of a core-type current
transformer.
The
MRI(K)3-C
is available with rated currents of 1 A
or 5 A.
2
Characteristics and Features
•
Microprocessor technology with self-supvervision,
•
Measuring of phase currents as RMS value,
•
Digital filtering of the earth current with discrete Fou-
rier analysis, by which the influence of interference
signals, such as harmonics and transient DC com-
ponents during an earth-fault are suppressed.
•
Two sets of parameters,
•
Operation cycle counter,
•
Switch off power Measuring of the switch off power
of the CB power,
•
Suppression of an LED indication after activation
(LED flash),
•
Selectable protective functions : Definite time over-
current protection (DMT) and inverse time overcurrent
protection (IMT),
•
Selectable IMT trip characteristics of IEC 255-4:
Normal inverse (Type A)
Very inverse (Type B)
Extremely inverse (Type C)
Special-purpose characteristics
•
Reset mode for DMT/IMT trip characteristics is se-
lectable,
•
Definite element for short-circuit high-speed trip
•
Defined time overcurrent protection without direc-
tional feature (DEFT)
•
Inverse time overcurrent protection without directional
feature (INV)
•
Two element defined- or inverse time earth fault pro-
tection,
•
Optionally with integrated directional feature for the
earth fault element.
•
Control of the CB via potential free auxiliary relays,
•
Supervision of the CB via digital wide range inputs,
•
Remote indication of the CB position via serial inter-
face.,
•
CB failure protection,
•
Display of the measuring values as primary quanti-
ties,
•
Measuring of the phase currents during short-circuit
free operation,
•
Blocking of the individual protective elements or the
trip elements can be set freely,
•
The protective functions can be freely allocated to
the output relays. (RelayMatrix),
•
automatic auto reclosing (optional),
•
free assignment of protective function for every re-
closing separately adjustable,
•
Free assignment of the input function to the digtial
input,
•
Saving of trip values and the switch-off times (t
CBFP
) of
25 fault events (voltage fail-safe),
•
Recording of up to 8 fault events with time stamp,
•
Display of date and time,
•
Trip via digital inputs,
•
Rack mounting, with self-acting short-circuit mecha-
nism for CT circuits,
•
Possibility of serial data exchange via the RS485 in-
terface, optionally with SEG RS485 Pro-Open-Data
Protocol or Modbus Protocol.
