Seg HighTECH Line User manual

MRI1
PROTECTION TECHNOLOGY
MADE SIMPLE
DIGITAL MULTIFUNCTIONAL RELAY FOR
TIME-OVERCURRENT PROTECTION
HighTECH Line
DIGITAL MULTIFUNCTIONAL RELAY FOR TIME-OVERCURRENT PROTECTION
Revision: A
Original document
English
MANUAL

2 TD_MRI1_06.05_GB
1 Introduction and application
2 Features and characteristics
3 Design
3.1 Connections
3.1.1 Analog input circuits
3.1.2 Output relays of MRI1-relays
3.1.3 Blocking input
3.1.4 External reset input
3.2 Relay output contacts
3.2.1 Parameter settings
3.3 LEDs
4 Working principle
4.1 Analog circuits
4.2 Digital circuits
4.3 Directional feature
4.4 Earth fault protection
4.4.1 Generator stator earth fault protection
4.4.2 System earth fault protection
4.5 Earth-fault directional feature
(ER/XR-relay type)
4.6 Determining earth short-circuit fault
direction
4.7 Demand imposed on the main current
transformers
5 Operation and setting
5.1 Display
5.2 Setting procedure
5.2.1 Pickup current for phase overcurrent
element (I>)
5.2.2 Time current characteristics for phase
overcurrent element (CHAR I>)
5.2.3 Trip delay or time multiplier for phase
overcurrent element (t
I>
)
5.2.4 Reset setting for inverse time tripping
characteristics in the phase current path
5.2.5 Current setting for high set element (I>>)
5.2.6 Trip delay for high set element (t
I>>
)
5.2.7 Relay characteristic angle RCA
5.2.8 Voltage transformer connection for residual
voltage measuring (3pha/e-n/1:1)
5.2.9 Pickup value for residual voltage U
E
(ER/XR-relay type)
5.2.10 Pickup current for earth fault element (I
E>
)
5.2.11 WARN/TRIP changeover
(E/X and ER/XR-relay type)
5.2.12 Time current characteristics for earth fault
element (CHAR IE; (not for ER/XR-relay type)
5.2.13 Trip delay or time multiplier for earth fault
element (t
IE>>
)
5.2.14 Reset mode for inverse time tripping in
earth current path
5.2.15 Current setting for high set element of earth
fault supervision (I
E>>
)
5.2.16 Trip delay for high set element of earth
fault supervision (t
IE>>
)
5.2.17 COS/SIN Measurement (ER/XR-relay type)
5.2.18 SOLI/RESI changeover (SR-relay type)
5.2.19 Circuit breaker failure protection t
CBFP
5.2.20 Nominal frequency
5.2.21 Display of the activation storage
(FLSH/NOFL)
5.2.22 Adjustment of the slave address
5.2.23 Setting of Baud-rate (applies for Modbus
Protocol only)
5.2.24 Setting of parity (applies for Modbus
Protocol only)
5.2.25 Blocking the protection functions and
assignment of the output relays
5.3 Setting value calculation
5.3.1 Definite time overcurrent element
5.3.2 Inverse time overcurrent element
5.4 Indication of measuring and fault values
5.4.1 Indication of measuring values
5.4.2 Indication of fault data
5.4.3 Fault memory (not for ER/XR types)
5.5 Reset
6 Relay testing and commissioning
6.1 Power-On
6.2 Testing the output relays and LEDs
6.3 Checking the set values
6.4 Secondary injection test
6.4.1 Test equipment
6.4.2 Example of test circuit for MRI1 relays
without directional feature
6.4.3 Checking the input circuits and measured
values
6.4.4 Checking the operating and resetting
values of the relay
6.4.5 Checking the relay operating time
6.4.6 Checking the high set element of the relay
6.4.7 Example of a test circuit for MRI1 relay
with directional feature
6.4.8 Test circuit earth fault directional feature
6.4.9 Checking the external blocking and reset
functions
6.4.10 Test of the CB failure protection
6.5 Primary injection test
6.6 Maintenance

TD_MRI1_06.05_GB 3
7 Technical data
7.1 Measuring input circuits
7.2 Common data
7.3 Setting ranges and steps
7.3.1 Time overcurrent protection (I-Type)
7.3.2 Earth fault protection (SR-Type)
7.3.3 Earth fault protection (E/X-Type)
7.3.4 Earth fault protection (ER/XR-Type)
7.3.5 Switch failure protection
7.3.6 Interface parameter
7.3.7 Inverse time overcurrent protection relay
7.3.8 Direction unit for phase overcurrent relay
7.3.9 Determination of earth fault direction
(MRl1-ER/XR)
7.3.10 Determination of earth fault direction
(MRl1-SR)
7.4 Inverse time characteristics
7.5 Output contacts
8 Order form

4 TD_MRI1_06.05_GB
1 Introduction and application
The MRl1 digital multifunctional relay is a universal
time overcurrent and earth fault protection device in-
tended for use in medium-voltage systems, either with
an isolated/compensated neutral point or for networks
with a solidly earthed/resistance-earthed neutral point.
• The protective functions of MRI1 which are imple-
mented in only one device are summarized as fol-
lows:
• Independent (Definite) time overcurrent relay.
• Inverse time overcurrent relay with selectable charac-
teristics.
• Integrated determination of fault direction for appli-
cation to doubly infeeded lines or meshed systems.
• Two-element (low and high set) earth fault protection
with definite or inverse time characteristics.
• Integrated determination of earth fault direction for
application to power system networks with isolated
or arc suppressing coil (Peterson coil) neutral
earthing. (ER/XR-relay type).
• Integrated determination of earth short-circuit fault di-
rection in systems with solidly-earthed neutral point or
in resistance-earthed systems (SR-relay type).
Furthermore, the relay MRI1 can be employed as a
back-up protection for distance and differential protec-
tive relays.
A similar, but simplified version of overcurrent relay
IRI1 with limited functions without display and serial in-
terface is also available.
Important:
For additional common data of all MR-relays please
refer to manual "MR - Digital Multifunctional relays".
On page 41 of this manual you can find the valid soft-
ware versions.
2 Features and characteristics
• 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
• Selectable protective functions between:
definite time overcurrent relay and
inverse time overcurrent relay
• Selectable inverse time characteristics according to
BS 142 and IEC 255-4:
Normal Inverse
Very Inverse
Extremely Inverse
• Reset setting for inverse time characteristics select-
able
• High set overcurrent unit with instantaneous or de-
finite time function.
• Two-element (low and high set) overcurrent relay
both for phase and earth faults.
• Directional feature for application to the doubly in-
feeded lines or meshed systems.
• Earth fault directional feature selectable for either iso-
lated or compensated networks.
• sensitive earth fault current measuring with or without
directional feature (X and XR-relay type
• Determination of earth short-circuit fault direction for
systems with solidly-earthed or resistance-earthed
neutral point.
• Numerical display of setting values, actual mea-
sured values and their active, reactive components,
memorized fault data, etc.
• Withdrawable modules with automatic short circuit
of C.T. inputs when modules are withdrawn.
• Blocking e.g. of high set element (e.g. for selective
fault detection through minor overcurrent protection
units after unsuccessful AR).
• Relay characteristic angle for phase current direc-
tional feature selectable
• Dwell time selectable
• Switch failure protection
• Storage of tripping values and shut-down times
(not ER/XR versions) (t
CBFP
) of eight failure events
• Free assignment of output relays
• Serial data exchange via RS485 interface possible;
alternatively with SEG RS485 Pro-Open Data Proto-
col or Modbus Protocol
• Suppression of indication after an activation
(LED flash)

TD_MRI1_06.05_GB 5
3 Design
3.1 Connections
Phase and earth current measuring:
Figure 3.1: Measuring of the phase currents for over-current-
and short-circuit protection (I>,I>>)
Figure 3.2: Earth-fault measuring by means of ring-core C.T. (I
E
)
When phase-- and earth-fault current measuring are
combined, the connection has to be realized as per
Figure 3.1 and Figure 3.2.
Figure 3.3: Phase current measuring and earth-current
detection by means of Holmgreen-circuit.
This connection can be used with three existing phase
current transformers when combined phase and earth-
current measuring is required.
Disadvantage of holmgreen-circuit:
At saturation of one or more C.Ts the relay detects
seeming an earth current.
* This arrow shows the current flow in forward direction, for this LED →← lights up green

6 TD_MRI1_06.05_GB
Voltage measuring for the directional detection:
Figure 3.4: Measuring of the phase voltages for the directional
detection at overcurrent, short-circuit or earth-fault
protection (I>, I>>, I
E>
and I
E>>
).
For details on the connection of ER/XR-unit type c.t.s,
see para 4.5.
I>
I>
I>
A3 L1
U1
U2
A5 L2
A7 L3
A2 N
U3
L
1
L2
L3
a
b
c
Figure 3.5: Voltage transformer in V-connection for the
directional detection at overcurrent and short-circuit
protection.
The V-connection can not be applied at earth fault di-
rectional feature.
3.1.1 Analog input circuits
The protection unit receives the analog input signals of
the phase currents IL1 (B3-B4), IL2 (B5-B6), IL3 B7-B8)
and the current IE (B1-B2), phase voltages U1 (A3),
U2 (A5), U3 (A7) with A2 as star point, each via
separate input transformers.
The constantly detected current measuring values are
galvanically decoupled, filtered and finally fed to the
analog/digital converter.
For the unit type with earth fault directional features
(ER/XR-relay type) the residual voltage U
E
in the sec-
ondary circuit of the voltage transformers is internally
formed.
In case no directional feature for the phase current
path is necessary the residual voltage from the open
delta winding can directly be connected to A3 and
A2.
See Chapter 4.4 for voltage transformer connections
on isolated/compensated systems.
3.1.2 Output relays of MRI1-relays
The MRI1 is equipped with 5 output relays. Apart from
the relay for self-supervision, all protective functions
can be optionally assigned:
• Relay 1: C1, D1, E1 and C2, D2, E2
• Relay 2: C3, D3, E3 and C4, D4, E4
• Relay 3: C5, D5, E5
• Relay 4: C6, D6, E6
• Self-supervision C7, D7, E7
All trip and alarm relays are working current relays,
the relay for self supervision is an idle current relay.
3.1.3 Blocking input
The blocking functions adjusted before will be blocked
if an auxiliary voltage is connected to (terminals)
D8/E8. (See chapter 5.2.25)
3.1.4 External reset input
Please refer to chapter 5.5.

TD_MRI1_06.05_GB 7
3.2 Relay output contacts
Figure 3.6
Contacts at MRI1:
To prevent that the C.B. trip coil circuit is interrupted
by the MRI1 first, i.e. before interruption by the C.B.
auxiliary contact, a dwell time is fixed.
This setting ensures that the MRI1 remains in self hold-
ing for 200ms after the fault current is interrupted.

8 TD_MRI1_06.05_GB
3.2.1 Parameter settings (see chapter 5)
Relay-type MRI1- IIE
IX
IRE
IRX
IR IER
IXR
IRER
IRXR
ER
XR
E
X
ISR IRSR SR
I> X X X X X X X X
CHAR I> X X X X X X X X
t
I>
X X X X X X X X
0s / 60s
3)
X X X X X X X X
I>> X X X X X X X X
t
I>>
X X X X X X X X
RCA X X X X
1:1 / 3 pha / e-n X X X
U
E
X X X
I
E>
X X X X X X X X X
warn/trip X X X X X X
CHAR I
E
X X X X X X
t
IE
X X X X X X X X X
0s/60 s
4)
X X X X X X
I
E>>
X X X X X X X X X
t
IE>>
X X X X X X X X X
sin/cos X X X
soli/resi XXX
tCBFP X X X X X X X X X X X
50/60 Hz X X X X X X X X X X X
LED-Flash X X X X X X X X X X X
RS485/Slaveaddress X X X X X X X X X X X
Baud-Rate
3)
X X X X X X X X X X X
Parity-Check
3)
X X X X X X X X X X X
Table 3.1: Parameters of the different relay types.
1)
Reset setting for inverse time characteristics in phase current path
2)
Reset setting for inverse time characteristics in earth current path
3)
Only devices with Modbus-Protocol
Additional parameters:
Relay-type MRI1- I IE
IX
IRE
IRX
IR IER
IXR
IRER
IRXR
ER
XR
E
X
ISR IRSR SR
Blocking mode X X X X X X X X X X X
Relay parameterising X X X X X X X X X X X
Fault recorder X X X X X X X X

TD_MRI1_06.05_GB 9
SELECT/RESET
ENTER
TRIP
t
I
MRI1-I
PHASE
tI>>
I>>
tI>
CHAR I>
I>
L1 L2 L3
RS DISPLAY
Figure 3.7: Front panel MRI1-I
MRI1-E
SELECT/RESET
ENTER
TRIP
t
I
I >
E
CHAR I
tE
I >
I >>
EtI >>
EEARTH
E
RS
E
DISPLAY
Figure 3.8: Front panel MRI1-E/X
SELECT/RESET
ENTER
TRIP
t
I
I>
CHAR I>
tI>
I>>
tI>> PHASE
MRI1-IR
L1 L2 L3
RS
Q
I
P
IDISPLAY
Figure 3.9 Front panel MRI1-IR
MRI1-ER
t
I >
E
U >
E
tI >
E
I >>
E
tI >>
EEARTH
I
E
RS
QP
II
SELECT/RESET
ENTER
TRIP
DISPLAY
Figure 3.10: Front panel MRI1-ER/XR

10 TD_MRI1_06.05_GB
SELECT/RESET
ENTER
TRIP
t
I
I >
E
CHAR IE
tE
I >
I >>
EtI >>
EEARTH
MRI1-SR
E
RSIQ
IPDISPLAY
Figure 3.11: Front panel MRI1-SR
SELECT/RESET
ENTER
TRIP
t
I
MRI1-IRER
L1 L2 L3 E
RS
Q
I
P
I
PHASE
EARTH
I >
E
I >>
E
tI >>
E
tI>>
I>>
I>
t
CHAR I>
I>
tI >
E
U >
E
Figure 3.12: Front panel MRI1-IRER/IRXR
and MRI1-IER/IXR
3.3 LEDs
The LEDs left from the display are partially bi-colored,
the green indicating measuring, and the red fault indi-
cation.
MRI1 with directional addition have a LED (green- and
red arrow) for the directional display. At pickup/trip
and parameter setting the green LED lights up to indi-
cate the forward direction, the red LED indicates the
reverse direction.
The LED marked with letters RS lights up during setting
of the slave address of the device for serial data com-
munication.
The LEDs arranged at the characteristic points on the
setting curves support the comfortable setting menu se-
lection. In accordance with the display 5 LEDs for
phase fault overcurrent relay and 5 LEDs for earth-fault
relay indicate the corresponding menu point selected.
SELECT/RESET
ENTER
TRIP
t
I
MRI1-IRSR
L1 L2 L3 E
RS
Q
I
P
I
PHASE
EARTH
I >>
E
I>>
I>
I >
E
CHAR I
t
I >
E
I >>
E
t
t
I>>
I>
t
CHAR I>
E
Figure 3.13: Front panel MRI1-IRSR; MRI1-IRE/IRX
and MRI1-ISR

TD_MRI1_06.05_GB 11
4 Working principle
4.1 Analog circuits
The incoming currents from the main current transform-
ers on the protected object are converted to voltage
signals in proportion to the currents via the input trans-
formers and burden. The noise signals caused by in-
ductive and capacitive coupling are supressed by an
analog R-C filter circuit.
The analog voltage signals are fed to the A/D-
converter of the microprocessor and transformed to
digital signals through Sample- and Hold-circuits. The
analog signals are sampled at 50 Hz (60 Hz) with a
sampling frequency of 800 Hz (960 Hz), namely, a
sampling rate of 1.25 ms (1.04 ms) for every measur-
ing quantity. (16 scans per period).
Figure 4.1: Block diagram
4.2 Digital circuits
The essential part of the MRI1 relay is a powerful mi-
crocontroller. All of the operations, from the analog
digital conversion to the relay trip decision, are carried
out by the microcontroller digitally. The relay program
is located in an EPROM (Electrically-Programmable-
Read-Only-Memory). With this program the CPU of the
microcontroller calculates the three phase currents and
ground current in order to detect a possible fault situa-
tion in the protected object.
For the calculation of the current value an efficient digi-
tal filter based on the Fourier Transformation (DFFT -
Discrete Fast Fourier Transformation) is applied to sup-
press high frequency harmonics and DC components
caused by fault-induced transients or other system dis-
turbances.
The calculated actual current values are compared
with the relay settings. If a phase current exceeds the
pickup value, an alarm is given and after the set trip
delay has elapsed, the corresponding trip relay is ac-
tivated.
The relay setting values for all parameters are stored in
a parameter memory (EEPROM - Electrically Erasable
Programmable Read-only Memory), so that the actual
relay settings cannot be lost, even if the power supply
is interrupted.
The microprocessor is supervised by a built-in "watch-
dog" timer. In case of a failure the watchdog timer re-
sets the microprocessor and gives an alarm signal, via
the output relay "self supervision".
4.3 Directional feature
A built-in directional element in MRI1 is available for
application to doubly infeeded lines or to ring net-
works.
The measuring principle for determining the direction is
based on phase angle measurement and therefore
also on coincidence time measurement between cur-
rent and voltage. Since the necessary phase voltage
for determining the direction is frequently not available
in the event of a fault, whichever line-to-line voltage fol-
lows the faulty phase by 90° is used as the reference
voltage for the phase current. The characteristic angle
at which the greatest measuring sensitivity is achieved
can be set to precede the reference voltage in the
range from 15° to 83°.
Figure 4.2: Relay characteristic angle
The TRIP region of the directional element is deter-
mined by rotating the phasor on the maximum sensitiv-
ity angle for ±90°, so that a reliable direction deci-
sion can be achieved in all faulty cases.

12 TD_MRI1_06.05_GB
If line impedance and internal resistance of the gen-
erator is only ohmic:
If line impedance and internal resistance of the gen-
erator is only inductive:
The maximum sensitivity angle corresponds to the R/L
component.
Figure 4.3: TRIP/NO-TRIP region for directional element in
MRI1. In this case the advance direction is
defined as TRIP region and the reverse direction
as NO-TRIP region.
By means of accurate hardware design and by using
an efficient directional algorithm a high sensitivity for
the voltage sensing circuit and a high accuracy for
phase angle measurement are achieved so that a cor-
rect directional decision can be made even by close
three-phase faults.
As an addition, to avoid maloperations due to distur-
bances, at least 2 periods (40 ms at 50 Hz) are
evaluated.
For the MRI1-overcurrent relays with directional feature
different time delays or time multipliers can be set for
forward and backward faults (ref. to chapter 5.2.3
and 5.2.6).
If the trip delay for backward faults is set longer than
the one for forward faults, the protective relay works
as a "backup"-relay for the other lines on the same
busbar. This means that the relay can clear a fault in
the backward direction with a longer time delay in
case of refusal of the relay or the circuit breaker on the
faulted line.
If the trip delay for backward faults is set out of range
(on the display "EXIT"), the relay will not trip in case of
backward faults.
The assignment of the output relays can be used to se-
lect in which direction the failure is to be indicated (re-
fer also to Chapter 5.2.15). It is possible to indicate
the activation and/or the tripping for each tripping di-
rection via the output relays.

TD_MRI1_06.05_GB 13
4.4 Earth fault protection
4.4.1 Generator stator earth fault
protection
With the generator neutral point earthed as shown in
figure 4.4 the MRI1 picks up only to phase earth faults
between the generator and the location of the current
transformers supplying the relay.
Earth faults beyond the current transformers, i.e. on the
consumer or line side, will not be detected.
Figure 4.4: Generator stator earth fault protetion
4.4.2 System earth fault protection
With the generator neutral point earthed as shown in
figure 4.5, the MRI1 picks up only to earth faults in the
power system connected to the generator. It does not
pick up to earth faults on the generator terminals or in
generator stator.
Figure 4.5: System earth fault protection

14 TD_MRI1_06.05_GB
4.5 Earth-fault directional feature
(ER/XR-relay type)
A built-in earth-fault directional element is available for
applications to power networks with isolated or with
arc suppressing coil compensated neutral point.
For earth-fault direction detection it is mainly the ques-
tion to evaluate the power flow direction in zero se-
quence system. Both the residual voltage and neutral
(residual) current on the protected line are evaluated to
ensure a correct direction decision.
In isolated or compensated systems, measurement of
reactive or active power is decisive for earth-fault de-
tection. It is therefore necessary to set the ER/XR-relay
type to measure according to sin ϕor cos ϕmethods,
depending on the neutral-point connection method.
The residual voltage U
E
required for determining earth
fault direction can be measured in three different
ways, depending on the voltage transformer connec-
tions.
(refer to Table 4.1:)Total current can be measured by
connecting the unit either to a ring core C.T. or to cur-
rent transformers in a Holmgreen circuit. However,
maximum sensitivity is achieved if the MRl1 protective
device is connected to a ring core C. T. (see Figure
3.2).
The pick-up values I
E>
and I
E>>
(active or reactive cur-
rent component for cos ϕor sin ϕmethod) for ER-relay
types can be adjusted from 0.01 to 0.45 x I
N
. For re-
lay type MRI1-XR these pick-up values can be ad-
justed from 0.1 to 4.5 % I
N
.
Adjustment
possibility
Application Voltage transformer
connections
Measurd
voltage at
earth fault
Correction fac-
tor for residual
voltage
“3pha”
3-phase voltage
transformer connected
to terminals A3, A5,
A7, A2
(MRI1-IRER;
MRI1-IER;
MRI1-ER/XR)
√3 x U
N
= 3 x U
1N
K = 1 / 3
“e-n”
e-n winding
connected to
terminals A3, A2
(MRI1-IER;
MRI1-ER/XR)
U
N
= √3 x U
1N
K = 1 / √3
“1:1”
Neutral-point voltage
(= residual voltage)
terminals A3, A2
(MRI1-IER;
MRI1-ER/XR)
U
1N
= U
NE
K = 1
Table 4.1:

TD_MRI1_06.05_GB 15
Figure 4.6: Phase position between the residual voltage and zero sequence current for faulted and non-faulted lines in case of isolated
systems (sin
ϕ )
U
E
- residual voltage
I
E
- zero sequence current
I
C
- capacitive component of zero sequence cur-
rent
I
W
- resistive component of zero sequence current
By calculating the reactive current component (sin ϕ
adjustment) and then comparing the phase angle in
relation to the residual voltage U
E
, the ER/XR-relay
type determines whether the line to be protected is
earth-faulted.
On non-earth-faulted lines, the capacitive compo-
nent Ic(a) of the total current precedes the residual
voltage by an angle of 90°. In case of a faulty line
the capacity current I
C(b)
lags behind the residual
voltage at 90°.
Figure 4.7: Phase position between the residual voltage and zero sequence current for faulted and non-faulted lines in case of
compensated systems (cos
ϕ )
U
E
- residual voltage
I
E
- zero sequence current
I
L
- inductive component of zero sequence current
(caused by Petersen coil)
I
C
- capacitive component of zero sequence current
I
W
- resistive component of zero sequence current
In compensated mains the earth fault direction cannot
be determined from the reactive current components
because the reactive part of the earth current depends
upon the compensation level of the mains. The ohmic
component of the total current (calculated by cos ϕad-
justment) is used in order to determine the direction.
The resistive component in the non-faulted line is in
phase with the residual voltage, while the resistive
component in the faulted line is opposite in phase with
the residual voltage.
By means of an efficient digital filter harmonics and
fault transients in the fault current are suppressed. Thus,
the uneven harmonics which, for instance, are caused
an electric arc fault, do not impair the protective func-
tion.

16 TB MRI1 09.00 E
4.6 Determining earth short-circuit
fault direction
The SR-relay type is used in solidly-earthed or resis-
tance-earthed systems for determining earth short-circuit
fault direction. The measuring principle for determining
the direction is based on phase angle measurement
and therefore also on the coincidence-time measure-
ment between earth current and zero sequence volt-
age.
The zero sequence voltage U
0
required for determining
the earth short-circuit fault direction is generated inter-
nally in the secondary circuit of the voltage transform-
ers.
With SR/ISR-relay types the zero sequence voltage U
0
can be measured directly at the open delta winding
(e-n). Connection A3/A2.
Most faults in a characteristic angle are predominantly
inductive in character. The characteristic angle be-
tween current and voltage at which the greatest meas-
uring sensitivity is achieved has therefore been se-
lected to precede zero sequence voltage U
0
by 110°.
Figure 4.8: Characteristic angle in solidly earthed-systems (SOLI)
Most faults in a resistance-earthed system are pre-
dominantly ohmic in character, with a small inductive
part. The characteristic angle for these types of system
has therefore been set at +170° in relation to the zero
sequence voltage U
0
(see Figure 4.9).
Figure 4.9: Characteristic angle in resistance-earthed systems (RESI)
The pickup range of the directional element is set by
turning the current indicator at the characteristic angle
through + 90°, to ensure reliable determination of the
direction.
4.7 Demand imposed on the main
current transformers
The current transformers have to be rated in such a
way, that a saturation should not occur within the fol-
lowing operating current ranges:
Independent time overcurrent function: K1 = 2
Inverse time overcurrent function: K1 = 20
High-set function: K1 = 1.2 - 1.5
K1 = Current factor related to set value
Moreover, the current transformers have to be rated
according to the maximum expected short circuit cur-
rent in the network or in the protected objects.
The low power consumption in the current circuit of
MRI1, namely <0,2 VA, has a positive effect on the
selection of current transformers. It implies that, if an
electromechanical relay is replaced by MRI1, a high
accuracy limit factor is automatically obtained by us-
ing the same current transformer.

TD_MRI1_06.05_GB 17
5 Operation and setting
5.1 Display
Function Display shows Pressed push button Corresponding LED
Normal operation SEG
Measured operating values Actual measured values,
(related to IN; UE1))
(XR-type related to % IN)
<SELECT/RESET>
one time for each
L1, L2, L3, E, UE>, IE>
Measuring range overflow max. <SELECT/RESET> L1, L2, L3, E
Setting values:
phase (I>; CHAR I>; tI>; I>>; tI>>)
earth (IE>; CHAR IE; tIE>; IE>>; tIE>>; UE>)
Current settings
Trip delay
Characteristics
<SELECT/RESET>
one time for each
parameter
I >; CHAR I>; tI>; I>>;
tI>>; LED →←
IE>;CHAR IE; tIE> ;IE>> ;
tIE>>;UE>
Reset setting (only available at inverse
time characteristics)
0s / 60s <SELECT/RESET>
<+><->
I>; CHAR I>; tI>
IE>; CHAR IE>; tIE>
Relay characteristic angle for pase cur-
rent directional feature
RCA in degree (°) <SELECT/RESET>
<+><->
LED →← (green)
Warning reverse direction 1)
no warning
warning
NOWA
WBAK
<SELECT/RESET>
LED →← (red) + I>
LED →← (red) + IE>
Warning or Trip at earth fault
measuring (E- and ER/XR-types)
TRIP
WARN
<SELECT/RESET>
<+><->
IE>
Measured method of the residual
voltage UE1)
3 PHA ; E-N ; 1:1 <SELECT/RESET>
<+><->
UE>
residual voltage setting voltage in volts <SELECT/RESET><+><-> UE>
changeover of isolated (sin ϕ)
or compensated (cos ϕ)
networks (for ER/XR-type)
SIN
COS
<SELECT/RESET>
<+><->
Change over of solidly/resistance
earthed networks (SR-type)
SOLI
RESI
<SELECT/RESET>
<+><->
Switch failure protection tCBFP <SELECT/RESET> <+><->
Tripping protection
switch failure protection
CBFP After fault tripping
Nominal frequency f=50 / f=60 <SELECT/RESET><+><->
Switch-over LED flash
No LED flash
FLSH
NOFL
<SELECT/RESET>
<+><->
Blocking of function EXIT <+> until max. setting value LED of blocked
parameter
Slave address of serial interface 1 - 32 <SELECT/RESET>
<+><->
RS
Baud-Rate 2) 1200-9600 <SELECT/RESET> <+><-> RS
Parity-Check even odd no <SELECT/RESET> <+><-> RS
Recorded fault data Tripping currents and other
fault data
<SELECT/RESET>
one time for each phase
L1, L2, L3, E
I>, I>>, IE>, IE>>, UE>
Save parameter? SAV? <ENTER>
Delete failure memory wait <-> <SELECT/RESET>
Enquiry failure memory FLT1; FLT2..... <-><+> L1, L2, L3, E
I>, I>>, IE>, IE>>,
Save parameter! SAV! <ENTER> for about 3 s
Software version First part (e.g. D01-)
Sec. part (e.g. 8.00)
<TRIP>
one time for each part
Manual trip TRI? <TRIP> three times
Inquire password PSW? <TRIP><ENTER>
Relay tripped TRIP <TRIP>
or after fault tripping
Secret password input XXXX <SELECT/RESET>
<+><-><ENTER>
System reset SEG <SELECT/RESET>
for about 3 s
Table 5.1: possible indication messages on the display
1)
refer to 4.4
2)
only Modbus

18 TB MRI1 09.00 E
5.2 Setting procedure
After push button <SELECT/RESET> has been pressed,
always the next measuring value is indicated. Firstly
the operating measuring values are indicated and then
the setting parameters. By pressing the <ENTER> push
button the setting values can directly be called up and
changed.
5.2.1 Pickup current for phase ‘
overcurrent element (I>)
The setting value for this parameter that appears on
the display is related to the nominal current (I
N
) of the
relay. This means: pickup current (Is) = displayed value
x nominal current (I
N
)e.g. displayed value = 1.25
then, Is = 1.25 x IN.
5.2.2 Time current characteristics for
phase overcurrent element
(CHAR I>)
By setting this parameter, one of the following 4 mes-
sages appears on the display:
DEFT - Definite Time
NINV - Normal Inverse
VINV - Very Inverse
EINV - Extremely Inverse
Anyone of these four characteristics can be chosen by
using <+> <->-push buttons, and can be stored by us-
ing <ENTER>-push button.
5.2.3 Trip delay or time multiplier for
phase overcurrent element (t
I>
)
Usually, after the characteristic is changed, the time
delay or the time multiplier should be changed accord-
ingly. In order to avoid an unsuitable arrangement of
relay modes due to carelessness of the operator, the
following precautions are taken:
After the characteristic setting, the setting process turns
to the time delay setting automatically. The LED tI> is
going to flash yellow to remind the operator to change
the time delay setting accordingly. After pressing the
<SELECT>-push button, the present time delay setting
value is shown on the display. The new setting value
can then be changed by using <+> <-> -push buttons.
If, through a new setting, another relay characteristic
other than the old one has been chosen (e.g. from
DEFT to NINV), but the time delay setting has not been
changed despite the warning from the flashing LED,
the relay will be set to the most sensitive time setting
value of the selected characteristics after five minutes
warning of flashing LED tI>. The most sensitive time set-
ting value means the fastest tripping for the selected re-
lay characteristic. When the time delay or the time
multiplier is set out of range (Text "EXIT" appears on the
display), the low set element of the overcurrent relay is
blocked. The "WARN"-relay will not be blocked.
For the MRI1-version with directional feature, the dif-
ferent trip time delays or the time multipliers can be
chosen for forward and backward faults.
By setting the trip delay, the actual set value for for-
ward faults appears on the display first and the LED
under the arrows is alight green. It can be changed
with push button <+> <-> and then stored with push
button <ENTER>. After that, the actual trip delay (or
time multiplier) for backward faults appears on the
display by pressing push button <SELECT> and the
LED under the arrows is alight red.
Usually this set value should be set longer than the one
for forward faults, so that the relay obtains its selectiv-
ity during forward faults. If the time delays are set
equally for both forward and backward faults, the re-
lay trips in both cases with the same time delay,
namely without directional feature.
Note:
When selecting dependent tripping characteristics at
relays with directional phase current detection, atten-
tion must be paid that a clear directional detection will
be assured only after expiry of 40 ms.

TD_MRI1_06.05_GB 19
5.2.4 Reset setting for inverse time
tripping characteristics in the phase
current path
To ensure tripping, even with recurring fault pulses
shorter than the set trip delay, the reset mode for in-
verse time tripping characteristics can be switched
over. If the adjustment tRST is set at 60s, the tripping
time is only reset after 60s faultless condition. This
function is not available if tRST is set to 0. With fault
current cease the trip delay is reset immediately and
started again at recurring fault current.
5.2.5 Current setting for high set element
(I>>)
The current setting value of this parameter appearing
on the display is related to the nominal current of the
relay
This means: I>> = displayed value x I
N
.
When the current setting for high set element is set out
of range (on display appears "EXIT"), the high set ele-
ment of the overcurrent relay is blocked.
The high set element can be blocked via terminals
E8/D8 if the corresponding blocking parameter is set
to bloc (refer to chapter 5.2.25).
5.2.6 Trip delay for high set element (t
I>>
)
Independent from the chosen tripping characteristic for
I>, the high set element I>> has always a definite-time
tripping characteristic. An indication value in seconds
appears on the display.
The setting procedure for forward- or backward faults,
described in chapter 5.2.3, is also valid for the trip-
ping time of the high set element.
5.2.7 Relay characteristic angle RCA
The characteristic angle for directional feature in the
phase current path can be set by parameter RCA to
15°, 27°, 38°, 49°, 61°, 72° or 83°, leading to the
respective reference voltage (see chapter 4.3).
5.2.8 Voltage transformer connection for
residual voltage measuring
(3pha/e-n/1:1)
Depending on the connection of the voltage trans-
former of ER/XR-relay types three possibilities of the
residual voltage measurement can be chosen
(see chapter 4.4)
5.2.9 Pickup value for residual voltage
U
E
(ER/XR-relay type)
Regardless of the preset earth current, an earth fault is
only identified if the residual voltage exceeds the set
reference value. This value is indicated in volt.
5.2.10 Pickup current for earth fault
element (I
E>
)
(Similar to chapter 5.2.1)
The pickup value of X and XR-relay type relates to % I
N
.
5.2.11 WARN/TRIP changeover
(E/X and ER/XR-relay type)
A detected earth fault can be parameterized as fol-
lows:
a) "warn" only the alarm relay trips
b) "TRIP" the trip relay trips and tripping values are
stored.
5.2.12 Time current characteristics for
earth fault element (CHAR IE;
(not for ER/XR-relay type)
(Similar to chapter 5.2.2)
5.2.13 Trip delay or time multiplier for
earth fault element (t
IE>>
)
(Similar to chapter 5.2.3)
5.2.14 Reset mode for inverse time
tripping in earth current path
(Similar to chapter 5.2.4)

20 TD_MRI1_06.05_GB
5.2.15 Current setting for high set element
of earth fault supervision (I
E>>
)
(Similar to chapter 5.2.5)
The pickup value of X and XR-relay type relates to % I
N
.
5.2.16 Trip delay for high set element
of earth fault supervision (t
IE>>
)
(Similar to chapter 5.2.6)
5.2.17 COS/SIN Measurement
(ER/XR-relay type)
Depending on the neutral earthing connection of the
protected system the directional element of the earth
fault relay must be preset to cos ϕor sin ϕmeasure-
ment.
By pressing <SELECT> the display shows "COS" resp.
"SIN". The desired measuring principle can be se-
lected by <+> or <-> and must be entered with pass-
word.
5.2.18 SOLI/RESI changeover
(SR-relay type)
Depending on the method of neutral-point connection
of the system to be protected, the directional element
for the earth-current circuit must be set to "SOLI" (= sol-
idly earthed) or "RESI" = (resistance earthed).
5.2.19 Circuit breaker failure protection
t
CBFP
The CB failure protection is based on supervision of
phase currents during tripping events. Only after trip-
ping this protective function becomes active. The test
criterion is whether all phase currents are dropped to
<1% x I
N
within t
CBFP
(Circuit Breaker Failure Protection -
adjustable between 0.1 - 1.6s). If not all of the phase
currents have dropped to <1%xI
N
within this time, CB
failure is detected and the related relay activated. The
CB failure protection function is deactivated again as
soon as the phase currents have dropped to <1%xI
N
within t
CBFP
5.2.20 Nominal frequency
The adapted FFT-algorithm requires the nominal fre-
quency as a parameter for correct digital sampling
and filtering of the input currents.
By pressing <SELECT> the display shows "f=50" or
"f=60". The desired nominal frequency can be ad-
justed by <+> or <-> and then stored with <ENTER>.
5.2.21 Display of the activation storage
(FLSH/NOFL)
If after an activation the existing current drops again
below the pickup value, e.g. I>, without a trip has
been initiated, LED I> signals that an activation has
occured by flashing fast. The LED keeps flashing until it
is reset again (push button <RESET>). Flashing can be
suppressed when the parameter is set to NOFL.
5.2.22 Adjustment of the slave address
Pressing push buttons <+> and <-> the slave ad-
dresscan be set in range of 1-32.
5.2.23 Setting of Baud-rate (applies for
Modbus Protocol only)
Different transmission rates (Baud rate) can be set for
data transmission via Modbus protokol.
The rate can be changed by push buttons <+> and
<-> and saved by pressing <ENTER>.
5.2.24 Setting of parity (applies for
Modbus Protocol only)
The following three parity settings are possible :
• "EVN" = even
• "ODD" = odd
• "NO" = no parity check
The setting can be changed by push buttons <+> and
<-> and saved by pressing <ENTER>.