Seg High Tech MRI3-ITE User manual

MRI3-ITE(R) -Time overcurrent relay with thermal replica
and earth current measuring

2TB MRI3-ITE(R) 12.00 E
Contents
1 Introduction and Application
2 Features and characteristics
3Design
3.1 Connections
3.1.1 Analog input circuits
3.1.2 Output relays
3.2 Relay output contacts
3.2.1 Blocking input
3.2.2 External reset input
3.2.3 Fault recorder
3.3 Front plate
4 Working principle
4.1 Analog circuits
4.2 Digital circuits
4.3 Thermal replica
4.3.1 Definitions
4.4 Algorithm
4.5 Earth fault protection
4.5.1 Generator stator earth fault protection
4.5.2 System earth fault protection
4.6 Earth-fault directional feature
(ER-relay type)
4.7 Demand imposed on the main current
transformers
5 Operation and settings
5.1 Display
5.1.1 LEDs
5.2 Setting procedure
5.3 System parameter
5.3.1 Display of measuring values as primary
quantities (Iprim phase)
5.3.2 Display of earth current as primary
quantity (Iprim earth)
5.3.3 Display of residual voltage UE as primary
quantity (Uprim/Usec)
5.3.4 Voltage transformer connection for resi-
dual voltage measuring (3pha/e-n/1:1)
5.3.5 Nominal frequency
5.3.6 Display of the activation storage
(FLSH/NOFL)
5.3.7 Parameter switch/external triggering of
the fault recorder
5.4 Protection parameters
5.4.1 Pickup value of the thermal overload
protection IB,A and IB,T
5.4.2 Constant k
5.4.3 Time constant τ
5.4.4 Pickup current for phase overcurrent
element (I>)
5.4.5 Time current characteristics for phase
overcurrent element (CHAR I>)
5.4.6 Trip delay or time multiplier for phase
overcurrent element (tI>)
5.4.7 Reset setting for inverse time tripping
characteristics in the phase current path
5.4.8 Current setting for high set element (I>>)
5.4.9 Trip delay for high set element (tI>>)
5.4.10 Pickup value for residual voltage UE
(ITER-relay type)
5.4.11 Pickup current for earth fault element (IE>)
5.4.12 WARN/TRIP changeover
5.4.13 Time current characteristics for earth fault
element (CHAR IE) (not ER device type)
5.4.14 Trip delay or time multiplier for earth fault
element (tIE>)
5.4.15 Resetting time for inverse time earth fault
element (not ER-relay type
5.4.16 Current setting for high set element of
earth fault supervision (IE>>)
5.4.17 Trip delay for high set element of earth
fault supervision (tIE>>)
5.4.18 COS/SIN Measurement (ER - relay type)
5.4.19 Block/Trip – time (only ITE-device type)
5.4.20 Circuit breaker failure protection tCBFP
5.4.21 Adjustment of the slave address
5.4.22 Setting of Baud-rate (applies for Modbus
Protocol only)
5.4.23 Setting of parity (applies for Modbus
Protocol only)
5.5 Fault recorder
5.5.1 Adjustment of the fault recorder
5.5.2 Number of the fault recordings
5.5.3 Adjustment of trigger occurences
5.5.4 Pre-trigger time (Tpre)
5.6 Adjustment of the clock
5.7 Additional functions
5.7.1 Blocking of the protective functions
5.8 Indication of measuring and fault values
5.8.1 Indication of measuring values
5.8.2 Unit of the measuring values displayed
5.8.3 Indication of fault data
5.8.4 Fault memory
5.9 Reset
5.9.1 Erasure of fault storage
5.9.2 Reset of the thermal replica register

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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 MRI3-ITE
6.4.3 Checking the input circuits and measured
values
6.4.4 Example of a test circuit with earth fault
directional feature
6.4.5 Checking the operating and resetting
values of the relay
6.4.6 Checking the relay operating time
6.4.7 Checking the high set element of the
relay
6.4.8 Checking the external blocking and reset
functions
6.4.9 Testing the external blocking with
Block/Trip function
6.4.10 Test of the CB failure protection
6.5 Primary injection test
6.6 Maintenance
7 Technical data
7.1 Measuring circuits
7.2 Common data
7.3 Setting ranges and steps
7.3.1 Systemparameter
7.3.2 Time overcurrent protection and thermal
replica
7.3.3 Earth fault protection
7.3.4 Earth fault protection (ER-Type)
7.3.5 Determination of earth fault direction
(MRl3-ITER)
7.3.6 BlockTrip – time**
7.3.7 Switch failure protection
7.3.8 Interface parameter
7.3.9 Parameter for the fault recorder
7.4 Tripping characteristics
7.4.1 Thermal characteristic
7.4.2 Preload factor
7.4.3 Inverse time overcurrent protection relay
7.5 Tripping characteristics
7.6 Output relays
8 Order form

4TB MRI3-ITE(R) 12.00 E
1Introduction 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“.
2Features 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 (tCBFP) 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.

TB MRI3-ITE(R) 12.00 E 5
3Design
3.1 Connections
Figure 3.1: Connection diagram
P1
P2
S1
S2
P1
P2
S1
S2
P1
P2
S1
S2
I1
I2
I3
IE
L1.1
B3
B4 L1.2
L2.1
B5
L2.2
B6
L3.1
B7
L3.2B8
B1
B2
L
1
L2
L3
Figure 3.2: 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.
Figure 3.3: Earth-fault measuring by means of ring-core C.T. (IE)
When phase-- and earth-fault current measuring are
combined, the connection has to be realized as per
Figure 3.2 and Figure 3.3.

6TB MRI3-ITE(R) 12.00 E
Voltage measuring for the directional detection:
Figure 3.4: Measuring of the phase voltages for the directional
detection at earth-fault protection (IE> and IE>>).
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 residual current IE(B1-B2) each via separate
input transformers.
The constantly detected current measuring values are
galvanically decoupled, filtered and finally fed to the
analog/digital converter.
3.1.2 Output relays
Two relays are equipped with two change-over con-
tacts and three relays with each one change-over con-
tact for alarm. 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
•Relay 5: Self-supervision C7, D7, E7
All trip and alarm relays are working current relays, the
relay for self supervision is an idle current relay.
3.2 Relay output contacts
Figure 3.5: Relay outputs
3.2.1 Blocking input
The function for blocking can be parameterized arbi-
trary. When an auxiliary voltage is connected to
D8/E8 those relay functions will be blocked which
were parameterized before (see chapter 5.7.1).
3.2.2 External reset input
See chapter 5.9

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3.2.3 Fault recorder
The MRI3-ITER has a fault value recorder which rec-
ords the measured analog values as instantaneous
values.
The instantaneous values
iL1, iL2, iL3, iE,
are scanned at a raster of 1.25 ms (at 50 Hz) and
1.041 ms (at 60 Hz) and saved in a cyclic buffer. It is
possible to store 1 - 8 fault occurences with a total re-
cording time of 16 s (with 50 Hz) and 13.33 s (with
60 Hz) per channel.
Storage division
Independent of the recording time, the entire storage
capacity can be divided into several cases of distur-
bance with a shorter recording time each. In addition,
the deletion behaviour of the fault recorder can be in-
fluenced.
No writing over
If 2, 4 or 8 recordings are chosen, the complete
memory is divided into the relevant number of partial
segments. If this max. number of fault event has been
exceeded, the fault recorder block any further record-
ings in order to prevent that the stored data are written
over. After the data have been read and deleted, the
recorder to ready again for further action.
Writing over
If 1, 3 or 7 recordings are chosen, the relevant num-
ber of partial segments is reserved in the complete
memory. If the memory is full, a new recording will
always write over the oldest one.
The memory part of the fault recorder is designed as
circulating storage. In this example 7 fault records can
be stored (written over).
Memory space 6 to 4 is occupied.
Memory space 5 is currently being written in
Figure 3.6: Division of the memory into 8 segments, for example
Since memory spaces 6, 7 and 8 are occupied, this
example shows that the memory has been assigned
more than eight recordings. This means that No. 6 is
the oldest fault recording and No. 4 the most recent
one.
trigger occurence
recording duration
Tpre
[s]
Figure 3.7: Basic set-up of the fault recorder
Each memory segment has a specified storage time
which permits setting of a time prior to the trigger
event.
Via the interface RS485 the data can be read and
processed by means of a PC with HTL/PL-Soft4. The
data is graphically edited and displayed. Binary tracks
are recorded as well, e.g. activation and trip.

8TB MRI3-ITE(R) 12.00 E
3.3 Front plate
Figure 3.8: Front plate MRI3-ITE
Figure 3.9: Front plate MRI3-ITER
The LED RS, ϑAand ϑTyellow light up yellow (MRI3-ITE)
The LED RS, IPand IQlight up yellow (MRI3-ITER).
All other LEDs are two-coloured. LEDs left to the alpha-
numerical display light-up green during measuring and
red at alarm.
LEDs underneath the pushbutton <SELECT/RESET>
light-up green during setting and inquiry of the setting
values printed left to the LEDs. They light-up red when
the setting values printed at the right to the LEDs are
activated.
The LED labelled with the letters LR is alight while the
fault recorder is being adjusted.

TB MRI3-ITE(R) 12.00 E 9
4Working 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 RC 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.
4.2 Digital circuits
The essential part of the MRI3-ITE relay is a powerful
microcontroller. 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 in order to
detect a possible fault situation 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.
In case, the time for which a current was above the
preset pickup value, exceeds the trip delay or the
thermal capacity is reached, an alarm signal will be
given. Dependent on their adjustment the output relays
will also be activated.
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 "watchdog" timer. In case of a failure the
watchdog timer resets the microprocessor and gives
an alarm signal, via the output relay "self supervision".
I
I
=
>
1
I
I
2
%
Alarm
Tripping
Display
tI>
I>
I
tI>>
I>>
I
ϑ
ϑ
ϑ
tIE>
IE>
tIE>>
IE>>
Alarm
Trip
Relay 1
Relay 2
Relay 3
Relay 4
I> Tripping
I> Alarm
I>> Tripping
IE> Alarm
IE> Tripping
IE> Alarm
IE>> Tripping
IE>> Alarm
IL1
IL2
IL3
IE
Assignment
matrix
Blocking
matrix
Figure 4.1: Block diagram

10 TB MRI3-ITE(R) 12.00 E
4.3 Thermal replica
4.3.1 Definitions
Basic current IB:
Set limiting value of the overload current at which the
relay must not trip. This, in general, is the maximally
permissible operating current in consideration of addi-
tional influencing quantities on the heating (e.g. heat
dissipation by transformer oil or air convection).
The settings of the overload characteristics refer to this
basic current.
Time constant k:
Constant to be multiplied by the basic current in order
to determine the current that may be higher than IB.
Instruction for motor protection: k = 1...1.2
MRI3-ITE(R) default value: k = 0.5
Remark:
For the calculation of the temperature equivalent,
only the basic current has to be taken into account:
IB
2~ ϑ.
The constant k is used to determine the pickup value
(IB⋅k) and to calculate the temperature according to
which the object to be protected reaches its tripping
value after expiry of a long time (ϑTrip = k2⋅100%).
•Adjustment of the nominal current with IB(e.g. 1 ⋅IN)
and selection of an overload factor k (e.g. 1.2).
From this, a pickup value of 1.2 ⋅INand a tripping
value of 144% will result.
Thermal time constant τ:
It indicates the time until the temperature of the electri-
cal equipment to be protected reaches 63% of the sta-
tionary operating temperature. (data sheet of the elec-
trical equipment or practical values). Thumb rule: With
the current I being constant, approx. 63% of the
maximal temperature will be reached when t = τ. After
expiry of a time t = 5 ⋅τthe maximal temperature is
almost reached (99%).
The time constant for warming up and that for cooling
down may be different!
Tripping characteristic with preload:
Characteristic with complete memory function, taking
into account the thermal effect of the current before
occurence of the overload in the thermal replica of the
electrical item to be protected.
T(°C)/T
t
(
min
)
tau
100%
max
63%
T (k*I )
B
k^2 *
k^2 *
Figure 4.2: Thermal time constant τ