Seg MRD1-T User manual

MRD1-T -Transformer Differential Protection System

2TB MRD1-T 10.01 E
Contents
1 Preface and Application
2 Features and Benefits
3Design
3.1 Relay front
3.1.1 Display
3.1.2 LEDs
3.1.3 Push-buttons
3.1.4 Parameter interface RS232
3.2 Master module
3.2.1 Interface RS485
3.2.2 CAN-Bus (optionally)
3.2.3 Function inputs and signal inputs
(optionally)
3.3 Basic module and additional module
3.3.1 Basic module NT 6I (MRD1-G,
MRD1-T2 and MRD1-T3)
3.3.2 Additional module 3I (MRD1 T3)
4 Working principle
4.1 Protective functions
4.1.1 Transformer differential protection
4.2 Analogue measured value detection
4.2.1 Current measuring
4.3 Digital signal processor
4.4 Digital main processor
4.5 Block diagram
4.6 General functions
4.6.1 Event-Recorder
4.6.2 Fault-Recorder
4.6.3 Self-test relay
4.6.4 Self-test
4.6.5 Output relay settings
4.6.6 Parametrizing blocking
5Operation
5.1 General
5.1.1 Data organization
5.1.2 Parameter sets
5.1.3 Key function
5.1.4 LEDs
5.1.5 VIEW mode / EDIT mode
5.1.6 OFFLINE-TEST mode
5.1.7 Reset (DEVICE RESET)
5.1.8 Enter password
5.1.9 Password forgotten
5.2 SYSTEM settings
5.2.1 Selection
5.2.2 Overview
5.2.3 Time / Date
5.2.4 Password change
5.3 PARAMETER-pages
5.3.1 Selection
5.3.2 Overview
5.3.3 Transformer ratings
5.3.4 Protection parameters
5.3.5 Relay-settings
5.3.6 Setting of logic functions
5.3.7 Blocking Setting
5.3.8 Validity check
5.4 DATA pages
5.4.1 Selection
5.4.2 Overview
5.4.3 Measured and calculated data
5.4.4 FAULT Recorder
5.4.5 EVENT-Recorder
5.4.6 Statistic data
5.5 TEST-routines page (Self-test)
5.5.1 Page selection
5.5.2 Overview
5.6 Parameter programming help
6RelayTests
7 Commissioning
7.1 Check list
7.2 C.T. connection
8 Technical Data
8.1 MRD - Transformer Differential
Protection Relay
9 Tables / Connection diagrams
9.1 Possible event messages
9.2 View
10 Type code
This technical manual is valid for software version
V01-1.03.

TB MRD1-T 10.01 E 3
1Preface and Application
MRD1 is a modular system to protect electrical appa-
ratus and it is used for complex applications in the
energy distribution, primarily designed for transformer,
generator, motor or line protection; additionally it can
be integrated into automation systems. Due to its
modular design, the MRD1 can be adapted to indi-
vidual applications without problem, with all imple-
mented functions remaining combined in one single
device. All vacant rack places in the basic unit can op-
tionally be used for modules according to require-
ments. The modules provide the necessary measuring
inputs e.g. for two-winding or three-winding transform-
ers as well as increase the number of output relays or
digital inputs according to requirements.
The high-performance digital technique of data calcu-
lation makes complex mathematical algorithm for
measured value processing possible for the MRD1 as
well as utilization of the trip decision resulting from the
individual protection functions. The MRD1 software is
also of modular structure. Each protection function is al-
located to a special program segment and so it is
possible to subsequently add further functions.
All essential parameters, measuring data or values
calculated from these can be called off and are shown
locally on the display. The MRD1 is equipped with an
Event Recorder which stores all system signals, protec-
tion activations or trip events. When trips occur a Fault
Recorder records all fault data mesaured at the instant
of the trip. Data of both recorders is provided with a
time stamp and can be called off either at the display
or interface.
At present the following versions of MRD1 are avail-
able :
•MRD1-T2 Transformer differential protection for
two-winding transformers
•MRD1-T3 Transformer differential protection for
three-winding transformers
•MRD1-G Differential protection for generators and
motors

4TB MRD1-T 10.01 E
2Features and Benefits
Basic Unit
Standard equipment
•Modular design
with automatic short circuiting C.T.-inputs
•Signal and data processing in a separate digital
signal processor (32 samples per cycle)
•Digital filtering of measured quantities
•Three possibilities of parameter setting and data
calling:
1) keyboard and display
2) RS232 interface at the front (lap top)
3) RS485 interface for integration into control
systems at the rear
•Safety interlocking preventing parameter setting via
different ways at the same time
•extensive internal plausibility check of modified pa-
rameters
•Event Recorder for recording system messages
•Fault Recorder for recording measured fault data
•Four programmable independent parameter sets
•Non-volatile memory for parameter sets, events and
fault data
•Indication of measured operational values and re-
sulting quantities
•Wide-ranging automatic self-tests
•Small relay size
•Indication of relay functions optically or via sepa-
rate self supervision relay
•Three possibilities for relay resetting
•All data interfaces galvanical isolated
•Rated frequency selectable: 50 Hz/60 Hz
•Parameter setting protected by password
Functions which can be programmed by the user :
•Protection and system parameters
•Latched position or minimal signal duration for
each of the output relays
Optional equipment
•CAN Bus
•FO connection (fibre optic) for RS485 interface
•Addition of further protection functions after installa-
tion of additional software modules
Transformer differential protection
•Stabilization against transformer inrush and CT
saturation
•Adaption to vector groups and transformation ratio
by means of software without additional interpos-
ing CTs
•Compensation of tap changer position
•Waveform recognition technique with a special
Fourier algorithm (inrush element)
•No complete blocking of differential element but
only reduced sensivity
•Independent High Set differential element for heavy
faults

TB MRD1-T 10.01 E 5
3Design
This chapter informs briefly about operation elements
and indication elements of the MRD1. Name and po-
sition of the individual modules are also described. In
chapter 5 operating of the relay and type specific
functions are explained in more detail.
!Note
NoteNote
Note
Front view and rear view illustrations of the MRD1 as
well as connection diagrams can be found at the end
of the manual.
3.1 Relay front


Display in Home Position
3.1.1 Display
The MRD1 is provided with a 16-digit, double-line
liquid crystal display (LCD), which is of alphanumerical
design for an easy dialog. The figure above shows the
basic status of the display. Dependent on the mode se-
lected, the following data can be shown on the dis-
play:
•Date / Time / Relay type (Home Position)
•Measured operational data
•Measured fault data
•System parameters and protection parameters
•System signals and fault signals
3.1.2 LEDs
Additionally to the display there are max. 30 LEDs at
the front, indicating each of the operational status in
the MRD1. All LEDs are two-coloured (red/green) and
arranged in two groups:
a) System and relay status indications
The 15 system indications are arranged underneath
the alphanumerical display. They are allocated to a
certain function and show:
•Operational voltage available
•Trip
•OFFLINE TEST mode active
•Edit mode active
•Displayed parameter is modified but has not been
stored yet
•Switch status of the 5 (optionally 10) output relays
•Display of the relay function (self-test)
b) Status display of the 15 digital inputs (if provided)
These 15 indications are shown at the left of the dis-
play informing about the status of the digital inputs.
3.1.3 Push-buttons
All necessary MRD1 adjustments and inquiries can be
carried out from the front of the relay by pressing the
respective push-button (9 in total). Individual function of
these push-buttons is explained in chapter Operating.
3.1.4 Parameter interface RS232
At the left of the relay front there is a 9-pole, D-SUB
plug-and-socket connector for temporary lap-top con-
nection. At this connection a serial interface RS-232 is
provided. A standard IBMTM compatible PC or port-
able notebook can be connected to this PC interface.
To connected MRD1 and PC a 1:1 modem-cable with
9-pole plug-and-socket is used. By using SEG software
HTLSOFT 3, which is WindowsTM compatible, MRD1
parameters can comfortably be set. Additionally all
measured operational and fault data can be read out
of the relay integrated non-volatile memories.

6TB MRD1-T 10.01 E
3.2 Master module
The master module is fitted right in the middle and con-
tains componentries for data processing, the main
processor and the following connections:
3.2.1 Interface RS485
Interface RS485 at the rear of the relay is a permanent
connection between the MRD1 and the host computer.
This interface operates at a constant transmission ratio
of 9600 Baud if |SEG interface recorder "RS485pro"
is used. Via RS485 interface all measured operational
and fault data as well as operational status indications
can be read out - identical to RS232 interface. Remote
setting of parameters is also possible from the control
station. The 8-pole plug-and-socket connector contains
all necessary connections for this interface.
3.2.2 CAN-Bus (optionally)
This data interface is used for integrating the MRD1
into special automation systems and for specific func-
tion additions (e.g. temperature measuring module,
graphic-display module). For the CAN Bus interfaces
two 9-pole D-SUB plug-and-socket connectors are
used.
3.2.3 Function inputs and signal inputs
(optionally)
These 15 digital inputs (contacts 1-15) are combined
on the 16-pole plug-and-socket connector. The six-
teenth contact is the common return wire. Any incom-
ing information
a) can direct be assigned to selectable output relays.
This application method enables recording of the con-
tact status (open or closed) of external protection de-
vices (e.g. Buchholz relay at transformers)
b) can logically be interlinked with MRD1 internal pro-
tection functions. The logical interlinking result can than
be assigned to output relays.
An input can be considered active when a voltage
quantity within the permissible high range (see Tecni-
cal Data) is connected to the input contact and the
common return wire. If the voltage is lower, the input is
classed as being inactive. Specific function of the indi-
vidual inputs can be defined during programming (see
chapter 6). Digital inputs are galvanical isolated from
the relay electronics.

TB MRD1-T 10.01 E 7
3.3 Basic module and additional module
Plug-in units 1 and 3 are intended for individual appli-
cations and at our works they are equipped with mod-
ules for measuring value detection in compliance with
the relay function. (see folding page)
!Important Note
The MRD1 must only be dismantled or opened by authorized staff .
Removal of live modules entail severe danger for the person(s) involved because there can no sufficient protection
against accidental contact be guaranteed as soon as the relay has been opened. Furthermore there is the risk of
the modules being damaged by electrostatic discharge (ESD/EGB) when handled improperly.
Identical modules must not be exchanged between different MRD1 basic versions.
..
.
Calibration of every MRD1 is done at work with regard to the specific features of that relay. A random change
of modules would lead to unreliable operation of the relay because the compatibility of the relay components
among each other would be in disorder and could not be guaranteed any longer.
Any modification jobs on the MRD1, for instance, exchange of modules or software additions, are only allowed
to be done at our works or by authorized agents.
3.3.1 Basic module NT 6I (MRD1-G,
MRD1-T2 and MRD1-T3)
For generator, motor and transformer differential pro-
tection, module NT-61 is plugged into the first space.
Measuring inputs
The module consists of six current measuring channels
which are used for measuring the three conductor cur-
rents of each winding. The CT start point must be
formed outside the relay since all 12 CT connections
are wired separately on terminals. In addition to other
measuring or protection devices the MRD1 can be
looped in to existing CT lines, assumed the CT being
able to carry the total burden.
Apart from further connections for voltage supply of the
relay, the module is also provided with a digital input
for remote resetting as well as connection facilities for
the five output relays. Four of these are free to be used
acc. to requirement, the fifth is assigned for Selftest Re-
lay.
Input RESET
If a voltage is applied to terminals of the RESET input
(C8-D8), the MRD1 is reset to its basic status. By this
procedure possible alarms and trip signals are can-
celled.
The voltage applied for resetting must be within the
permissible high-range (see technical data), although it
must not necessarily be identical with the latter.
The input is galvanical isolated from the relay electron-
ics. Contact D8 is also the neutral or minus for the
blocking input.
Blocking Input
If a voltage is applied to the terminals of the blocking
input (D8-E8), all protection functions assigned to the
output relays are blocked. Terminal D8 is also the neu-
tral or minus for the reset input.
Alarm relays
Potential free outputs of the five alarm relays provided
are at terminals C, D and E, series 1 to 7. Exact allo-
cation can be taken from the connection diagram. Re-
lay 5 is permanently assigned to Selftest Relay. Func-
tion allocation of the remaining relays is free and can
be defined when programming (see chapter 5). Two
of these four relays are provided with two changeover
contacts each and the other two with one changeover
contact each.
3.3.2 Additional module 3I (MRD1 T3)
Module 3I is used for three-winding transformers and
applied to rack place 3. By this module the number of
measuring channels is increased by three currents for
the tertiary winding of the transformer and it provides
also five additional output relays.

8TB MRD1-T 10.01 E
4Working principle
In this chapter the individual functions and working
principle of the MRD1 are described.
4.1 Protective functions
4.1.1 Transformer differential protection
Term Explanation
ID Bias current This is the current flowing from the input side into the object to be protected, hav-
ing a respective output current available at the output side. This current is repre-
senting the normal load and the load at external faults.
Id Differential current The current resulting from the difference of incoming and outgoing conductor cur-
rents when these were converted at one transformer side.
In other words: The differential current is the component at the transformer input
current which has no related output current.
Ia Pickup current If the differential current exceeds the pickup current, the relay trips.
Fault current due to
operational condi-
tions
This kind of fault current is the component of the measured differential current
which, however, is not caused by a fault of the object to be protected but is of
systematic nature
Stabilization Under this heading all measures are compiled which stabilize the differential relay
against nuisance tripping. Stabilizing always means the pickup current is raised
and by this the differential relay becomes more intensitive, but is never completely
blocked.
ISStabilizing current This current develops from the bias current and represents the extent of stabilizing
measures necessary as result of the fundamental analysis. Parameters of the stabi-
lizing characteristic can be set.
mHarmonic stabilizing
factor
This factor, derived from the analysis of the harmonic frequency, is apart from IS
the second stabilizing factor and in case of rush and saturation by following a
special characteristic makes the differential relay stable against tripping errors.
d[Id] Characteristic Offset The characteristic curve is raised up by the value d[Id] immediately after a har-
monic stabilization factor “m” is measured to be greater than zero. This is to give
a basic stabilization after detection of inrush or ct-saturation during external fault
by means of harmonic measurement.
Pickup characteristic In this characteristic both stabilizing quantities (stabilizing current and stabilizing
factor) are brought together and from this the pickup current is defined necessary
for the operational condition of the object to be protected at that instant.
Table 1: Term definitions

TB MRD1-T 10.01 E 9
General idealized view
Differential protection is a strict selective object protec-
tion and is based on the current measuring principle at
the input and output side of the object being pro-
tected. Dependent on the earthing method used, the
neutral can also be included in measuring and bal-
ance.
The area between input and output CTs of the object
is classed as protection zone supervised by the
MRD1. Included in the protection zone are also CTs
and CT connection wire to the relay.
protected area
transformer
MRD
I
1
I
2
GRID GRID
Fig. 1: Definition of protection zone
The relay checks constantly if the incoming currents of
the input side are met by respective outgoing currents
at the output side. If the balance of the conductor cur-
rents shows a difference, this may suggest a fault
within the protection zone. Especially where trans-
formers are concerned it is necessary that all conductor
currents are converted to one reference transformer
side according to their transformation voltage ratio
and to their vector group so that quantities and phases
can be compared.
To distinguish between faults occuring within (inter-
nally) or outside (externally) of the protection zone is
the main purpose of the differential protection because
at internal faults the differential protection relay must
trip, but not so at external faults.
Examples:
External fault
During a short circuit occuring at the right grid, the
complete short circuit current flows through the trans-
former. The difference between incoming and outgo-
ing currents of all transformer terminals is small (in ideal
cases = zero) I1-I2= 0. The differential protection relay
does not trip. (Switching off in such cases probably to
be realized by an overcurrent relay).
protected area
transformer
MRD
I
1
I
2
short circuit current
GRID GRID
Fig. 2: External fault
Internal fault
When an internal fault occurs the current balance is
different. Dependent on the kind of fault a deficit in the
total of incoming currents can be observed. A winding
short circuit, for instance, can be fed from both sides,
even if with different intensity. But this short circuit does
not go through the transformer, it is fed from both grids
into the transformer. So therefore the current balance
shows a difference.
protected area
transformer
MRD
I
1
I
2
short circuit current
GRID GRID
Fig. 3: Internal fault (example of a short circuit fed from
two sides)
Due to the chosen direction of the reference arrow,
current I2flows here in negative direction.
The differential relays detects a current difference of I1-
I2= Id and trips when Id has exceeded the set thresh-
old.

10 TB MRD1-T 10.01 E
Stabilizing
At first approximation this idealized view applies to
stationary states only. In reality other effects, especially
dynamic processes, may cause the established current
difference to rise, even if there is no internal fault. In
such cases a simple static differential relay would mis-
takenly trip and to prevent this stabilizing measures
have to be taken. Possible sources of measuring errors
are systematic and can be duly taken into account.
Especial measures for detecting switching actions (in-
rush), CT saturation or to counteract errors caused by
transformer tap changer position switches are here ref-
ered to.
Stabilizing the MRD1 means always an action to
make the relay more insensitive. By the MRD1 two in-
dependent stabilizing quantities are calculated from
the fundamental oscillation and harmonic analysis (see
following paragraphs).
Fundamental analysis
Distortion factors for differential current measuring are:
•Measuring errors of angle and value of the CTs
used
•Poor adjustment of rated CT data to rated trans-
former data
•Effects caused by no-load currents
•Adverse effects caused by tap changer position
By these factors a fault current is caused which mainly
depends on the biasing current. This fault current is be-
ing measured as a differential current, although a
transformer fault must not necessarily have occured.
When the pickup current is set at a very sensitive
value, each of these static factors can cause unin-
tended trippings. With increasing bias current the
pickup current has to be corrected upwardly.
The following pickup characteristic (exact characteris-
tic) gives an detailed study of the individual fault fac-
tors and the resulting fault current. In fig. 4 the ex-
pected fault current versus tripping characteristic is
shown.
If a real fault occurs, the measured differential current
exceeds the biasing current caused by operational
conditions. Therefore the pickup characteristic must ex-
ceed the biasing current characteristic by the required
sensitivity value. The exact course can be approxi-
mated by a simplified characteristic consisting of two
linear sections (I and II). The higher the characteristic
begins, the higher the permissible differential current. If
the characteristic begins at a very low point this means
maximum sensitivity. If the pickup characteristic is be-
low the biasing characteristic, systematic effects can
cause unintended trips.
Stabilisierungsstrom
stabilizing current
Is / In
Differenzstrom
differential current
Id / In
I
II
AUSLÖSUNG
TRIP
KEINE AUSLÖSUNG
NO TRIP
tatsächlicher Fehlerstromlinie
exact fault characteristic
Angenäherte Kennlinie
approximated characteristic
Fig. 4: Typical pickup characteristic (without considering transient processes)
Calculation of the differential current and stabilizing current resulting from the fundamental oscillation of the input
and output currents (current of the negative and positive phase sequence system) produces a point on the charac-
teristic. If this point is within the tripping range, the output relay picks up.

TB MRD1-T 10.01 E 11
Harmonic analysis
The analysis of harmonics allows detection of special
processes in the grid, which also distort ascertainted
differential current values.
These factors are:
•Inrushes
•Overexcitation of the transformer by overvoltage or
underfrequency
•CT saturation at very high current load caused by:
- severe faults (external short circuit at high load)
- start-up phases of big motor-operated drives
- magnetizing currents of unloaded transformers
- faults within the zone to be protected
(short circuits)
We will explain the harmonic oscillation analysis more
detailed by taking the example "CT saturation" :
In unstabilized transformer differential protection sys-
tems instabilities can arise which may have grave con-
sequences because the CT core is saturated due to
transient processes. In this state the CTs, arranged at
either side of the zone to be protected, do not portray
the "right" secondary current (when compared to the
primary side). Through this constallation the differential
protection relay detects at the secondary side of the
CTs a differential current Id' which does, however, not
exist at the primary side and this may cause unin-
tended tripping.
In fig. 5 core saturation due to short circuit current is il-
lustrated.
Short circuit currents often contain a DC component.
The high primary current arising during this kind of fault
generates a magnetic B induction, causing saturation
of the iron core.
The iron core keeps this high induction until the primary
current has reached zero. During the time the core is
saturated, the secondary current is not in compliance
with the primary current, but becomes zero. During the
time the core is not saturated, the CT induces a current
which does not represent the real current for the entire
cycle duration, its effective value is far too low.
Fig. 5 Core saturation of a CT
a) primary current with DC component
b) induction in the core
c) secondary current
Different saturation of CTs belonging to one protection
zone generate differential current Id' causing some un-
stabilized relay to trip.
For the harmonic analysis the MRD1 exploits the
second, fourth and fith harmonic.
Important Note.
For perfect functioning of the rush stabilization system it
is essential that the MRD-T is connected in the correct
phase sequence, i.e. that there is a positive rotating
field. Refer also to page 11.

12 TB MRD1-T 10.01 E
Trip characteristic
The MRD1 identifies such factors by using the har-
monic analysis and calculates a second dynamic stabi-
lizing quantity, i.e. stabilzing factor m. Harmonic
analysis makes also detection of an inrush and trans-
former saturation caused by overvoltage possible and
are added to the calculation of the stabilizing factor.
The MRD1 ascertains stabilizing factor m for the
present situation with the effect of further lifting the
complete characteristic. Calculation of m is defined
and cannot be adjusted.
m and ISeach stabilize the relay entirely separate from
each other, but never have a complete blocking effect.
Both stabilizing quantities together define the pickup
value in the trip characteristic.
A basic stabilization is performed by the parameter
d[Id]. For all cases m>0 (rush current, single sided ct-
saturation and external faults) the characteristic curve is
raised up for the minimum amount of d(Id). Another
additional raising is performed for raising m (more
servere rush, more severe ct-saturation).
The additionally adjustable parameter Idiff high set
(Idiff >>) is a high current differential element. This set-
ting value is not subjected to stabilization and specifies
the highest permissible differential current. This pa-
rameter defines characteristic sector III.
Tripping procedure
The protection program permanently checks the meas-
urements that the DSP (digital signal processor) deliv-
ers. When the DSP gives a new differential current the
protection task checks whether it lies within the tripping
limits. If this is the case the MRD1 is internally ener-
gized. Tripping occurs when the calculated difference
current is consecutively three times within the tripping
limits. To prevent the energized state from being reset
too quickly, a hysteresis of 75 % is programmed. This
means that a newly calculated difference current must
be smaller than 75 % of the present characteristic trip
value in order for the energized condition to be reset.
The total tripping time of the Relay is below 35 ms.
0
Stabilisierungstrom
stabilizing current
Is / In
Differenzstrom
differential current
Id / In
I
II
III
AUSLÖSUNG
TRIP
KEINE AUSLÖSUNG
NO TRIP
m
Idiff >>
(Für interne Fehler)
(for internal faults)
d[Id]
Fig. 6: Dynamic stabilized trip characteristic (pick-up value).

TB MRD1-T 10.01 E 13
4.2 Analogue measured value detection
4.2.1 Current measuring
For measuring the relevant currents there is a separate
transducer for each of the existing measured quantities.
This transducer provides galvanical isolation to the re-
lay electronics. Adjustment to transformer vector group
and to the main CT rated currents is realized via the
software. The input signal is transmitted by internal CTs
up to 64 times rated current linear. To achieve an ut-
most accuracy there are two current measuring ranges,
changeover of which is automatically.
Each channel has its own sample-and-hold circuit. All
channels are scanned simultaneously.
4.3 Digital signal processor
The digital signal processor (DSP) in the MRD1 is
mainly used for processing measured values by con-
trolling and monitoring data entry from the different
measuring channels. In addition all input signals are
digitally Fourier filtered. Among other values this proc-
essor calculates RMS values and analyzes harmonics
by processing sampled data and stores digitalized
signal sequences to the memory. Apart from data
management and processing the DSP keeps perform-
ing wide-ranging self-tests.
4.4 Digital main processor
The main processors is the highest control element
within the MRD1 and processes the actual protection
program which interprets data obtained by the DSP
and so refers to the operational status of the object to
be protected and to the own device. Special protec-
tion mechanism enable the MRD1 to detect problems
in the own hardware. All communication between
MRD1 and the outside world is also controlled by the
main processor. This does not only mean control of in-
dications or handling of key inputs but also harmoniz-
ing the different data interfaces as well as control of
output relays.

14 TB MRD1-T 10.01 E
4.5 Block diagram
∩
∩∩
∩
∩
∩∩
∩
RS
485
serial
ports
display and keyboard
CTs
real time
clock
CAN
Bus1
CAN
Bus2
LWL
CAN-
con-
tro-
ller
fault
memory
program
memory
3
3
3
∩
∩∩
∩
analogue measurements
PCM
memory card
serial PC-interface
RS232
signal-
processor
main
processor
central module
extension module
base module
main processor bus
optional
communi-
cation
parameter-
memory
blocking
input
supply
5
output
relays
SOFTWARE
Relay
matrix
∩
∩∩ ∩
#
## #
RESET
input
dual ported
memory
5
output
relays

TB MRD1-T 10.01 E 15
4.6 General functions
4.6.1 Event-Recorder
The MRD1 is provided with an event recorder for re-
cording events in a chronological order and then
stores them on a non-volatile memory. Any data entry
has a time stamp so that time of the event can al-
ways be traced back. Data can be called off either
via keys and display or data interfaces.
Important events, such as trippings, are not only re-
corded in the memory but also shown on the display.
Pure informative events are stored in the recorder
only and are not displayed.
More details on calling off events and further infor-
mation on the event recorder can be found in chap-
ter 5.
The system messages are listed in chapter 9.1.
4.6.2 Fault-Recorder
At each tripping of the relays, the fault recorder rec-
ords all measured data and resulting quantities. Any
tripping event is automatically numbered consecu-
tively in the recorder. Additionally to the measured
data the following details are also stored: the cause
for tripping, serial number of the incident as well as
date and time at the instant of tripping.
The MRD1 is able to record several incidents in a
FIFO memory. The longest stored data is overwritten
when a new incident occurs. Complete data of alto-
gether 10 incidents can always be called off.
More information on storage capacity and calling off
recorder data via keyboard can be found in chapter 5.
4.6.3 Self-test relay
The self-test relay (relay 5) is energized during nor-
mal operation of the MRD1 and deenergized in the
following events:
•failure of aux. voltage
•failure of internal partial power supply
•processor failure detected by the internal watch-
dog
•detection of an internal fault by software routines
•when protection function of the output relays is
decoupled in OFFLINE TEST mode
•when the default parameterset was loaded and
the device automatically switched in OFFLINE
TEST mode
•During power on initialisation
•self-test of the output relays is performed

16 TB MRD1-T 10.01 E
4.6.4 Self-test
By pressing the TEST key several menu guided spe-
cial test routines can be started in the MRD1 for in-
ternal test purposes. Some tests disable the trans-
former protection. These tests are locked by pass-
word.
The following tests and information can be per-
formed/is available :
Test / Inquiry Description Password
re-
quested
Protection
function
Software version number Number of version and date of software are in-
quired no remains active
LED-Test •all LEDs light-up red f. 2s
•all LEDs light up green f.2s no remains active
Test of output relays Sequence in one-second interval:
•self-test relay de-energizes
•all other relays de-energize
•all relays energize one after the other (with LED)
•relays return to actual position
•self-test relay energizes
yes inactive during the
test
Memory test Test of software and memory by checking the pro-
gram check sum no remains active

TB MRD1-T 10.01 E 17
4.6.5 Output relay settings
Reset time of the output relays:
With the exception of the self-supvervision relay, all
existing output relays are assigned to the differential
current element. It is possible to define a proper reset
time for each individual relay. For this period - from
the moment of tripping - the relay remains in trip
condition even if the cause for the tripping does no
more exist.
!Note:
If the time for which the relay has been energized
exceeds the adjusted reset time, the relay will release
instantaneously after trip condition is canceld. This is
particularly important for relay tests (test of the reset
time) where the test current is not switched off imme-
diately with tripping.
TRIP condition
Auslösebedingung
Relay energized
Relais angezogen
RESET TIME
Mindestkommandozeit
t
RESET TIME
Mindestkommandozeit
1
0
1
0
Fig.: Reset time
If a relay is to remain self-holding after tripping, the
reset time has to be set to „exit“. Setting as per cus-
tomer’s requirements can be noted down in the „se-
lection“line.
Relay
Basic equipment Option
12345678910
Function Idiff
Idiff >>
Idiff
Idiff >>
Idiff
Idiff >>
Idiff
Idiff >> ST Idiff Idiff >>
Idiff
Idiff >>
Idiff
Idiff >>
Idiff
Idiff >>
Idiff
Idiff >>
Pre-adjustment
(in s) 0,20 0,20 0,20 0,20 •0,20 0,20 0,20 0,20 0,20
Custom •
Setting range: 0 -...1,00 s or exit (=latching- contact un-
til a DEVICE RESET is performed)
ST=Self-Test relay
•= no selection

18 TB MRD1-T 10.01 E
4.6.6 Parametrizing blocking
Blocking of protective function
The MRD1 offers a configurable blocking function.
When applying a voltage to terminals D8-E8 all protec-
tive functions are blocked that are configured for block-
ing. In case of active blocking the output relays don’t
act, but the device shows the fictive trip by means of
Trip-LED.
A minimum hold time can be set for the blocking. During
this time, starting from the begin of external blocking, all
protective functions are blocked, also in case the exter-
nal blocking may was released. In case of longer con-
tinuous external blocking the blocking can be stopped
after a maximum hold time tmax for enabling the relay to
trip in case of ongoing faults.
wirksame Blockierzeit
effective block. time
ext. Block. Eingang
ext. blockage input
t
min
t
t
max
!Note:
Repeated impulse at the blocking time within tmin restart
the hold times.
Assignment of functions to output relays
The MRD1 offers 5 output relays. Relay number 5 is
preassigned to the selftest function of the relay and is
working with zero-signal current principle. Output relays
1 –4, and 6 –10 are open-circuit relays and can be
assigned to internal logic functions.

TB MRD1-T 10.01 E 19
5Operation
5.1 General
5.1.1 Data organization
Data and settings in the MRD1 are subdivided into 4
groups and each of those are allocated to one menu
key or key combination. Related parameters or measur-
ing data of one group are combined on individual
pages. General settings can be made on the SYSTEM
parameter page. Test routines are also on separate
pages.
EVENT
Recorder
PARAMETER
measurements
data recorder
PARAMETER
page 3
parameter 3.1
parameter 3.2
parameter 3.3
...
...
...
...
PARAMETER
page 2
parameter 2.1
parameter 2.2
parameter 2.3
...
...
...
...
PARAMETER
page 1
parameter 1.1
parameter 1.2
parameter 1.3
...
TEST-
routines
TEST
routines
software version
relays test
LED test
memory test
4 parameter sets
SYSTEM-
parameter
SYSTEM
PARAMETER
clock setting
serial port options
work set selection
OFFLINE TEST m.
change password
restore default
rated frequency
FAULT
Recorder
...
...
...
+
DATA
page 1
measurement1.1
measurement 2.2
measurement 3.3
...
Statistic Data
Fig. 5.1: Data organization

20 TB MRD1-T 10.01 E
5.1.2 Parameter sets
MRD1 has access to four independent parameter
sets. Each of these data sets comprises a complete
parameter set which makes individual setting of the
MRD1 possible. If required by the operational pro-
cedure several different settings can be stored and
then called off when needed.
Data of SYSTEM parameters (e.g. rated frequency,
slave address, date, time etc.) are not filled in the
four parameter sets, they do always apply.
EDIT-
memory
display / keyboard
serial interface


parameter set
1
parameter set
2
parameter set
3
parameter set
4
protection-
program
output
relay
message
display / LED
measurement
switch open in
Offline Test Mode
SYSTEM-
parameter
transformer
Fig. 5.1.2: Parameter sets, principle
For processing the selected set is loaded into the
EDIT memory (switch: Set to Edit). After parameters
have been changed, the EDIT memory is completely
restored in the parameter set memory. All changes
are then jointly read-in.
Another switch (Work Set) defines on which of the
data sets the protection program is based. All
switches are adjusted via software.
OFFLINE TEST mode is specified in chapter 5.1.6.