Seg HighTECH Line MRN3-3 User manual

MRN3-3
PROTECTION TECHNOLOGY
MADE SIMPLE
MAINS DECOUPLING RELAY WITH DF/DT AND
PROGRAMMABLE UNDERVOLTAGE CHARACTERISTICS
HighTECH Line
MAINS DECOUPLING RELAY WITH DF/DT
AND PROGRAMMABLE UNDERVOLTAGE CHARACTERISTICS
Original document
English
Revision: A
MANUAL

2 TD_MRN3-3_08.06_GB
Contents
1 Introduction and Application
2 Features and Characteristics
3 Design
3.1 Connections
3.1.1 Analogue input circuits
3.1.2 Blocking input
3.1.3 External reset input
3.1.4 Output relays
3.1.5 Fault recorder
3.2 Order of parameter settings
3.2.1 System parameters
3.2.2 Protection parameters
3.2.3 Parameter related to the fault recorder
3.3 LEDs
3.4 Front plate
4 Working Principle
4.1 Analogue circuits
4.2 Digital circuits
4.3 Voltage supervision
4.3.1 Selection of star or delta connection
4.4 Principle of frequency supervision
4.5 Measuring of frequency gradient
4.6 Vector surge supervision
4.7 Measuring principle of vector surge
supervision
4.7.1 Voltage threshold value for frequency-
df/dt measuring
4.8 Blocking function
5 Operation and Settings
5.1 Display
5.2 Setting procedure
5.3 System parameters
5.3.1 Display of measuring voltages U
E
as
primary quantity (U
prim
/U
sec
)
5.3.2 ∆/Y – Switch over
5.3.3 Setting of nominal frequency
5.3.4 Display of the activation storage
(FLSH/NOFL)
5.3.5 Parameter change-over switch/external
triggering of the fault recorder
5.4 Protection parameter
5.4.1 Setting parameters for under voltage
characteristics
5.4.2 SYMmetrical, ASYMmetrical or GENEral
faults*
5.4.3 Permissible release time for the under
voltage characteristic curve
5.4.4 Plausibility check of the voltage
characteristic
5.4.5 Parameter setting of the voltage functions
5.4.6 Number of measuring repetitions (T) for
frequency functions
5.4.7 Threshold of the frequency supervision
5.4.8 Tripping delays for the frequency
elements
5.4.9 Parameter setting of the vector surge
supervision or the frequency rate of
change df/dt
5.4.10 Voltage threshold value for frequency
and vector surge measuring (df/dt)
5.4.11 Adjustment of the slave address
5.4.12 Setting of Baud-rate (applies for Modbus
Protocol only)
5.4.13 Setting of parity (applies for Modbus
Protocol only)
5.5 Adjustment of the fault recorder
5.5.1 Number of the fault recordings
5.5.2 Adjustment of trigger occurences
5.5.3 Pre-trigger time (T
pre
)
5.6 Adjustment of the clock
5.7 Additional functions
5.7.1 Setting procedure for blocking of the
protection functions and assignment of
output relays
5.8 Indication of measuring and fault values
5.8.1 Measuring indication
5.8.2 Min./Max.- values
5.8.3 Unit of the measuring values displayed
5.8.4 Indication of fault data
5.9 Fault memory
5.9.1 Reset
5.9.2 Erasure of fault storage
5.9.3 Erasure of disturbance recorder

TD_MRN3-3_08.06_GB 3
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
6.5 Example of test circuit
6.5.1 Checking the input circuits and
measuring values
6.5.2 Checking the operating and resetting
values at over-/undervoltage
6.5.3 Checking the tripping delay of the
over-/undervoltage functions
6.5.4 Checking the operating and resetting
values of the over-/underfrequency
functions
6.5.5 Checking the tripping delay of the
over-/underfrequency functions
6.5.6 Checking the vector surge function
6.5.7 Checking the tripping and reset values of
the df/dt stages
6.5.8 Checking the external blocking and reset
functions
6.6 Primary injection test
6.7 Maintenance
7 Technical Data
7.1 Measuring input circuits
7.2 Common data
7.3 Setting ranges and steps
7.3.1 System parameter
7.3.2 Protection Parameter
7.3.3 Interface parameter
7.3.4 Parameters for the fault recorder
7.4 Output relays
8 Order form

4 TD_MRN3-3_08.06_GB
1 Introduction and Application
The mains decoupling relay MRN3-3 has been de-
signed for the use under special conditions, especially
to be found at wind parks.
If power generating systems are due to comply with
the GridCodes, i.e. if they shall not immediately dis-
connect from the grid in case of a mains failure, but
support it, instead, the MRN3-3 will be the optimal re-
lay. Its' function is to supervise mains voltage and
mains frequency in compliance with the GridCodes,
the grid connection rules and the operator guidelines.
For this reason, the distinction between short-distance
or long-distance errors is an elementary fact. As per
the requirements of the e-on grid connection rules (ver-
sion dd. 20.08.03) and the VDN guideline “EEG
power generating plants at high and maximum volt-
age systems”, in addition to the standard protection
functions, the MRN3-3 provides the voltage time
characteristics which are necessary to distinguish be-
tween short distance and long distance errors. Normal
voltage collapse shapes at mains failures are taken
into account by these characteristics, that allow selec-
tive disconnection of systems only there, where it is
absolutely required for operation.
If, in the event of a failure, the systems are to be con-
nected to the grid for a longer period, they will sup-
port the mains voltage and thus avoid large-area
breakdowns that could no more be compensated by
the interconnected network's primary control reserve.
Thanks to the presence of two independent character-
istics, it is possible to distinguish between short-term or
permanent interruption, each according to the type of
error.
In the event of a failure, the fault sequence can be re-
corded by an oscilloscope.
Within this error scenario, the MRN3-3 with its char-
acteristics hat have been applied for the first time in
protection technique - is of enormous use for the accu-
rate identification and analysis of the grid state - as
demanded by the rules.
General Note:
For further technical data and detailed descriptions,
please refer to our "MR - Digital Multifunctional Re-
lays".
2 Features and Characteristics
• Microprocessor technology with watchdog,
• effective analogue low pass filter for suppressing
harmonics when measuring frequency and vector
surge,
• digital filtering of the measured values by using dis-
crete Fourier analysis to suppress higher harmonics
and d.c. components induced by faults or system
operations,
• integrated functions for voltage, frequency and vec-
tor surge df/dt supervision in one device,
• two parameter sets,
• two free programmable under voltage limit curves
with each 5 definition points,
• three voltage supervision steps with under or over
voltage function that can be freely parameterised,
• frequency supervision with three step under-/or
over frequency function (user setting),
• completely independent time settings for voltage and
frequency supervision,
• adjustable voltage threshold value for blocking fre-
quency and vector surge measuring,
• display of all measuring values and setting parame-
ters for normal operation as well as tripping via a
alphanumerical display and LEDs,
• display of measuring values as primary quantities
• Storage of the pickup- and tripping values of three
failure events (voltage fail-safe),
• recording of up to four fault occurences with time
stamp
• to block the individual functions by the external
blocking input, parameters can be set according to
requirement,
• reliable vector surge measuring by exact calculation
algorithm,
• suppression of indication after an activation
(LED flash),
• Direct connection 690 V (linked).
• free assignment for output relays,
• display of date and time,
• in complience with VDE 0435, part 303 and
IEC 255,
• serial data exchange via RS485 interface possible;
alternatively with SEG RS485 Pro-Open Data Proto-
col or Modbus Protocol.

TD_MRN3-3_08.06_GB 5
3 Design
3.1 Connections
Figure 3.1: Connection diagram MRN3-3
3.1.1 Analogue input circuits
The analogue input voltages are galvanically decoup-
led by the input transformers of the device, then filtered
and finally fed to the analogue digital converter. The
measuring circuits can be applied in star or delta con-
nection (refer to chapter 4.3.1).
3.1.2 Blocking input
The blocking function can be set according to re-
quirement. By applying the auxiliary voltage to
D8/E8, the previously set relay functions are blocked
(refer to 4.8 and 5.7.1).
3.1.3 Reset input
Please refer to chapter 5.9.1.
3.1.4 Output relays
The MRN3-3 is equipped with 5 output relays. Apart
from the relay for self-supervision, all protective func-
tions 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: Signal self-supervision (internal failure of the
unit ) C7, D7, E7
All trip and alarm relays are working current relays,
the relay for self supervision is an idle current relay.

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3.1.5 Fault recorder
The MRN3-3 has a fault value recorder which records
the measured analogue values as instantaneous val-
ues.
The instantaneous values
U
L1
; U
L2
; U
L3
for star connection
or U
12
; U
23
; U
21
for delta connection
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 occurrences with a total
recording time of 18 s (with 50 Hz) and 15 s (with
60 Hz) per channel.
Storage division
Independent of the recording time, the entire storage
capacity can be divided into several of disturbance
events 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 re-
cordings in order to prevent that the stored data are
written over. After the data have been read and de-
leted, the recorder is 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.
Thus, the fault recorder can be adjusted to record the
following data/parameters:
Recorded length of time
Number of re-
corded faults 50 Hz 60Hz
1* 20 s 16.66 s
1 10 8.33 s
2* 10 s 8.33 s
3 5 s 4.16 s
4* 5 s 4.16 s
7 2.5 s 2.08 s
8* 2.5 s 2.08 s
When there is no more storage capacity left, the LED
FR starts flashing.
The memory part of the fault recorder is designed as
circulating storage. In this example 7 fault records can
be stored (written over).
Figure 3.2: Division of the memory into, for example, 8 segments
Memory space 6 to 4 is occupied.
Memory space 5 is currently being written in
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.
Figure 3.3: 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 (HTL/PL-Soft4). The data
is graphically edited and displayed. Binary tracks are
recorded as well, e.g. activation and trip.

TD_MRN3-3_08.06_GB 7
3.2 Order of parameter settings
3.2.1 System parameters
Setting parameter Unit Range
L1, L2, L3
Transmission ratio of the voltage transformers SEK, 1.01...6500
∆/Y
Input voltage correction depending on the input voltage
transformer connection
Y = star
DELT = Delta
fN
Adjustment of the rated frequency
Hz
50/60
∆Θ/df
Selection vector surge or df/dt function dPhi/dfdt
LED flashing after excitation
FLSH
FLSH/NOFL = flashing
NOFL = no flashing
P2
Parameter set change-over switch/Assignment of digital
inputs
Set1 = parameter set 1
Set2/2 = parameter set 2
FR = External triggering
B = External blocking
R = External Reset
SET 1
SET2
B_S2
R_S2
B_FR
R_FR
S2_FR
(refer to chapter 5.3.5)
3.2.2 Protection parameters
Setting parameters Unit Range
Char1+U<Start Start point of the limit curve 1 V 1–200/1–460/4–800*
Char1
Symmetrical, asymmetrical or general fault SYM; ASYM, ALL
Char1 Under voltage limit curve 1 warn = Display shows no „TRIP“
trip = Display shows „TRIP“
Char1+U<1 1. Char. point_value 1 (voltage value) V 1* - <= U<Start
2* - <= U<Start
Char1+U<1+t> 1. Char. point_value 2 (not parameterisable) s 0s fixed
Char1+U<2 2. Char. point_value 1 (voltage value) V >= U<1–200*/>=U<1–
460*/
>=U<1–800*
Char1+U<2+t> 2. Char. point_value 2 (time value) s > U<1+t> - 60s
Char1+U<3 3. Char. point_value 1 (voltage value) V >= U<2–200*/
>=U<2–460*/>=U<2–800*
Char1+U<3+t> 3. Char. point_value 2 (time value) s > U<2+t> - 60s
Char1+U<4 4. Char. point_value 1 (voltage value) V >= U<3–200*/
>=U<3–460*/>=U<3–800*
Char1+U<4+t> 4. Char. point_value 2 (time value) s > U<3+t> - 60s
Char1+U<5 5. Char. point_value 1 (voltage value) V >= U<4–200* and
>= U<Start–200*/
>= U<4–460* and
>= U<Start–460*/
>=U< 4–800* and
>= U<Start–800*
Char1+U<5+t> 5. Char. point_value 2 (time value) s > U<4+t> - 60s
Char1+tR Release time after voltage recovery 1 s 0.06 – 1.00s
Char2+U<Start Start point the limit curve 2 V 1–200/1–460/4–800*
Char2 Under voltage limit curve 2 warn = Display shows no „TRIP“
trip = Display shows „TRIP“
Char2
Symmetrical, asymmetrical or general fault SYM; ASYM, ALL
Char2+U<1 1. Char. point_value 1 (voltage value) V 1* - <= U<Start
2* - <= U<Start

8 TD_MRN3-3_08.06_GB
Setting parameters Unit Range
Char2+U<1+t> 1. Char. point_value 2 (not parameterisable) s 0s fixed
Char2+U<2 2. Char. point_value 1 (voltage value) V >= U<1–200*/
>=U<1–460*/>= U<1–800*
Char2+U<2+t> 2. Char. point_value 2 (time value) s > U<1+t> - 60s
Char2+U<3 3. Char. point_value 1 (voltage value) V >= U<2–200*/
>=U<2–460*/>= U2–800*
Char2+U<3+t> 3. Char. point_value 1 (time value) V > U<2+t> - 60
Char2+U<4 4. Char. point_value 1 (voltage value) V >= U<3–200*/
>=U<3–460*/>=U3–800
Char2+U<4+t>
4. Char. point_value 2 (time value)
s
> U<3+t> - 60s
Char2+U<5
5. Char. point_value 1 (voltage value)
V
>= U<4–200* and
>= U<Start–200*/
>= U<4–460* and
>= U<Start–460*/
>= U<4–800* and
>= U<Start–800*
Char2+U<5+t>
5. Char. point_value 2 (time value)
s
> U<4+t> - 60s
Char2+tR
Release time after voltage recovery 1
s
0.06 – 1.0
U1
Function of the 1st voltage element U< = undervoltage
U> = overvoltage
U1 Pick-up value for the 1st voltage element V 1–200/1–460/4–800*
tU1 (U1+t>) Tripping time for the 1st voltage element s 0,04 - 290
U2
Function of the 2nd voltage element U< = undervoltage
U> = overvoltage
U2 Pick-up value of the 2nd voltage element V 1–200/1–460/4–800*
tU2 (U2+t>) Tripping time of the 2nd voltage element s 0.04 - 290
U3
Function of the 3rd voltage element U< = undervoltage
U> = overvoltage
U3 Pick-up value of the 3rd voltage element V 1–200/1–460/4–800*
tU3 (U3+t>) Tripping time of the 3rd voltage element s 0,04 - 290
T Frequency measuring repetition in periods periods 2 - 99
f1Pickup value for frequency element 1 Hz 30–70 or 40–80
tf1 (f1+t>) Tripping delay of the 1st frequency element s tfmin. -290
f2pickup value for frequency element 2 Hz 30–70 or 40–80
tf2 (f2+t>) Tripping delay of the 2nd frequency element s tfmin -290
f3Pick-up value for frequency element 2 Hz 30–70 or 40–80
tf3 (f3+t>) Tripping delay of the 3rd frequency element s tfmin -290
∆Θ Pick-up value for the vector surge function 2–22
1-3 Vector surge tripping logic 1Pha/3Pha
df pickup value for rate of change of frequency (dt/dt) in Hz/s 0.2 - 10
dt measuring repetition for df/dt periods 2 - 64
UBvoltage threshold value for frequency and df/dt element V 5-100/12—230/20–400
RS Slave address of the serial interface 1 - 32
RS **Baud-Rate of the serial interface 1200 - 9600
RS **Parity check* even/odd/no
* Dependent on the rated voltage Un=100V/Un=230V/Un=400V/Un=690V
** Only at Modbus protocol

TD_MRN3-3_08.06_GB 9
3.2.3 Parameter related to the fault recorder
Setting parameter Unit Range
FR
Number of records 1 x 20/1 x 16.66*
1 x 10/1 x 8.33
2 x 10/2 x 8.33
3 x 5/3 x 4.11
4 x 5/4 x 4.11
7 x 2.5/7 x 2.04
8 x 2.5/8 x 2.04
FR
Storage of record, in case of event P_UP = with excitation
TRIP = with trip
A_PI = stop of all failures
TEST = test record
FR
Period before trigger event
s
0.05s – maximal recording time
*50Hz or 60Hz
Table 3.1: Parameter setting
3.3 LEDs
All LEDs (except LED FR, P2 and RS, min. and max.)
are two-coloured. The LEDs on the left side, next to the
alphanumerical display light up green during measur-
ing and red during fault message.
The LEDs below the push button <SELECT/RESET> are
lit green during setting and inquiry procedure of the
setting values which are printed on the left side next to
the LEDs. The LEDs will light up red after parameter-
rising of the setting values next to their right side.
The LED marked with letters RS lights up during setting
of the slave address of the device for serial data
communication.
The LED marked with the letters FR is alight while the
fault recorder is being adjusted.
3.4 Front plate
Figure 3.4: Front plate MRN3-3

10 TD_MRN3-3_08.06_GB
4 Working Principle
4.1 Analogue circuits
The input voltages are galvanically isolated by the in-
put transformers. The noise signals caused by inductive
and capacitive coupling are suppressed by an ana-
logue R-C filter circuit.
The analogue voltage signals are fed to the A/D-
converter of the microprocessor and transformed to
digital signals through Sample- and Hold- circuits. The
analogue signals are sampled with a sampling fre-
quency of 16 x f
N
, namely, a sampling rate of 1.25
ms for every measuring quantity, at 50 Hz.
4.2 Digital circuits
The essential part of the MRN3-3 relay is a powerful
microcontroller. All of the operations, from the ana-
logue 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 voltage in order to detect a possible fault situa-
tion in the protected object.
For the calculation of the voltage value an efficient
digital filter based on the Fourier Transformation (DFFT
- Discrete Fast Fourier Transformation) is applied to
suppress high frequency harmonics and d.c. compo-
nents caused by fault-induced transients or other system
disturbances. The microprocessor continuously com-
pares the measured values with the preset thresholds
stored in the parameter memory (EEPROM). If a fault
occurred an alarm is given and after the set tripping
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 Voltage supervision
The voltage supervision element of MRN3-3 is used to
protect generators, consumers and other electrical
equipment from over-/and undervoltage.
The relay is equipped with a 3-step voltage supervi-
sion unit with pre-selectable under- or over voltage
function and undervoltage (U<, U<<) function with
completely separate time and voltage settings.
In delta connection the phase-to-phase voltages and in
star connection the phase-to-neutral voltages are con-
tinuously compared with the preset thresholds.
For the overvoltage supervision the highest, for the un-
dervoltage supervision of the lowest voltage of the
three phases are decisive for energizing.