Seg HighTECH MRU3-2 User manual

MRU3-2
PROTECTION TECHNOLOGY
MADE SIMPLE
VOLTAGE RELAY WITH EVALUATION OF
SYMMETRICAL COMPONENTS
HighTECH Line
VOLTAGE RELAY WITH EVALUATION OF SYMMETRICAL COMPONENTS
Revision: B
Original document
English
MANUAL

SEG Electronics GmbH Manual MRU3-2
2 DOK-TD-MRU3-2, Rev. B
SEG Electronics reserves the right to update any portion of this publication at any time.
Information provided by SEG Electronics is believed to be correct and reliable.
However, no responsibility is assumed by SEG Electronics unless otherwise expressly undertaken.
© SEG Electronics 1994–2020. All rights reserved.

Manual MRU3-2 SEG Electronics GmbH
DOK-TD-MRU3-2, Rev. B 3
Contents
1. Introduction and application.......................................................................5
2. Features and characteristics ......................................................................5
3. Design...........................................................................................................6
3.1 Connections ........................................................................................................................6
3.1.1 Analog input circuits........................................................................................................7
3.1.2 Blocking input..................................................................................................................7
3.1.3 External reset input .........................................................................................................7
3.1.4 Output relays...................................................................................................................7
3.1.5 Fault recorder..................................................................................................................8
3.1.6 Parameter settings..........................................................................................................9
3.2 Display...............................................................................................................................10
3.3 LEDs..................................................................................................................................10
3.4 Front plate.........................................................................................................................11
4. Working principle.......................................................................................12
4.1 Analog circuits...................................................................................................................12
4.2 Digital circuits....................................................................................................................12
4.3 Selection of star or delta connection.................................................................................13
4.4 Voltage supervision...........................................................................................................14
4.4.1 1-phase/3-phase supervision........................................................................................14
4.4.2 Principle of the voltage unbalance protection ...............................................................14
4.4.3 Measuring principle.......................................................................................................15
4.4.4 Negative sequence system of a symmetrical voltage system ......................................16
4.4.5 System with voltage unbalance.....................................................................................16
4.4.6 Zero sequence system..................................................................................................17
5. Operations and settings............................................................................18
5.1 Display...............................................................................................................................18
5.2 Setting procedure..............................................................................................................19
5.3 System parameter.............................................................................................................20
5.3.1 Display of residual voltage UE as primary quantity (Uprim/Usec).....................................20
5.3.2 D/Y –Switch - over........................................................................................................20
5.3.3 Setting of nominal voltage.............................................................................................20
5.3.4 Display of the activation storage...................................................................................21
5.3.5 Parameter set change-over switch/external trigger for fault recorder...........................21
5.4 Protection parameters.......................................................................................................22
5.4.1 1-phase or 3-phase U</U>-tripping...............................................................................22
5.4.2 Parameter setting of over- and under voltage supervision ...........................................22
5.4.3 Positive sequence system voltage (U1<, U1>).............................................................22
5.4.4 Negative sequence system overvoltage (U2>).............................................................22
5.4.5 Zero sequence system overvoltage (U0>)....................................................................22
5.4.6 Adjustment of the slave address...................................................................................22
5.4.7 Setting of Baud-rate (applies for Modbus-Protocol only)..............................................23
5.4.8 Setting of parity (applies for Modbus-Protocol only).....................................................23
5.5 Parameter for the fault recorder........................................................................................23
5.5.1 Adjustment of the fault recorder....................................................................................23
5.5.2 Number of the fault recordings......................................................................................23
5.5.3 Adjustment of trigger occurrences ................................................................................23
5.5.4 Pre-trigger time (Tvor)...................................................................................................23
5.6 Date and time....................................................................................................................24
5.6.1 Adjustment of the clock.................................................................................................24
5.7 Indication of measuring values..........................................................................................25
5.7.1 Measuring indication .....................................................................................................25
5.7.2 Unit of the measuring values displayed ........................................................................25
5.7.3 Indication in faultless condition .....................................................................................25
5.7.4 Indication after pickup / tripping ....................................................................................25
5.7.5 Indication of the phase sequence .................................................................................26
5.8 Fault memory ....................................................................................................................26
5.9 Additional Funktion............................................................................................................27

SEG Electronics GmbH Manual MRU3-2
4 DOK-TD-MRU3-2, Rev. B
5.9.1Setting procedure for blocking the protection functions ...............................................27
5.9.2 Reset.............................................................................................................................28
5.9.3 Erasure of fault storage ................................................................................................29
6. Relay testing and commissioning............................................................30
6.1 Power-On..........................................................................................................................30
6.2 Testing the output relays ..................................................................................................30
6.3 Checking the set values....................................................................................................31
6.4 Secondary injection test....................................................................................................32
6.4.1 Test equipment.............................................................................................................32
6.4.2 Example of the test circuit.............................................................................................32
6.4.3 Checking the input circuits and measuring functions ...................................................33
6.4.4 Test of the symmetrical components values ................................................................34
6.4.5 Checking the operating and resetting values of the over/under voltage functions.......36
6.4.6 Checking the relay operating time of the over/under voltage functions .......................36
6.4.7 Checking the external blocking and reset functions.....................................................36
6.5 Primary test.......................................................................................................................37
6.6 Maintenance .....................................................................................................................37
7. Technical Data............................................................................................38
7.1 Measuring input circuits....................................................................................................38
7.2 Common data ...................................................................................................................38
7.3 Setting ranges and steps..................................................................................................39
7.3.1 Interface parameter ......................................................................................................39
7.3.2 Parameter for the fault recorder....................................................................................40
7.4 Output relays ....................................................................................................................40
8. Order form..................................................................................................41

Manual MRU3-2 SEG Electronics GmbH
DOK-TD-MRU3-2, Rev. B 5
1.Introduction and application
The MRU3-2 is a relay for voltage supervision with universal application, it protects the three-phase
network against voltage unbalance or earth faults in isolated networks. Beside the pure rms value
measurement of the line voltage the MRU3-2 evaluates the symmetrical components (positive-,
negative- and zero sequence system). By evaluating these components relay MRU3-2 can detect
the phase sequence, voltage unbalance and earth-faults.
Important:
For additional common data of all MR-relays please refer to technical description "MR - Digital Mul-
tifunctional Relays".
2.Features and characteristics
Microprocessor technology with watchdog,
digital filtering of the measured values by using discrete Fourier analysis to suppress
higher harmonics and d.c. components induced by faults or system operations,
analog low pass filter,
two parameter sets,
voltage supervision each with two step under-/ and overvoltage detection,
voltage supervision for each phase separately
completely independent time settings for voltage supervision
separate tripping elements for over- and under-voltage and positive sequence system
overvoltage detection in negative- and zero sequence system,
display of measuring values of the line voltages and system voltages U0, U1 and U2 as
rms values (zero , positive- and negative sequence system)
alternatively connection and measurement of the phase-to-neutral or phase-to-phase
voltage
display of the phase sequence,
display of all measuring values and setting parameters for normal operation as well as
tripping via a alphanumerical display and LEDs,
display of measuring values as primary quantities,
tripping memory for all line voltages and the voltages of the symmetrical components,
storage and display of tripping values in a fault memory (voltage-failure safe),
recording of up to eight fault occurrences with time stamp
for blocking the individual functions by the external blocking input, parameters can be set
according to requirement,
suppression of indication after an activation (LED flash),
free assignment for output relays,
display of date and time,
in compliance with VDE 0435, part 303 and IEC 255,
mains frequency is adjustable to 50 Hz or 60 Hz or variable from 40 - 70 Hz,
RS485 interface for communication with master systems
serial data exchange via RS485 interface possible; alternatively with RS485
ProOpen Data Protocol or Modbus Protocol.

SEG Electronics GmbH Manual MRU3-2
6 DOK-TD-MRU3-2, Rev. B
3.Design
3.1 Connections
Figure 3.1: Star connection of the voltage transformers
Figure 3.2: Delta connection of the voltage transformers
Attention!
If the input transformers are connected in delta circuit no detection of zero phase sequence (U0) is
possible.

Manual MRU3-2 SEG Electronics GmbH
DOK-TD-MRU3-2, Rev. B 7
3.1.1 Analog input circuits
The analog input voltages are galvanic ally decoupled by the input transformers of the device, then
filtered and finally fed to the analog digital converter. Depending upon the demands the MRU3-2
can be connected directly to the mains or via external voltage transformers in star- or delta connec-
tion. The priority should be given to the star connection, because of the ability to detect a zero se-
quence system.
3.1.2 Blocking input
When the voltage, which must be in the admissible range of the auxiliary voltage, is connected to
terminals D8/E8, the following tripping functions are blocked undelayed:
Under voltage U</U<<
Over voltage U>/U>>
positive sequence system undervoltage U1<
positive sequence system overvoltage U1>
negative sequence system overvoltage U2>
zero sequence system overvoltage U0>
Blocking can be freely selected via the allocation mode. (refer to chapter 5.9).
Input D8 is the ground (L- or N) for blocking and the external reset. The blocked functions are again
released undelayed when the auxiliary voltage is disconnected from the terminals D8/E8.
The above mentioned functions remain blocked for 2 s after the supply voltage had been applied.
3.1.3 External reset input
Refer to chapter 5.9.2
3.1.4 Output relays
The MRU3-2 is equipped with 5 output relays.
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.

SEG Electronics GmbH Manual MRU3-2
8 DOK-TD-MRU3-2, Rev. B
3.1.5 Fault recorder
The MRU3-2 has a fault value recorder which re-cords the measured analog values as instantane-
ous values.
The instantaneous values
UL1; UL2; UL3 for star connection orU12; U23; U31 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.
Storage division
Independent of the recording time, the entire storage capacity can be divided into several cases of
disturbance with a shorter recording time each. In addition, the deletion behavior of the fault
recorder can be influenced.
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 recordings 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 number of partial segments is reserved in the com-
plete 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 re-
cords can be stored (written over).
Memory space 6 to 4 is occupied.
Memory space 5 is currently being written in
Figure 3.3: Division of the memory into 8 segments, for example

Manual MRU3-2 SEG Electronics GmbH
DOK-TD-MRU3-2, Rev. B 9
Since memory spaces 6, 7 and 8 are occupied, this example shows that the memory has been as-
signed more than eight recordings. This means that No. 6 is the oldest fault recording and No. 4
the most recent one.
Figure 3.4: 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.
3.1.6 Parameter settings
System parameters
Uprim/Usek Primary/secondary measured value display of the voltage tranfor
mers
D/Y Selection of switching groups
fNRated frequency
LED-Flash Suppression of LED flashing after activation
P2/FR Parameter switch/external trigger for the fault recorder
Protection parameters
1/3 1-phase or 3-phase U</U> tripping
U< Pickup value for under voltage
tU< Trip value for under voltage low set element
U<< Pickup value for under voltage
tU<< Trip value for under voltage high set element
U> Pickup value for overvoltage
tU> Trip value for overvoltage low set element
U>> Pickup value for overvoltage
tU>> Trip value for overvoltage high set element
U1< Pick-up value for under voltage in positive-phase sequence system
tU1< Trip value for under voltage in positive phase sequence system
U1> Pick-up value for overvoltage in positive phase sequence system
tU1> Trip value for overvoltage in positive phase sequence system
U2> Pick-up value for overvoltage in negative phase sequence system
tU2> Trip value for overvoltage in negative phase sequence system
U0> Pick-up value for overvoltage in zero phase sequence system
tU0> Trip value for overvoltage in zero-phase sequence system

SEG Electronics GmbH Manual MRU3-2
10 DOK-TD-MRU3-2, Rev. B
Parameters for the fault recorder
FR Number of disturbance events
FR Trigger events
FR Pre-trigger time Tvor
Date and time
Year Y = 00
Month M = 04
Day D = 18
Hour h = 07
Minute m = 59
Second s = 23
Additional functions
Blocking function
Relay configuration
Fault memory
3.2 Display
The display is used for indicating all setting- and measuring values. The actual measuring values
as also the fault values can be indicated. In faultless operation the indicated value of the normal
operation can be called by pressing the <SELECT> and <ENTER> pushbuttons.
After tripping the display changes into the tripping mode from where fault data can be called.
3.3 LEDs
LEDs L1, L2, L3, U1 and U2 left from the display are two-colored and indicate the measured quan-
tities; green for measuring values and red for fault indication.
LED U0 lights yellow which normally indicates (relay not tripped) that the measuring value of the
zero sequence system and in case of tripping the tripping value of the zero sequence system is
shown in the display.
The LED marked with the letters RS lights up during setting of the slave address for the serial inter-
face (RS 485) of the unit.
The LED marked with "FR" lights up during parameter setting at the fault recorder. When LED •
lights up, date and time are displayed. LED "PS" indicates the phase sequence.
The 9 LEDs below the <SELECT/RESET> pushbutton signalize the parameter of the individual
tripping elements. In case of tripping they indicate, together with the upper LEDs, the respective
kind of fault.
A permanent red light indicates tripping. When the tripping delay has not elapsed the LEDs of the
corresponding combination (at pickup) are flashing.
If one of the limit values is exceeded for only a short time before the set tripping delay is not ex-
pired, the corresponding LED combination flashes. This flashing is shorter than for warning. This
pickup warning signal can be switched off with a reset. This activation signal can be shut-down with
the "Reset" key (refer to chapter 5.9.2) or suppressed by the FLASH/NO_FLASH function. The ac-
tive parameter set is indicated by LED "P2". LED D/Y lights up during parameter setting for the in-
terlinking of the input voltage CTs.