Seg HighTECH MRG3 User manual

MRG3
PROTECTION TECHNOLOGY
MADE SIMPLE
GENERATOR PROTECTION WITH MAINS
SUPERVISION, TIME OVERCURRENT PROTECTION
AND EARTH CURRENT SUPERVISION
HighTECH Line
GENERATOR PROTECT
GENERATOR PROTECTION WITH MAINS SUPERVISION,
TIME OVERCURRENT PROTECTION AND EARTH CURRENT SUPERVISION
Original document
English
Revision: D
MANUAL

SEG Electronics GmbH Manual MRG3
2 DOK-TD-MRG3, Rev. D
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 MRG3 SEG Electronics GmbH
DOK-TD-MRG3, Rev. D 3
Inhalt
1. Overview and Application...........................................................................6
2. Features and Characteristics......................................................................7
3. Design...........................................................................................................8
3.1 Connections ........................................................................................................................8
3.1.1 Connection Diagrams......................................................................................................8
3.1.2 Analog input circuits......................................................................................................13
3.1.3 Output relays.................................................................................................................13
3.1.4 Blocking input................................................................................................................13
3.1.5 External reset input .......................................................................................................13
3.1.6 Serial interface ..............................................................................................................13
3.1.7 Auxiliary voltage supply.................................................................................................13
3.1.8 Code plugs....................................................................................................................14
3.1.9 Low/high range of the digital inputs...............................................................................16
3.2 Front plates .......................................................................................................................17
3.3 LEDs..................................................................................................................................20
4. Working Principle ......................................................................................21
4.1 Analog circuits...................................................................................................................21
4.2 Digital circuits....................................................................................................................21
4.3 Voltage supervision...........................................................................................................21
4.3.1 Selection of star or delta connection.............................................................................22
4.4 Principle of frequency supervision ....................................................................................23
4.5 Mains decoupling ..............................................................................................................24
4.5.1 Measuring of frequency gradients.................................................................................24
4.5.2 Vector surge supervision...............................................................................................25
4.5.3 Measuring principle of vector surge supervision...........................................................26
4.5.4 Voltage threshold value for frequency, df/dt and vector surge measuring ..................29
4.6 Over current- and short circuit supervision .......................................................................29
4.7 Earth fault protection.........................................................................................................30
4.7.1 Generator stator earth fault protection..........................................................................30
4.7.2 System earth fault protection ........................................................................................30
4.7.3 Earth-fault directional feature........................................................................................31
4.7.4 Residual voltage............................................................................................................33
4.7.5 Behavior of MRG3 under different operating conditions...............................................33
4.7.6 Blocking function set in compliance with requirements.................................................33
4.8 Fault recorder....................................................................................................................34
5. Operation and Settings..............................................................................36
5.1 Display...............................................................................................................................36
5.2 Setting procedure..............................................................................................................40
5.3 Systemparameters............................................................................................................40
5.3.1 Y –Change-over switch................................................................................................40
5.3.2 Display of measurement values as primary quantity ....................................................40
5.3.3 Setting of measured secondary values for the voltage transformers............................40
5.3.4 Setting of the generator’s nominal values.....................................................................40
5.3.5 Voltage transformer connection for residual voltage measuring (3pha/e-n/1:1)...........41
5.3.6 Nominal frequency ........................................................................................................41
5.3.7 Selection between vector surge function or df/dt supervision.......................................41
5.3.8 Display of the activation storage ...................................................................................41
5.3.9 Parameter changeover switch/external triggering of the fault recorder ........................42
5.4 Protection parameter “Mains decoupling” .........................................................................43
5.4.1 Parameter setting of “Over- and under voltage functions”............................................43
5.4.2 Number of measuring repetitions (T) for frequency functions.......................................43
5.4.3 Threshold values of frequency supervision...................................................................44
5.4.4 Tripping delays for the frequency elements..................................................................44
5.4.5 Parameter setting for vector surge supervision or df/dt speed .....................................44
5.4.6 Settable threshold .........................................................................................................46
5.5 Protection parameter “Over current” .................................................................................46
5.5.1 Pickup value for phase over current element................................................................46

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5.5.2 Time current characteristics for phase over current element .......................................46
5.5.3 Trip delay or time factor for phase over current element..............................................46
5.5.4 Reset mode for all tripping characteristics in the phase current path...........................47
5.5.5 Pick-up value for high set element................................................................................47
5.5.6 Trip delay for high set element .....................................................................................47
5.6 Parameter protection earth fault supervision....................................................................48
5.6.1 Pick-up value for residual voltage.................................................................................48
5.6.2 Trip delay for residual voltage (only MRG3-IU0 and MRG3-U0)..................................48
5.6.3 Pick-up value for earth fault element............................................................................48
5.6.4 WARN/TRIP changing-over..........................................................................................48
5.6.5 Time current characteristics for earth fault element (only MRG3-IE)...........................48
5.6.6 Trip delay or time multiplier for earth fault element ......................................................49
5.6.7 Reset mode for tripping characteristics in earth current path.......................................49
5.6.8 Pick-up value for earth faults resp. earth short circuit fast trips....................................49
5.6.9 Trip delay for earth fault s resp. earth short circuit fast trips ........................................49
5.6.10 COS/SIN-measurement............................................................................................49
5.7 More Settings....................................................................................................................50
5.7.1 Circuit breaker failure protection...................................................................................50
5.7.2 Adjustment of the slave address...................................................................................50
5.7.3 Setting of Baud-rate (applies for Modbus Protocol only)..............................................50
5.7.4 Setting of parity (applies for Modbus Protocol only).....................................................50
5.8 Fault recorder ...................................................................................................................51
5.8.1 Adjustment of the fault recorder....................................................................................51
5.8.2 Number of the fault recordings .....................................................................................51
5.8.3 Adjustment of trigger occurrences................................................................................51
5.8.4 Pre-trigger time.............................................................................................................51
5.8.5 Adjustment of the clock.................................................................................................52
5.9 Additional functions...........................................................................................................53
5.9.1 Blocking of protection functions and assignment of the output relays..........................53
5.10 Indication of measuring values.........................................................................................55
5.10.1 Measuring indication for mains decoupling ..............................................................55
5.10.2 Storage of min./max. values .....................................................................................55
5.10.3 Unit of the measuring values displayed....................................................................56
5.10.4 Indication of values measured for over current - and earth fault protection............56
5.10.5 Units of the measuring values ..................................................................................57
5.10.6 Indication of fault data...............................................................................................58
5.10.7 Fault recorder............................................................................................................58
5.10.8 Erasure of fault storage ............................................................................................59
5.10.9 Reset.........................................................................................................................60
5.10.10 Delete of disturbance records...................................................................................60
6. Maintenance and Commissioning............................................................61
6.1 Connection of aux. voltage...............................................................................................61
6.2 Testing of the output relays and LEDs .............................................................................61
6.3 Checking the set values....................................................................................................62
6.4 Test with transformer secondary current (Secondary injection test)..............................62
6.4.1 Equipment required to test voltage functions ...............................................................62
6.4.2 Test circuit.....................................................................................................................63
6.4.3 Checking of the input circuits and measuring functions ...............................................64
6.4.4 Checking the pick-up and release values for over/under voltage.................................64
6.4.5 Checking of the tripping delay time for over/under voltage ..........................................64
6.4.6 Checking of the pick-up and release values for over/under frequency ........................65
6.4.7 Checking of the tripping delay time for over/under frequency s ...................................65
6.4.8 Checking of the vector surge function ..........................................................................65
6.5 Test with transformer secondary current (Secondary injection test)..............................66
6.5.1 Equipment required to test voltage functions ...............................................................66
6.5.2 Test circuit for the current function ...............................................................................67
6.5.3 Checking the input circuits and measured values........................................................67
6.5.4 Checking the operating and resetting values of the relay ............................................68
6.5.5 Checking of the tripping delay ......................................................................................68
6.5.6 Checking the high set element of the relay ..................................................................68
6.6 Example of a test circuit for MRG3-IER-relay with earth current directional feature......69

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DOK-TD-MRG3, Rev. D 5
6.7 Checking the external blocking and reset inputs ..............................................................70
6.7.1 Test of the CB failure protection....................................................................................70
6.8 Primary injection test.........................................................................................................70
6.9 Maintenance......................................................................................................................70
7. Technical data............................................................................................71
7.1 Measuring input voltage....................................................................................................71
7.1.1 Influences on the voltage measurement.......................................................................71
7.2 Frequency measurement..................................................................................................71
7.2.1 Influences on the frequency measurement...................................................................71
7.3 Measuring input: phase current.........................................................................................72
7.3.1 Influences on the current measurement .......................................................................72
7.4 Measuring input: Residual voltage....................................................................................72
7.4.1 Influences on the residual voltage measuring...............................................................72
7.5 Measuring input: Earth current..........................................................................................73
7.5.1 Influences on the earth current measuring ...................................................................73
7.6 Common data....................................................................................................................74
7.7 Output relays.....................................................................................................................74
7.8 Setting ranges and steps ..................................................................................................75
7.8.1 System parameter.........................................................................................................75
7.8.2 Parameter protection: Voltage, Frequency, df/dt protection .........................................77
7.8.3 Time over current protection .........................................................................................79
7.8.4 Earth fault supervision...................................................................................................80
7.8.5 Earth fault supervision with directional feature .............................................................81
7.8.6 Determination of the earth fault direction (MRG3-IER).................................................81
7.8.7 Residual voltage protection...........................................................................................82
7.8.8 CB failure protection......................................................................................................82
7.8.9 Interface parameter.......................................................................................................82
7.8.10 Parameter for the fault recorder................................................................................83
7.8.11 Output relay...............................................................................................................83
7.8.12 Inverse time over current protection relay.................................................................84
7.9 Inverse time characteristics...............................................................................................85
8. Order form..................................................................................................88
Important Note!
The description “digital Multi-Function Relay MR” is part of the present description including those
chapters that are valid for all devices of this High Tech Line such as:
Characteristics and features
Technique of MR –Relays
Operation and settings
Housing
Maintenance
General technical data
Technical data subject to change without notice!

SEG Electronics GmbH Manual MRG3
6 DOK-TD-MRG3, Rev. D
1.Overview and Application
The MRG3 is a universal mains decoupling device that covers all the protection functions which are
required by VDEW and by most other utilities for the mains parallel operation of power stations
such as:
over/and under voltage protection,
over/and under frequency protection,
extremely fast generator mains decoupling in case of vector surges or rate of change of
frequency df/dt
The MRG3 can furthermore be equipped with a multi-purpose over current time and earth fault pro-
tection re-lay and it has been designed as to be also used for grids with isolated and compensated
star points respectively. It is applicable for the mains parallel operation of power generating gen.-
sets and includes the following protection functions.
Independent (Definite) time over current relay,
dependent time over current relay with selectable characteristics, independent short
circuit protection
two-element (low and high set) earth fault protection with definite or inverse time
characteristics,
integrated determination of earth fault direction for application to power system networks
with isolated star point or earth fault compensation (ER/XR-relay type),
two-step protection for the residual voltage
For applications where only individual protection functions are required SEG Electronics GmbH
can, of course, also offer the following MR-relays as individual devices:
MRU3-1 four step independent over-/ and under-voltage protection (also used for
generator earth fault protection).
MRU3-2 two step independent over-/ and under-voltage protection with evaluation
of the symmetrical voltage components.
MRF3 four step independent over/ and under- frequency protection and two step
frequency gradient supervision df/dt.
MRI3-I Independent (Definite) time over current relay, inverse time over current
relay with selectable tripping characteristics, independent short circuit
protection
MRI3-E two-element (low and high set) earth fault protection with definite or inverse
time characteristics,
General Note
The description of the digital multifunction relay MR is a part of the present description and it in-
cludes technical data and details valid for most of the MR devices.

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DOK-TD-MRG3, Rev. D 7
2.Features and Characteristics
Microprocessor technology with watchdog function.
Effective analog low pass filter for suppressing harmonics when measuring frequency, df/dt
and vector surge.
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.
Integrated functions for voltage, frequency, df/dt and vector surge in one device.
Voltage supervision each with two step under-/and overvoltage detection.
Frequency supervision with three step under-/or over frequency (user setting).
Completely independent time settings for voltage and frequency supervision.
User configurable vector surge measurement 1-of-3 or 3-of-3.
Adjustable voltage threshold value for the blocking of frequency-, df/dt or vector surge
measuring.
Independent time over current protection.
Selectable protective functions between:
- definite time over current relay and
- inverse time over current relay,
Selectable inverse time characteristics according to IEC 255-4:
- Normal Inverse (type A)
- Very Inverse (type B)
- Extremely Inverse (type C)
Further characteristics:
- Long Time Inverse,
- RI-Inverse
- RXIDG characteristic
Reset mode selectable for inverse time characteristics.
Definite time element for short circuit fast trip.
Two-step earth fault supervision.
Optionally: sensitive, watt metric directional earth fault detection with measurement of the
residual voltage.
Optionally: supervision of the residual voltage in two steps.
Two parameter sets.
Circuit breaker failure protection with release for subordinate protection.
Functions for the backward blocking.
Display of all measuring values and setting parameters for normal operation as well as
tripping via alphanumerical display and LEDs.
Display of measuring values as primary quantities,
Setting of the switching points for current and voltage measured in per cent.
Voltage fail-safe storage and indication of tripping values in an error memory, 16 times
(voltage fail-safe).
Recording of up to four fault events with time stamp in Comtrade format according to
IEC602555-25.
For the blocking of individual functions via external blocking input, parameters can be set
according to requirement.
Suppression of indication after completed activation (LED flash).
Free assignment of the output relays.
Display of date and time.
Requirements in compliance with VDE 0435, part 303 and IEC 255.
Possibility of serial data exchange via RS485 inter-face possible; alternatively with
RS485 Pro-Open Data Protocol or Modbus Protocol.

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3.Design
3.1 Connections
3.1.1 Connection Diagrams
Figure 3.1: Connection diagram “Mains decoupling”
The measuring circuits can optionally be star- or delta connected (see chapter 4.3.1)
Figure 3.2: MRG3-I Connection diagram “Mains decoupling with time over current protection

Manual MRG3 SEG Electronics GmbH
DOK-TD-MRG3, Rev. D 9
Figure 3.3: MRG3-I Connection diagram “Mains decoupling with time over current protection”
Figure 3.4: Connection diagram with time over current protection and earth fault protection Holmgreen circuit
This connection can be used with three existing phase current transformers when combined phase
and earth-current measuring is required. Disadvantage of the Holmgreen-circuit:
At saturation of one or more C.Ts the relay seemingly detects an earth current.

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10 DOK-TD-MRG3, Rev. D
Figure 3.5: Connection diagram with time over current protection and earth fault directional feature