Seg MRM3 User manual

MRM3
PROTECTION TECHNOLOGY
MADE SIMPLE
MOTOR PROTECTION RELAY
HighTECH Line
MOTOR PROTECTION RELAY
Revision: B
Original document
English
MANUAL

SEG Electronics GmbH Manual MRM3-2
2 DOK-TD-MRM3-2, 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 MRM3-2 SEG Electronics GmbH
DOK-TD-MRM3-2, Rev. B 3
Contents
1. Introduction and Application ......................................................................6
2. Characteristics and Features......................................................................7
3. Design...........................................................................................................8
3.1 Connections ........................................................................................................................8
3.1.1 Analog Inputs ..................................................................................................................9
3.1.2 Output Relays..................................................................................................................9
3.1.3 Digital Inputs..................................................................................................................10
3.1.4 Low/High Range of the Digital Inputs............................................................................10
3.2 Front plate.........................................................................................................................11
3.2.1 Indicating LEDs.............................................................................................................12
3.2.2 Adjusting LEDs..............................................................................................................12
3.3 Analog part........................................................................................................................12
3.4 Digital part.........................................................................................................................13
4. Working Principle ......................................................................................14
4.1 Start Recognition...............................................................................................................14
4.1.1 Criteria for Blocking the Start ........................................................................................16
4.2 Starting time......................................................................................................................18
4.3 Thermal Image..................................................................................................................18
4.4 Requirement on the Main Current Transformers..............................................................19
5. Operation and Adjustments......................................................................20
5.1 Displayed text for parameter settings ...............................................................................20
5.2 Setting Procedure .............................................................................................................21
5.3 System parameters...........................................................................................................21
5.3.1 Presentation of Measuring Values as Primary Quantities on the Display (Iprim Phase) 21
5.3.2 Rated -Frequency..........................................................................................................21
5.3.3 Operating Hour Meter (h)..............................................................................................21
5.3.4 Number of Motor Starts (No.)........................................................................................21
5.3.5 Indication of pickup........................................................................................................21
5.3.6 Parameter Set Changeover Switch (P2).......................................................................22
5.4 Protection Parameters ......................................................................................................22
5.4.1 Thermal Overload Protection (k x IB)............................................................................22
5.4.2 Warning/Tripping with thermal Overload.......................................................................22
5.4.3 Tripping Delay for Thermal Overload............................................................................22
5.4.4 Heating Period Constant Wand Cooling-Down Time Factor C...................................22
5.4.5 t2x and t6x Minimal Trip Time During the Starting Process..........................................23
5.4.6 Phase Undercurrent Element (I<) .................................................................................23
5.4.7 Phase Over current Element (I>) ..................................................................................23
5.4.8 Trip Characteristics for the Phase Over current Element (I>+CHAR) ..........................23
5.4.9 Tripping Time or Time Factor for the Phase Over current Element (I>+t>)..................24
5.4.10 Reset Mode for the Trip Characteristics in the Phase Current Path (I>+CHAR+t>).24
5.4.11 Phase Short-Circuit Trip (I>>) and (I>>+Start)..........................................................24
5.4.12 Negative Phase Sequence........................................................................................25
5.4.13 Earth Fault Element (IE>)..........................................................................................25
5.4.14 Switching Over Warning/Tripping..............................................................................25
5.4.15 Trip Characteristics for the Earth-Fault Element (IE>+CHAR) .................................25
5.4.16 Tripping Time or Time Factor for the Earth Fault Element (IE>+t>) .........................26
5.4.17 Reset Time for the Earth Fault Element (IE>+CHAR+t>).........................................26
5.4.18 Tripping Time for the CB Failure-Protection (CB+t>)................................................26
5.4.19 External Trip (delayed)(Trip+t>)................................................................................26
5.4.20 Trip Blocking in case of Excessive Phase Current (Trip+Block)...............................26
5.5 Start Supervision...............................................................................................................27
5.5.1 Duration of a Start Cycle (No.+Start) ............................................................................27
5.5.2 Number of Starts per Cycle (No.+Start)........................................................................27
5.5.3 Start Blocking Time (Start+Block+t>)............................................................................27
5.5.4 Characteristic for the Starting Time...............................................................................27
5.5.5 Rated starting current I_Start........................................................................................27
5.5.6 Maximal Start Time (Start+t>).......................................................................................28

SEG Electronics GmbH Manual MRM3-2
4 DOK-TD-MRM3-2, Rev. B
5.5.7 Start-up recognition time or Motor Running time..........................................................28
5.5.8 Stopping time................................................................................................................28
5.6 Interface Parameters........................................................................................................28
5.6.1 Adjustment of the Slave-Address (RS).........................................................................28
5.6.2 Adjustment of the Baud-Rate (only for Modbus Protocol)............................................28
5.6.3 Adjustment of the Parity (only for Modbus-Protocol)....................................................28
5.7 Recorder (FR)...................................................................................................................29
5.7.1 Fault Recorder or Disturbance Recorder......................................................................29
5.7.2 Number of Fault Recordings.........................................................................................30
5.7.3 Adjustment of the Trigger Event...................................................................................30
5.7.4 Pre-Trigger Time (Tvor)..................................................................................................30
5.8 Setting of the Clock...........................................................................................................31
5.9 Additional Functions .........................................................................................................32
5.9.1Blocking of the Protective Functions.............................................................................32
5.9.2 Allocation of the Reset Functions.................................................................................33
5.9.3 Allocation of the Output Relays ....................................................................................34
5.10 Measuring Value and Fault Indications ............................................................................36
5.10.1 Measuring Value Indications.....................................................................................36
5.10.2 Units of the Displayed Measuring Values.................................................................36
5.10.3 Indication of the Fault Data.......................................................................................36
5.10.4 Fault Memory............................................................................................................37
5.11 Reset.................................................................................................................................38
5.11.1 Erasure of the Fault Memory....................................................................................38
5.11.2 Reset of the Thermal Memory..................................................................................38
5.12 Digital Inputs.....................................................................................................................39
5.12.1 Parameter Set Changeover Switch ..........................................................................39
5.12.2 External Trigger of the Fault Recorder .....................................................................39
5.12.3 Recognition of “Motor Running” Condition ...............................................................39
5.12.4 Undelayed External Trip...........................................................................................39
5.12.5 Delayed External Trip ...............................................................................................39
6. Notes on Relay Tests and Commissioning .............................................40
6.1 Connection of the auxiliary voltage...................................................................................40
6.2 Testing of Output Relays and LEDs .................................................................................40
6.3 Test circuit for MRM3-2 ....................................................................................................41
6.3.1 Checking of Input Circuits and of the Measuring Values..............................................41
6.3.2 Testing the START-STOP-RUNNING Recognition......................................................41
6.3.3 Testing the Pick-Up and Disengaging Values ..............................................................42
6.3.4 Testing the maximum starting time...............................................................................42
6.3.5 Testing the thermal image ............................................................................................42
6.3.6 Testing the Control Inputs.............................................................................................42
6.3.7 Testing the CB Failure Protection.................................................................................42
6.4 Primary Test......................................................................................................................43
6.5 Maintenance .....................................................................................................................43
7. Technical Data............................................................................................44
7.1 Measuring input ................................................................................................................44
7.2 Common data ...................................................................................................................44
7.3 Setting ranges and steps..................................................................................................45
7.3.1 System parameter ........................................................................................................45
7.3.2 Time over current protection.........................................................................................46
7.3.3 Load Unbalance Protection ..........................................................................................48
7.3.4 Earth fault protection.....................................................................................................49
7.3.5 Circuit breaker failure protection...................................................................................50
7.3.6 External trip delay.........................................................................................................50
7.3.7 Trip blocking beginning with the adjusted rated current...............................................50
7.3.8 Start parameter.............................................................................................................51
7.3.9 Interface parameter ......................................................................................................52
7.3.10 Fault recorder parameter..........................................................................................52
7.4 Tripping characteristics.....................................................................................................53
7.4.1 Tripping characteristic for max. starting time................................................................53
7.4.2 Thermal image..............................................................................................................54

Manual MRM3-2 SEG Electronics GmbH
DOK-TD-MRM3-2, Rev. B 5
7.4.3 Initial load factor ............................................................................................................54
7.4.4 Tripping of t2x and t6x - times.......................................................................................55
7.4.5 Inverse time over current protection..............................................................................56
7.4.6 Trip characteristics........................................................................................................57
7.4.7 Inverse Time Characteristic for Load Unbalance..........................................................61
7.5 Output relays.....................................................................................................................61
8. Order form..................................................................................................62

SEG Electronics GmbH Manual MRM3-2
6 DOK-TD-MRM3-2, Rev. B
1.Introduction and Application
The motor protection relay MRM3-2 offers reliable protection for LV and MV motors which are ei-
ther operated via power contactors or power circuit breakers.
The following functions are integrated into this relay:
Overload protection acc. to IEC 255-8 in consideration of the initial load factor
(thermal image)
Definite undercurrent protection
Definite time over current protection (DMT)
Inverse time over current protection (IMT) with select-able trip characteristics
Short-circuit protection
Load unbalance supervision with definite or inverse trip characteristics
Earth-fault detection with suppression of harmonics
The MRM3-2 recognizes the “Start-Up“ and “Motor Running“ phase.
Motors with a limited number of starts can be controlled by the start limiting function of the relay.
The earth-fault supervision is either realized in Holm-green connection or by means of a core-type
current transformer.
The motor can be stopped in delayed or undelayed mode via digital inputs.
The MRM3-2 is available with rated currents of 1A or 5A.
Important:
For additional common data of all MR-relays please refer to manual "MR - Digital Multifunctional re-
lays". On page 45 of this manual you can find the valid software versions.

Manual MRM3-2 SEG Electronics GmbH
DOK-TD-MRM3-2, Rev. B 7
2.Characteristics and Features
Microprocessor technology with self-supervision,
Measuring of phase currents as RMS value,
Digital filtering of the earth current with discrete Fourier analysis, by which the influence of
interference signals, such as harmonics and transient DC components during an earth-
fault are suppressed.
Two sets of parameters,
Operating hour meter,
Complies with the requirements of IEC 255-8, VDE435, part 301-1 for overload relays,
Definite time undercurrent protection,
Selectable protective functions : Definite time over-current protection (DMT) and inverse
time over current protection (IMT)
Selectable IMT trip characteristics of IEC 255-4:
- Normal inverse (Type A)
- Very inverse (Type B)
- Extremely inverse (Type C)
- Special-purpose characteristics
Reset mode for DMT/IMT trip characteristics is selectable,
Definite element for short-circuit high-speed trip
Single-step earth fault supervision,
Load unbalance protection with inverse or definite trip characteristics (NPS),
CB failure protection,
Display of the measuring values as primary quantities,
Measuring of the phase currents during short-circuit free operation,
Blocking of the individual protective elements or the trip elements can be set freely,
The protective functions can be freely allocated to the output relays. (Relay Matrix),
Suppression of an LED indication after activation (LED flash),
„Manual/Automatic“ reset function of the trip elements adjustable via the configuration
matrix,
Saving of trip values and the switch-off times (tCBFP) of 25 fault events (voltage fail-safe)
Recording of up to 8 fault events with time stamp,
Display of date and time,
Trip via digital inputs,
Rack mounting, with self-acting short-circuit mechanism for CT circuits,
Possibility of serial data exchange via the RS485 interface, optionally with RS485
Pro-Open-Data Protocol or Modbus Protocol.

SEG Electronics GmbH Manual MRM3-2
8 DOK-TD-MRM3-2, Rev. B
3.Design
3.1 Connections
Figure 3.1: Connection Diagram MRM3-2
Figure 3.2: Measuring of phase currents and earth current detection in Holmgreen connection (IE)
This kind of connection can be used where three phase CTs are available and a combination of
phase and earth current measuring is required.

Manual MRM3-2 SEG Electronics GmbH
DOK-TD-MRM3-2, Rev. B 9
Figure 3.3: Measuring of earth current with core-type CT (IE)
With the combination of phase and earth current measuring, CTs to be connected according to
Figure 3.2. and Figure 3.3.
3.1.1 Analog Inputs
The analog input signals of the phase currents IL1 (B3 - B4), IL2 (B5 - B6), IL3 (B7 - B8) and the earth
current IE(B1 - B2) are fed to the protection device via separate input CTs.
The current measuring quantities are galvanic decoupled, analogously filtered, and then fed to the
analog/digital converter.
3.1.2 Output Relays
The MRM3-2 has 5 output relays. Two of these relays with two change-over contacts and three re-
lays with one change-over contact each are used for signaling. The protective functions can be
freely allocated except of those for the self-supervision relay.
Relay 1: C1, D1, E1 and C2, D2, E2
Relay 2: C3, D3, E3 and C4, D4, E4
Relay 3: C5, D5, E5
Relay 4: C6, D6, E6
Relay 5: Self-supervision C7, D7, E7
All relays are operating according to the n. o. principle with the exception of the self-supervision re-
lay, which operates acc. to the n. c. principle.

SEG Electronics GmbH Manual MRM3-2
10 DOK-TD-MRM3-2, Rev. B
3.1.3 Digital Inputs
The MRM3-2 has 7 digital inputs with fixed functions. All inputs have a common reference point :
Terminal D8. (See Chapter 3.1)
No
Terminal
Function
Coding Plug
1
C8
External reset
2
2
E8
External blocking
1
3
A2
Parameter set change-over switch
3
4
A5
External trigger for the fault recorder
4
5
A6
Identification „Motor Running“
7
6
A7
Ext. trigger, undelayed
6
7
A8
Ext. trigger, delayed
5
3.1.4 Low/High Range of the Digital Inputs
The MRM3-2 is equipped with a wide-range power supply unit and hence the supply voltage is
freely selectable. The switching threshold of the digital inputs, however, has to be fixed in compli-
ance with the supply voltage. Two different switching thresholds can be adjusted:
Range
Plug
U not active
U active
Low
Plugged in
<= 8V
>= 10V
High
Open
<= 60V
>= 80V
Figure 3.4: Coding Plug