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MANUAL HighTECH Line PROTECTION TECHNOLOGY MADE SIMPLE MRM3 MOTOR PROTECTION RELAY MOTOR PROTECTION RELAY Original document English Revision: B...
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SEG Electronics GmbH Manual MRM3-2 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.
Manual MRM3-2 SEG Electronics GmbH Contents Introduction and Application ..............6 Characteristics and Features ..............7 Design ......................8 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 Front plate .........................
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SEG Electronics GmbH Manual MRM3-2 5.5.7 Start-up recognition time or Motor Running time ............28 5.5.8 Stopping time ........................ 28 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...
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Manual MRM3-2 SEG Electronics GmbH 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 Output relays ........................
SEG Electronics GmbH Manual MRM3-2 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: ...
Manual MRM3-2 SEG Electronics GmbH 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.
SEG Electronics GmbH Manual MRM3-2 3. Design 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 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 I...
SEG Electronics GmbH Manual MRM3-2 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) Terminal Function Coding Plug External reset External blocking Parameter set change-over switch External trigger for the fault recorder Identification „Motor Running“...
SEG Electronics GmbH Manual MRM3-2 The LEDs , h, RS and FR on the MRM3-2 emit a yellow light, all other LEDs are bi-colored. The LEDs at the left next to the alphanumerical display give a green light during measuring and a red one when a fault signal occurs.
Manual MRM3-2 SEG Electronics GmbH Digital part The protection relay is equipped with a powerful micro-controller, being the core element of the pro- tection unit. With this micro-controller all tasks are completely digitally processed, from discretisa- tion of the measuring quantities to protective tripping.
SEG Electronics GmbH Manual MRM3-2 4. Working Principle Start Recognition The MRM3-2 monitors the flow of the current from which the following operational conditions of the motor are gathered. STOP START RUNNING Figure 4.1: Different Start-Up Behavior of Motors STOP - Condition: If no current can be measured (I <...
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Manual MRM3-2 SEG Electronics GmbH Overload Threshold: This corresponds to the permissible thermal continuous current k x IB and is adjusted by the parameter of the thermal image. Starter Recognition Time: This adjustable time has only to be extended for special start procedures in order to prevent that the RUNNING conditions are indicated too early in advance.
SEG Electronics GmbH Manual MRM3-2 4.1.1 Criteria for Blocking the Start Number of monitored starts : The MRM3-2 is equipped with a flexible supervision element which can limit the sequence of pos- sible starts. A start should be prevented if it is obvious that it is likely to be interrupted due to overload so that in total the down-time can be curtailed.
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Manual MRM3-2 SEG Electronics GmbH Figure 4.4: Relation Start Period/Start Blocking Time with firm Start Blocking Time Thermal Image A start is always possible as long as there is enough thermal reserve for a start. This start limitation is a dynamic one and is orientated on the data the thermal image is parameterized with. For this the MRM3-2 detects the average thermal load of the latest starts.
SEG Electronics GmbH Manual MRM3-2 Starting time With certain applications it is possible that the starting phase of the engines is extended. One rea- son for this insufficient terminal voltage which may be caused by the high starting current or by a high grid load in general.
Manual MRM3-2 SEG Electronics GmbH Requirement on the Main Current Transformers The CTs chosen have a considerable influence on the accuracy of the protective system. In order to select the right type of transformer, the requirements and conditions on site have to be consid- ered carefully.
SEG Electronics GmbH Manual MRM3-2 5. Operation and Adjustments Displayed text for parameter settings Function Displayed Text Related LED References Normal operation Exceeding the measuring range max. Sec. transf. currents indication L1, L2, L3,E Chap. 5.3.1 Rated frequency f = 50 / f = 60 Chap.
Manual MRM3-2 SEG Electronics GmbH Setting Procedure <SELECT/RESET> short advancing the indication long reset <ENTER> Saving of an entry Before parameters can be set a password is inquired (see chapter 4.4 of description ”MR – Digital Multifunction Relay”). System parameters 5.3.1 Presentation of Measuring Values as Primary Quantities on the Dis-...
SEG Electronics GmbH Manual MRM3-2 5.3.6 Parameter Set Changeover Switch (P2) By means of this switch two different parameter sets can be activated. The changeover procedure can be realized either by the software or via the digital input (A2). If the parameter set changeover switch is adjusted to ”SET2“, the active parameter set can be changed to ”SET1“...
Manual MRM3-2 SEG Electronics GmbH 5.4.5 t2x and t6x Minimal Trip Time During the Starting Process. With this parameter the fastest trip time during the start-up phase is limited for the thermal image. If the selected pick-up value k x I is exceeded by two times or six times, the characteristic breaks to definite time.
SEG Electronics GmbH Manual MRM3-2 5.4.9 Tripping Time or Time Factor for the Phase Over current Element (I>+t>) Normally, after change of the trip characteristics, the tripping time or the time factor also has to be changed accordingly. In order to avoid an unsuitable combination between trip characteristics and tripping time or time factor, the following measures are initiated by the MRM3-2: The LED for adjustment of the tripping time or time factor (I>...
Manual MRM3-2 SEG Electronics GmbH 5.4.12 Negative Phase Sequence Load unbalance can, for example, be caused by a phase failure or fault in a one motor winding. Load unbalances give rise to negative phase sequence currents in the stator, causing odd harmon- ics in the stator winding and even harmonics in the rotor winding.
SEG Electronics GmbH Manual MRM3-2 5.4.16 Tripping Time or Time Factor for the Earth Fault Element (IE>+t>) The setting procedure outlined in chapter 5.4.9 applies here as well. 5.4.17 Reset Time for the Earth Fault Element (IE>+CHAR+t>) The setting procedure outlined in chapter 5.4.10 applies here as well.
Manual MRM3-2 SEG Electronics GmbH Start Supervision The MRM3-2 can offer two start supervision methods: Automatically by means of the thermal load By a limited number of starts per time interval 5.5.1 Duration of a Start Cycle (No.+Start)
SEG Electronics GmbH Manual MRM3-2 5.5.6 Maximal Start Time (Start+t>) Exceedingly long acceleration can only be recognized if the threshold k*I is once overshot after the STOP threshold was exceeded. With the setting "DEFT" The time meter for the max. start time is activated upon exceeding of the threshold k*I >.
Manual MRM3-2 SEG Electronics GmbH Recorder (FR) 5.7.1 Fault Recorder or Disturbance Recorder The existing store can be utilized in two ways: Not to be overwritten Previous recordings will not be overwritten. When there is no memory space left, further recordings are not possible.
SEG Electronics GmbH Manual MRM3-2 Each of the storage segments have a fixed storage time where the time before the trigger event can be defined. Via the RS485 interface the data can be read out by means of a PC provided with HTL/PL-Soft4.
Manual MRM3-2 SEG Electronics GmbH Setting of the Clock When date and time are set, the LED „ “ is on. The following method is used: Date: year Y=00 month M=00 D=00 time: hour h=00 minute m=00 second s=00 Immediately when the supply voltage is applied the clock starts with the respective date and time.
SEG Electronics GmbH Manual MRM3-2 Additional Functions 5.9.1 Blocking of the Protective Functions Blocking of the protective functions After voltage has been applied to blocking input D8/E8, the intended reaction for each of the protective functions can be defined individually. (Observe voltage adjustment !) See chapter 3.1.4...
Manual MRM3-2 SEG Electronics GmbH 5.9.2 Allocation of the Reset Functions When setting of the parameters for the blocking function is completed you are in the allocation mode for the reset functions. Whether the assigned relay should be reset manually or automatically after activation or trip can be allocated to each of the activation or trip elements.
SEG Electronics GmbH Manual MRM3-2 5.9.3 Allocation of the Output Relays The MRM3-2 has five output relays. The fifth output relay is an alarm relay for the self-supervision and its al-location is fixed; it is operated acc. to the closed circuit principle.
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Manual MRM3-2 SEG Electronics GmbH Relay functions Output relays Displayed Corresponding LED figures Symbol Function > > red Alarm _ 2 _ _ > x k Alarm _ 2 _ _ > green > x k Tripping 1 _ _ _ >...
SEG Electronics GmbH Manual MRM3-2 5.10 Measuring Value and Fault Indications 5.10.1 Measuring Value Indications The following measuring values can be displayed during normal operation: Current in phase 1 (LED L1 green), Current in phase 2 (LED L2 green), ...
Manual MRM3-2 SEG Electronics GmbH 5.10.4 Fault Memory In case of actuation or tripping of the relay, the fault values and times are stored in a voltage fail- safe way. The MRM3-2 has a fault value memory covering up to 25 fault events. If this number is exceeded, the eldest data set is then overwritten.
SEG Electronics GmbH Manual MRM3-2 3. Values recorded after a tripping action Tripping current in Phase 1, Tripping current in Phase 2, Tripping current in Phase 3, Tripping value for earth current E, Tripping value for load-unbalance current I2, ...
Manual MRM3-2 SEG Electronics GmbH 5.12 Digital Inputs 5.12.1 Parameter Set Changeover Switch When voltage is applied to this input it is changed over to the other parameter set. 5.12.2 External Trigger of the Fault Recorder Via this input fault recording can be triggered without the MRM3-2 necessarily recognizing a trip.
SEG Electronics GmbH Manual MRM3-2 6. Notes on Relay Tests and Commissioning Connection of the auxiliary voltage To prevent destruction of the relay during tests the following has to be observed: The aux. voltage supply of the relay must be within the permissible ranges.
Manual MRM3-2 SEG Electronics GmbH Test circuit for MRM3-2 For testing the MRM3-2 relays only one power source is necessary. Figure 6.1 shows a simple ex- ample of a single-phase testing circuitry with controllable power source for testing the unit.
SEG Electronics GmbH Manual MRM3-2 6.3.3 Testing the Pick-Up and Disengaging Values For optimal protection many functions in this motor protection relay are interlinked and hence it is not possible to have all protective elements tested independently from each other.
Manual MRM3-2 SEG Electronics GmbH Primary Test As a rule, tests with currents at the CT primary side (real test) can be performed in the same way as tests with secondary currents. It is recommended to carry out primary tests only as an exception and only if it is absolutely necessary (for very essential protective facilities) because in some cases the costs involved and the strain on the system can be rather high.
SEG Electronics GmbH Manual MRM3-2 7. Technical Data Measuring input Rated data: Rated current I 1A or 5A Rated frequency f 50/60 Hz adjustable Power consumption in current path: at I = 1 A 0.2 VA at I = 5 A 0.1 VA...
Manual MRM3-2 SEG Electronics GmbH Setting ranges and steps 7.3.1 System parameter *) One parameter can be marked by several LEDs Parameter LED * Setting range Range Step Tole- rance Transformer ratio L1 L2 L3 SEK Displayed in x I 0.002-0.200...
SEG Electronics GmbH Manual MRM3-2 7.3.2 Time over current protection Parameter Setting range Notes Range Step Tolerance 3% of setting Therm. Permissi- 0.20...4.00 0.01; ble contin. current EXIT Step switched 0.02; value or 10mA k x I 0.05; 0.1 x I Overload factor 0.80...1.20...
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Manual MRM3-2 SEG Electronics GmbH Parameter Setting range Notes Range Step Tolerance VINV very inverse EINV extremely in- RINV verse LINV RI-inverse Long-term in- verse 3% of the set- Time delay I>+t> at DEFT: 0.04-1.00 0.02 0.04 ...260 Time delay in s 1.00-2.00...
Manual MRM3-2 SEG Electronics GmbH 7.3.4 Earth fault protection Parameter Setting Notes Range Step Tolerance range 3% of the set- Earth fault 0,01...2,0 pickup value x I 0.010 - 0.050 0.001 E> protection EXIT element blocked 0.050 - 0.100 0.002 ting value or 0.5% of the...
SEG Electronics GmbH Manual MRM3-2 7.3.5 Circuit breaker failure protection Parameter Setting Notes Range Step Tolerance range CB+t> 0.1...2.00 CB time 0.10-1.00 0.02 EXIT Step switched off 1.00-2.00 0.05 7.3.6 External trip delay Parameter Setting Notes Range Step Tolerance range 3% of the set-...
Manual MRM3-2 SEG Electronics GmbH 7.3.8 Start parameter Parameter LED * Setting Notes Range Step Tolerance range 2s for one Start blocking Start+N AUTO* Supervision by ther- start cycle reserve Supervision by inter- 1.0... 60.0 val time: Duration of the start...
Manual MRM3-2 SEG Electronics GmbH Tripping characteristics 7.4.1 Tripping characteristic for max. starting time The formula for calculating the tripping characteristic is: Inverse Time Characteristic ∙ this applies if I/I_Start > = 0,707 _ = 2 x ts this applies if I/I_Start<...
SEG Electronics GmbH Manual MRM3-2 7.4.2 Thermal image The formula for calculating the trip characteristics is as follows: − p ∗ k ) = ∙ In [ ] for p < ∩ p ≤ 1 ∙ k ) −...
Manual MRM3-2 SEG Electronics GmbH 7.4.4 Tripping of t2x and t6x - times 1000,0 [min] 100,0 = 180 min = 100 min 10,0 = 10 min = 1 min = 0.5 min I / I Figure 7.3: Limitation of tripping time 2 x I...
SEG Electronics GmbH Manual MRM3-2 7.4.5 Inverse time over current protection Trip characteristics acc. to IEC 255-4 or BS 142 Normal inverse (Type A) 0.14 > [ ] = ∙ 0.02 − 1 ...
Manual MRM3-2 SEG Electronics GmbH 7.4.7 Inverse Time Characteristic for Load Unbalance Inverse current time protection = ( / − 1 2 With: t = tripping time [s] T = thermal time constant = measured load unbalance in relation to IN...
SEG Electronics GmbH Manual MRM3-2 8. Order form Motor protection relay MRM3- with thermal image With additional features such as characteristic for maximum starting time, tripping delay of the thermal overload, tripping/warning for thermal overload Phase current rated current Earth fault current...
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Manual MRM3-2 SEG Electronics GmbH Setting list for MRM3-2 Project: Job.-No.: Functional group: = Location: + Relay code: - Relay functions: Password: Date: All settings have to be checked at site and perhaps adjusted to the object to be protected.
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SEG Electronics GmbH Manual MRM3-2 Protection parameters Unit Default Actual setting setting Function Set1/Set 2 Set1 Set 2 Parameter set change-over switch SET1 > Basic current of the thermal overload 0.20 protection Constant 1.00 > + t> Excitation delay of the I >*k - steps...
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Manual MRM3-2 SEG Electronics GmbH Protection Parameters (Contin.) Unit Default Actual setting setting Function Set1/Set2 Set1 Set2 I>> + Pick-up value for the phase short-circuit 0.50 Start element at start I>> + Tripping time of the phase short-circuit 0.04 Start + t>...
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SEG Electronics GmbH Manual MRM3-2 Start parameters Unit Default Actual Function setting setting Function Set1/Set2 Set1 Set2 No.+Start Duration of a start cycle min. Number of starts per cycle Start+Bloc Start blocking time k+t> Start + Characteristic for the starting time...
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Manual MRM3-2 SEG Electronics GmbH Assignment of the blocking functions Function Default setting* Actual setting Set 1 Set 2 Set 1 Set 2 > Overload warning NO_B NO_B > + Overload element NO_B NO_B I< Undercurrent element NO_B NO_B I>...
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SEG Electronics GmbH Manual MRM3-2 Assignment of the Output Relays Function Relay 1 Relay 2 Relay 3 Relay 4 Default Actual Default Actual Default Actual Default Actual setting setting setting setting setting setting setting setting > > Actua- tion >...
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Manual MRM3-2 SEG Electronics GmbH Setting of the Coding Plugs Coding plug Default Actual Default Actual Default Actual setting setting setting setting setting setting Plugged-in Unplugged No function No function Digital inputs Coding plug Function Low/High range for blocking input...
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SEG Electronics GmbH reserves the right to update any portion of this publication at any time. Information provided by SEG Electronics GmbH is believed to be correct and reliable. However, SEG Electronics GmbH assumes no responsibility unless otherwise expressly undertaken.
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