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MC20-X/10-4 

Doc. N°

 MO-0352-ING

 

Microener - Copyright 2010   

 

FW

720.07.01 

Date

09.04.2008

Rev. 

  Pag.

6

 

of

35

 

2.2 - Operation and Algorithms 

 

2.2.1 - Reference Input Values 

 

Display 

Description

Setting Range  Step

Unit

I1

 

100 

Rated Primary current of phase C.T. 

1  -  9999 

I2 

Rated Secondary current of phase C.T. 

1  - 

5  1/5 

Io1

 

100 

Rated Primary current of the tore C.T. detecting earth fault 
current. 

1  -  9999 

Io2

 

Rated secondary current of the tore C.T. detecting earth fault 
current. 

1  - 

5  1/5 

In

 

100 

Reference primary current of the relay  

1  -  9999 

Freq

 

50 

Hz

  System rated frequency 

50  - 

60 

10 

Hz 

 

2.2.2 - Input quantities 

 

2.2.2.1 - Mains Frequency (Freq) 

 

The relay can operate either in 50Hz or 60Hz systems. 
The rated Mains Frequency “ Freq “ must be set accordingly. 

 

2.2.2.2 - Phase Current inputs (I1) 

 

The relay directly displays the r.m.s. value of the Phase Currents “ 

IA

 “, “ 

IB 

”, “ 

IC 

”  flowing in the 

Primary of the input Current Transformers and refers all its measurements to that value. 
To make the relay properly working with any C.T., when programming the relay settings, input the 
value “I1“ of the primary current of the phase C.Ts   
Only phase A and C currents are measured, whereas the current of the phase B is computed as 
vector summation of the currents of the other two phases. 
The algorithm is based on the following considerations coming from well-known vector relations 
among the three-phase currents and the zero sequence current. 

 

-

  In any circumstance – currents balanced or not, sinusoidal or not – it is always true that: 

 

 

0

I

I

I

I

      

1

0

C

B

A

 

 

-

  When no Earth Fault exists (I

0

 = 0) 

 

 

C

A

B

C

B

A

I

I

I

    

    

0

I

I

I

      

2

 

 

The earth fault protection element is independently supplied by the residual current coming either 
from the residual connection of 3 system C.Ts. or from the core balance C.T. 

 

If any Earth Fault is experienced (I

 0) the Earth Fault Protection Element trips independently 

from the phase current measuring elements. 

 

If no Earth Fault is present (I

= 0), the equation (2) is valid, no matter if currents are balanced or 

not, sinusoidal or not.  

 

The third phase current is calculated, in real time, as vector summation of the other two-phase 
currents. 

 

During Faults: 

  

A)  Single phase to earth Fault  Trip of the earth fault element directly measuring the Residual 

Current. 

 

 

 

B)  Two Phase Fault 

 

In any case one of the currents directly measured is involved, so 
the relay trips correctly. 

 

 

 

C)  Two Phase to Earth Fault 

Same as A + B 

 

 

 

D)  Three Phase Fault 

All the three currents are correctly measured (in any case two 
directly). 

 

Summary of Contents for MC20-X/10-4

Page 1: ...MC20 X 10 4 Doc N MO 0352 ING Microener Copyright 2010 FW 720 07 01 Date 09 04 2008 Rev 1 MICROPROCESSOR OVERCURRENT and EARTH FAULT RELAY TYPE MC20 X 10 4 I O Boards OPERATION MANUAL...

Page 2: ..._______________________ 15 2 2 5 13 LCD Display and Buzzer operation ____________________________________________________________________ 15 3 Logic Blocking of Functions______________________________...

Page 3: ...Loading must be compatible with their declared performance 1 6 Protection Earthing When earthing is required carefully check its effectiveness 1 7 Setting and Calibration Carefully check the proper s...

Page 4: ...truction manual of the Manufacturer maintenance must be carried out by specially trained people and in strict conformity with the safety regulations 1 11 Waste Disposal of Electrical Electronic Equipm...

Page 5: ...l Inputs RS485 communication port independent from the RS232 port on front panel Totally draw out execution with automatic C T shorting device Input currents are supplied to 3 current transformers two...

Page 6: ...ents are measured whereas the current of the phase B is computed as vector summation of the currents of the other two phases The algorithm is based on the following considerations coming from well kno...

Page 7: ...nt from I1 2 2 2 4 Algorithm of the time current curves The Time Current Curves are generally calculated with the following equation 1 where t I Actual trip time delay when the input current equals I...

Page 8: ...MC20 X 10 4 Doc N MO 0352 ING Microener Copyright 2010 FW 720 07 01 Date 09 04 2008 Rev 1 Pag 8 of 35 2 2 3 Time Current Curves IEC TU1029 Rev 0...

Page 9: ...MC20 X 10 4 Doc N MO 0352 ING Microener Copyright 2010 FW 720 07 01 Date 09 04 2008 Rev 1 Pag 9 of 35 2 2 4 Time Current Curves IEEE TU1028 Rev 0...

Page 10: ...e Curve SI IEEE Short Inverse Curve BI Operation controlled by Blocking Digital Input Trg Function operation triggers the oscillographic wave form capture see 2 2 3 12 I Minimum phase current pick up...

Page 11: ...vel limited to 40 times In t2xI Trip time delay tIH Trip time delay 2 2 5 3 1 Automatic doubling or Overcurrent thresholds on current inrush For some of the phase Overcurrent functions it is possible...

Page 12: ...ve I IEEE Inverse Curve EI IEEE Extremely Inverse Curve SI IEEE Short Inverse Curve BI Operation controlled by Blocking Digital Input Trg Function operation triggers the oscillographic wave form captu...

Page 13: ...Trip time delay 2 2 5 8 BF F51BF Breaker Failure FuncEnab Enable Disable Enable Options TrR Relay1 Relay1 Relay2 Relay3 Relay4 TripLev No Param No Parameters Timers tBF 0 20 s 0 05 0 75 step 0 01 s Fu...

Page 14: ...is disactivated Trg Disab Function Disable no recording Start Trigger on time start of protection functions Trip Trigger on trip time delay end of protection functions Ext Inp Trigger from the Digita...

Page 15: ...te Front panel RS232 communication speed Com RBd Remote Baud Rate Rear panel terminal blocks RS485 communication speed Com Mod Remote mode communication parameters Note Any change of this setting beco...

Page 16: ...controlled by the activation of the Digital Input D1 BI Enable in this case the set trip time delay of the function is increased by 2xtBF so that other Protection Relays set with the same trip time d...

Page 17: ...sion Module D1 Digital Input 1 D1 By the interface program MSCom 2 it is possible view the status or via RS485 port Modbus protocol D2 Digital Input 1 D2 D3 Digital Input 1 D3 D4 Digital Input 1 D4 D5...

Page 18: ...lay can be totally managed locally either by the RS232 communication port or by the 4 key buttons and the LCD display or remotely via the communication bus RS485 connected to the rear terminal blocks...

Page 19: ...ped reset takes places by pressing the reset button d Yellow LED PWR I R F Illuminated during normal operation when Power Supply is ON Flashing when a Relay Internal Fault is detected When any protect...

Page 20: ...d the Communication Protocol is MODBUS RTU IEC60870 5 103 The configuration of transmission parameters is selectable Baud Rate 9600 19200 bps 9600 19200 bps 9600 19200 bps Start bit 1 1 1 Data bit 8 8...

Page 21: ...ommunication Port on Front Face Panel This port is used for communication through the Front Face Panel between a local Lap top PC The physical link is RS232 by the standard female 9 pin D sub connecto...

Page 22: ...er measurements to go back to Meas Display Description I 0 65535 In Largest of the 3 phase currents of rated current IA 0 65535 A RMS value of Phase A current Primary Amps IB 0 65535 A RMS value of Ph...

Page 23: ...hich caused the relay tripping For indication of the TRIP Cause the following acronyms are used I 1 st Overcurrent Short Circuit I 2 nd Overcurrent Short Circuit IH 3 rd Overcurrent Short Circuit Io 1...

Page 24: ...YY to set year XX MM to set month XX XX DD to set day XX XX XX hh mm to set hour XX mm to set minutes To validate Set Done Exit 11 5 3 RatedVal Rated Input Values RatedVal 1st Variable to scroll varia...

Page 25: ...shold doubling 0 02 9 99 0 01 IH 3F51 FuncEnab Enable Enable of the protection function Enable Disable Options BI Disable Operation controlled by Blocking Digital Input Enable Disable 2xI Enable Autom...

Page 26: ...le of the protection function Enable Disable Options Trg Trip Trigger operation mode Disable Start Trip Ext Inp TripLev No Parameters Timers tPre 0 30 Recording time before Trigger 0 10 0 50 0 1 tPost...

Page 27: ...e N D N D Normally Deenergized N E Normally Energized N D N E R3 Link Ta I I IH Io Io IoH Association of functions to output relay R3 T Ta I tI I tI IH tIH Io tIo Io tIo tIoH BF RTD IRF HwRec CBopen C...

Page 28: ...scription Clear Erase memory of Trip Counters Event Records Test Starts a relay diagnostic test Reset Reset after trip CBopen Manual Open Close Breaker CBclose Manual Close Close Breaker 11 8 Info Ver...

Page 29: ...MC20 X 10 4 Doc N MO 0352 ING Microener Copyright 2010 FW 720 07 01 Date 09 04 2008 Rev 1 Pag 29 of 35 12 Keyboard Operational Diagram...

Page 30: ...MC20 X 10 4 Doc N MO 0352 ING Microener Copyright 2010 FW 720 07 01 Date 09 04 2008 Rev 1 Pag 30 of 35...

Page 31: ...s modification or to issue a command through the relay itself using the managing software MSCom The user can decide whether inserting his own password see MS Com Operational Manual or keeping the pass...

Page 32: ...C20 X 10 4 Doc N MO 0352 ING Microener Copyright 2010 FW 720 07 01 Date 09 04 2008 Rev 1 Pag 32 of 35 16 Connection Diagram 16 1 UX10 4 Expansion Module Wiring Diagram 10 Digital Inputs 4 Output Relay...

Page 33: ...MC20 X 10 4 Doc N MO 0352 ING Microener Copyright 2010 FW 720 07 01 Date 09 04 2008 Rev 1 Pag 33 of 35 17 Overall Dimensions...

Page 34: ...orizontal position of the screws driver mark Draw out the PCB by pulling on the handle 18 2 Plug In Rotate clockwise the screws in the horizontal position of the screws driver mark Slide in the card o...

Page 35: ...de disturbance 0Hz 150KHz IEC61000 4 16 level 4 Electrical fast transient burst IEC61000 4 4 level 3 2kV 5kHz HF disturbance test with damped oscillatory wave 1MHz burst test IEC60255 22 1 class 3 400...

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