
Manual MRI3 GB
Woodward
DOK-TD-MRI3 Rev.A
3
Contents
1.
Introduction and application ....................................................................... 5
2.
Features and characteristics ...................................................................... 6
3.
Design ........................................................................................................... 7
3.1
Connections ........................................................................................................................ 7
3.1.1
Analog input circuits ........................................................................................................ 9
3.1.2
Output relays ................................................................................................................... 9
3.1.3
Blocking input ................................................................................................................ 10
3.1.4
External reset input ....................................................................................................... 10
3.2
Relay output contacts ........................................................................................................ 10
3.2.1
Fault recorder ................................................................................................................ 11
3.2.2
Parameter settings (see chapter 5) ............................................................................... 12
3.3
LEDs .................................................................................................................................. 17
4.
Working principle ....................................................................................... 18
4.1
Analog circuits ................................................................................................................... 18
4.2
Digital circuits .................................................................................................................... 18
4.3
Directional feature ............................................................................................................. 19
4.3.1
Reversal in direction during the activation phase ......................................................... 19
4.4
Earth fault protection ......................................................................................................... 23
4.4.1
Generator stator earth fault protection .......................................................................... 23
4.4.2
System earth fault protection ........................................................................................ 23
4.5
Earth-fault directional feature (ER/XR-relay type) ............................................................. 24
4.6
Determining earth short-circuit fault direction (SR/YR-relay type) ................................. 26
4.6.1
Directly – earthed system .............................................................................................. 26
4.6.2
Resistance – earthed system ........................................................................................ 27
4.6.3
Connection possibilities of the voltage transformers for SR relay types ....................... 28
4.7
Demand imposed on the main current transformers ......................................................... 28
5.
Operation and settings .............................................................................. 29
5.1
Display ............................................................................................................................... 29
5.2
Setting procedure .............................................................................................................. 30
5.3
System parameter ............................................................................................................. 31
5.3.1
Display of measuring values as primary quantities (I
prim
phase) ................................... 31
5.3.2
Display of earth current as primary quantity (I
prim
earth) ............................................... 31
5.3.3
Display of residual voltage U
E
as primary quantity (U
prim
/U
sec
) ..................................... 31
5.3.4
Voltage transformer connection for residual voltage measuring (3pha/e-n/1:1) ........... 31
5.3.5
Nominal frequency ........................................................................................................ 31
5.3.6
Display of the activation storage (FLSH/NOFL) ............................................................ 32
5.3.7
Parameter switch/external triggering of the fault recorder ............................................ 32
5.4
Parameter protection ......................................................................................................... 33
5.4.1
Pickup current for phase overcurrent element (I>) ....................................................... 33
5.4.2
Time current characteristics for phase overcurrent element (CHAR I>) ....................... 33
5.4.3
Trip delay or time factor for phase overcurrent element (tI>) ........................................ 33
5.4.4
Reset setting for all tripping characteristics in the phase current path ......................... 34
5.4.5
Current setting for high set element (I>>) ..................................................................... 34
5.4.6
Trip delay for high set element (tI>>) ............................................................................ 34
5.4.7
Relay characteristic angle RCA .................................................................................... 34
5.4.8
Pickup value for residual voltage UE (ER/XR-relay type) ............................................. 34
5.4.9
Pickup current for earth fault element (IE>) .................................................................. 34
5.4.10
WARN/TRIP changeover (all earth fault-relay type) ................................................. 35
5.4.11
Time current characteristics for earth fault element (CHAR I
E
) (not for ER/XR-relay
type) 35
5.4.12
Trip delay or time multiplier for earth fault element (t
IE>>
) ......................................... 35
5.4.13
Reset mode for inverse time tripping in earth current path ....................................... 35
5.4.14
Current setting for high set element of earth fault supervision (I
E>>
) ......................... 35
5.4.15
Trip delay for high set element of earth fault supervision (t
IE>>
) ................................ 35
5.4.16
COS/SIN Measurement (ER/XR-relay type) ............................................................. 35
5.4.17
SOLI/RESI changeover (SR/YR-relay type) ............................................................. 36
5.4.18
Block/Trip – time ........................................................................................................ 36