Thytronic DMC3S - Ground Directional Overcurrent - 67 N (Intermittent Faults)

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DMC3S - Manual - 08 - 2021
• Third threshold IED>>> by the start of the fourth threshold IED>>>> with the Deactivation IED>>>
by start IED>>>> parameter (IED>>>disIED>>>>) in the menu Set \ Protections \ Ground
directional overcurrent - 67N \ Threshold IED67N.Sb \ Parameters.
A constant reset time can be set for each threshold (tED>RES, tED>>aRES, tED>>bRES, tED>>>RES,
tED67N.SbRES).
Shrink time
For each of the thresholds programmed with definite time characteristic, you can select contracted
time by setting to ON the parameter EnTcIED>def, EnTcIED>>adef, EnTcIED>>bdef,
EnTcIED>>>def and EnTcIEDSbdef, and regulating the contracted time (tcIED>def ,
tcIED>>adef, tcIED>>bdef, tcIED>>>def and tcIEDSbdef) and operating time (tat-
cIED>def, tatcIED>>adef, tatcIED>>bdef , tatcIED>>>def and tatcIEDSbdef).
Once the breaker closes, during the operating time (e.g.: tatcIPE>def), the value of the trip time
(e.g.: tED>def ) is replaced by the contracted time (e.g.: tcIED>def ); when the operating time
expires the trip time is reset (e.g.: tED>def ).
The parameters are available in the menu Set \ Protections \ Ground directional overcurrent
- 67N \ Threshold IED> (Threshold IED>>a, Threshold IED>>b, Threshold IED>>>,Threshold
67N.Sb) \ Definite time.
Second harmonic restraint
For each threshold, a second harmonic restraint block can be set by setting to ON the param-
eter IED>2ndh-REST, IED>>a2ndh-REST, IED>>b2ndh-REST, IED>>>2ndh-
REST, 67N.Sb2ndh-REST.
The parameters are available in the menu Set \ Protections \ Ground directional overcurrent - 67N
\ Threshold IED> (Threshold IED>>a, Threshold IED>>b, Threshold IED>>>,Threshold 67N.Sb) \ Pa-
rameters.
Functional block (Block3)
If the voltmetric measurement chain fails (function 74VT tripped) or amperometric measurement
chain fails (function 74CT tripped), all thresholds of protection 67N are blocked.
— Ground directional overcurrent - 67N (Intermittent faults)
Preface
The maximum directional ground current protection function IED>>>> detects intermittent “Arcing
ground” faults
Detection is done by protection function 67N logically controlling the start statuses, by starting a
specific 59N threshold or by receiving the Goose IEC61850 for the state of start by residual overvolt-
age of the protection DV7500.
The logic of threshold IED>>>> is shown in the following figure:
char-F67N-intermittenti.ai
tED>>>>RRIC59N
IED>>>>-UE>
T
R
0
tED>>>>
T0
tED>>>>RRIC59N
tED>>>>RRIC67N
tED>>>>Inb
tED>>>>
T0
tED>>>>RRIC67N
tED>>>>1s
tED>>>>1s
Start UE>Ext
≥1
≥1
&
(ON Enable)
IED>>>>-IED>Av Enable
Start IED>
&
(ON Enable)
IED>>>>-IED>>a_Av Enable
Start IED>>a
Start IED>>b
&
(ON Enable)
IED>>>>-IED>>b_Av Enable
&
(ON Enable)
In dig.(61850)
TripIED>>>>
IED>>>>-UeExt_Av Enable
&
&
T
R
0
tED>>>>Inb
UE
&
State
UE ≥IED>>>>-UE>
Functional diagram of the threshold of the directional ground protection against intermittent faults (67N)