49
DMC3S - Manual - 08 - 2021
Shrink time
For each of the programmed thresholds with definite time characteristic you can set the contracted
time by setting to
ON
the parameter
EnTcINe>def
,
EnTcINe>>def
and regulating the con-
tracted time (
tcINe>def,
tcINe>>def
) and operating time (
tatcINe>def,
tatcINe>>def
).
Once the breaker closes, during the operating time (e.g.:
tatcINe>def
), the value of the trip time
(e.g.:
tNe>def
) is replaced by the contracted time (e.g.:
tcINe>def
); when the operating time
expires the trip time is reset (e.g.:
tNe>def
).
The related parameters are available in the menu
Set \ Protections \ Neutral overcurrent - 51N(E) \
Threshold INe>
(
Threshold INe>>) \ Definite time
.
Second harmonic restraint
For each of the thresholds (
I
Ne
>,
I
Ne
>>) you can set a second harmonic restraint block by setting to
ON
the parameter
INe>2ndh-REST, INe>>2ndh-REST
.
The related parameters are available in the menu
Set \ Configuration parameters A(or B) \ Neutral
overcurrent - 51N(E) \
Threshold INe>
(
Threshold INe>>) \ Parameters
.
Fun_50N-51N(E).ai
t
Ne>RES
T
0
RESET
t
Ne>
0
T
≥
1
t
Ne>inv
t
Ne>RES
Start INe>
Trip INe>
Start
I
2ndh>
ON
≡
Inhibit
(from INe>> element)
ON
≡
Enable IE> residual overcurrent element
INe> inhibition
Block1, Block2
&
&
2nd harmonic restraint enable (ON
≡
Enable)
INe>2ndh-REST
TR
IP
PI
NG M
AT
RI
X
(LE
D+R
EL
AY
S)
I
Ne
> Curve
0
T
INe> Enable
I
Ne
>TR-K
I
Ne
>TR-L
I
Ne
>ST-L
I
Ne
>ST-K
I
E
≥
1
&
State
I
Ne
>
inv
I
E
≥
I
Ne
>
def
I
E
≥
I
Ne
>
inv
I
Ne
>
def
&
State
&
EnTcINe>def
t
Ne>def
t
CINe>def
t
atcIE
>
def
t
atcINe
>
def
CB control
0 =
t
E>def
1 =
t
CIE>def
“0”
“1”
CB control
tatcINe>def
tcINe>def
tNe>def
tNe>def
BREAKER OPEN
Breaker state
Shrink time enable
Threshold timer
t
BREAKER CLOSED
OFF
Shrink time trip
ON
Functional diagram of the first threshold of the neutral overcurrent function 51N(E)
