Thytronic NC20 - RMS Phase Overcurrent - 50;51

19
NC2 0 - Manual - 01 - 2015
TECHNICAL DATA
RMS Phase overcurrent - 50/51
[1]
I>AL element
I
CLP>AL
Activation time (t
CLP>AL
) 0.00...100.0 s
0.00...9.99 s (step 0.01 s)
10.0...100.0 s (step 0.1 s)
Defi nite time
50/51 Alarm threshold defi nite time (I>
ALdef
) 0.100...10.00 I
n
0.100...0.999 I
n
(step 0.001 I
n
)
1.00...10.00 I
n
(step 0.01 I
n
)
I>
ALdef
within CLP (I
CLP
>
ALdef
) 0.100...10.00 I
n
0.100...0.999 I
n
(step 0.001 I
n
)
1.00...10.00 I
n
(step 0.01 I
n
)
I>
ALdef
Operate time (t>
ALdef
) 0.03...200 s
0.03...9.99 s (step 0.01 s)
10.0...99.9 s (step 0.1 s)
100...200 s (step 1 s)
I> Element
I> Curve type (I>
Curve
) DEFINITE
IEC/BS A, B, C
ANSI/IEEE MI, VI, EI
CAPACITOR
I
CLP
> Activation time (t
CLP>
) 0.00...100.0 s
0.00...9.99 s (step 0.01 s)
10.0...100.0 s (step 0.1 s)
I> Reset time delay (t>
RES
) 0.00...100.0 s
0.00...9.99 s (step 0.01 s)
10.0...100.0 s (step 0.1 s)
Defi nite time
50/51 First threshold defi nite time (I>
def
) 0.100...10.00 I
n
0.100...0.999 I
n
(step 0.001 I
n
)
1.00...10.00 I
n
(step 0.01 I
n
)
I>
def
within CLP (I
CLP>def
) 0.100...10.00 I
n
0.100...0.999 I
n
(step 0.001 I
n
)
1.00...10.00 I
n
(step 0.01 I
n
)
I>
def
Operating time (t>
def
) 0.03...200.00 s
0.03...9.99 s (step 0.01 s)
10.0...99.9 s (step 0.1 s)
100...200 s (step 1 s)
Inverse time
[2]
50/51 First threshold inverse time (I>
inv
) 0.100...10.00 I
n
0.100...0.999 I
n
(step 0.001 I
n
)
1.00...10.00 I
n
(step 0.01 I
n
)
I>
inv
within CLP (I
CLP>inv
) 0.100...10.00 I
n
0.100...0.999 I
n
(step 0.001 I
n
)
1.00...10.00 I
n
(step 0.01 I
n
)
I>
inv
Operating time (t>
inv
) 0.02...60.0 s
0.02...9.99 s (step 0.01 s)
10.0...60.0 s (step 0.1 s)
Pickup time ≤ 0.03 s
Dropout ratio 0.95...0.98
Dropout time ≤ 0.05 s
Overshoot time 0.03 s
Pickup accuracy ± 0.5% with 0.1 I
n
, ± 0.2% with 1 I
n
Operate time accuracy 5% or ± 10 ms
Note 1 The RMS 50/51 protection is based on RMS value measurement of three phase currents (the computed RMS value takes into account the con-
tribution of fundamental and harmonic up to eleventh order).
Note 2
Standard Inverse Time (IEC 255-3/BS142 type A or SIT): t = 0.14 · t>
inv
/ [(I
RMS
/I>
inv
)
0.02
- 1]
Very Inverse Time (IEC 255-3/BS142 type B or VIT): t = 13.5 · t>
inv
/ [(I
RMS
/I>
inv
) - 1]
Extremely Inverse Time (IEC 255-3/BS142 type C or EIT): t = 80 · t>
inv
/ [(I
RMS
/I>
inv
)
2
- 1]
Moderately Inverse (ANSI/IEEE type MI): t = t>
inv
· {0.01 / [(I
RMS
/I>
inv
)
0.02
- 1] + 0.023}
Very Inverse (ANSI/IEEE type VI): t = t>
inv
· {3.922 / [(I
RMS
/I>
inv
)
2
- 1] + 0.098}
Extremely Inverse (ANSI/IEEE type EI): t = t>
inv
· {5.64 / [(I
RMS
/I>
inv
)
2
- 1] + 0.024}
CAPACITOR: t = t>
inv
· {50000 / [1.1 · (I
RMS
/I>
inv
)
17
- 1]} + 0.1
I
RMS
: RMS input current
t: operate time
I>
inv
: threshold setting
t>
inv
: operate time setting
Asymptotic reference value: 1.1 I>
inv
Minimum operate time: 0.1 s
Equation is valid for 1.1 ≤ I
RMS
/I>
inv
≤ 20
With I>
inv
pickup ≥ 2.5 I
n
, the upper limit is 50 I
n
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