ABB RET615 Product Manual page 30

Transformer Protection and Control
RET615
Product version: 2.0
Table 28. Negative phase-sequence overcurrent protection (NSPTOC)
Characteristic
Operation accuracy
1)2)
Start time
Reset time
Reset ratio
Retardation time
Operate time accuracy in definite time mode
Operate time accuracy in inverse time mode
Suppression of harmonics
1) Negative sequence current before fault = 0.0, f
measurements
2) Includes the delay of the signal output contact
3) Maximum Start value = 2.5 x I
Table 29. Negative phase-sequence overcurrent protection (NSPTOC) main settings
Parameter
Start value
Time multiplier
Operate delay time
Operating curve
1)
type
1) For further reference please refer to the Operating characteristics table at the end of the Technical data chapter
30
I = 2 x set Start
Fault
value
I = 10 x set Start
Fault
value
= 50 Hz, results based on statistical distribution of 1000
n
, Start value multiples in range of 1.5 to 20
n
Function
NSPTOC
NSPTOC
NSPTOC
NSPTOC
Value
Depending on the frequency of the current
measured: f ±2Hz
n
±1.5% of the set value or ±0.002 x I
Minimum Typical
22 ms 24 ms
14 ms 16 ms
< 40 ms
Typical 0.96
< 35 ms
±1.0% of the set value or ±20 ms
±5.0% of the theoretical value or ±20 ms
DFT: -50dB at f = n x f
n
...
Value (Range)
0.01...5.00 x I
n
0.05...15.00
40...200000 ms
Definite or inverse time
Curve type: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 17, 18, 19
1MRS756891 B
Issued: 01.10.2009
n
Maximum
25 ms
17 ms
3)
, where n = 2, 3, 4, 5,
Step
0.01
0.05
10
ABB