ABB RET615 - Page 38

Table 34. Negative phase-sequence overcurrent protection (NSPTOC)
Characteristic Value
Operation accuracy Depending on the frequency of the current measured: f
n
±2 Hz
±1.5% of the set value or ±0.002 x I
n
Start time
1)2)
Minimum Typical Maximum
I
Fault
= 2 x set Start value
I
Fault
= 10 x set Start value
22 ms
14 ms
24 ms
16 ms
25 ms
17 ms
Reset time < 40 ms
Reset ratio Typical 0.96
Retardation time < 35 ms
Operate time accuracy in definite time mode ±1.0% of the set value or ±20 ms
Operate time accuracy in inverse time mode
±5.0% of the theoretical value or ±20 ms
3)
Suppression of harmonics DFT: -50 dB at f = n x f
n
, where n = 2, 3, 4, 5,…
1) Negative sequence current before fault = 0.0, f
n
= 50 Hz, results based on statistical distribution of 1000 measurements
2) Includes the delay of the signal output contact
3) Maximum Start value = 2.5 x I
n
, Start value multiples in range of 1.5 to 20
Table 35. Negative phase-sequence overcurrent protection (NSPTOC) main settings
Parameter
Function Value (Range) Step
Start value NSPTOC 0.01...5.00 x I
n
0.01
Time multiplier NSPTOC 0.05...15.00 0.01
Operate delay time NSPTOC 40...200000 ms 10
Operating curve type
1)
NSPTOC Definite or inverse time
Curve type: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
17, 18, 19
1) For further reference please refer to the Operating characteristics table
Transformer Protection and Control 1MRS756891 F
RET615
Product version: 4.0
38 ABB