Negative-Sequence Time Overcurrent Protection For Machines Ns2Ptoc (46I2) - ABB Relion Technical Manual

1MRK 502 048-UUS A
8.9
8.9.1
8.9.2
Technical manual
Function
Impulse margin time,
overcurrent
Operate value,
undervoltage
Critical impulse time,
undervoltage
Impulse margin time,
undervoltage
Operate value,
overvoltage
Timers
Negative-sequence time overcurrent protection for
machines NS2PTOC (46I2)
Identification
Function description
Negative sequence time overcurrent
protection for machines
Functionality
Negative-sequence time overcurrent protection for machines NS2PTOC (46I2) is
intended primarily for the protection of generators against possible overheating of the
rotor caused by negative sequence current in the stator current.
The negative sequence currents in a generator may, among others, be caused by:
• Unbalanced loads
• Line to line faults
• Line to ground faults
• Broken conductors
• Malfunction of one or more poles of a circuit breaker or a disconnector
NS2PTOC (46I2) can also be used as a backup protection, that is, to protect the generator
in case line protections or circuit breakers fail to clear unbalanced system faults.
Range or value
15 ms typically
(2-150)% of VBase
10 ms typically at 2 to 0 x V
set
15 ms typically
(2-200)% of VBase
(0.000-60.000) s
IEC 61850
identification
NS2PTOC
Section 8
Current protection
Accuracy
-
± 0.5% of V at V<V
n
± 0.5% of V at V>V
-
-
± 0.5% of V at V<V
n
± 0.5% of V at V>V
± 0.5% ± 25 ms
IEC 60617 ANSI/IEEE C37.2
identification device number
2I2> 46I2
n
n
n
n
265