ABB REG670 - Negativ Sequence Time Overcurrent Protection for Machines NS2 PTOC

The value of k=0.92 is recommended in generator applications as the trip delay is
normally quite long.
The calibration factors for current and voltage measurement errors are set % of rated
current/voltage:
IAmpComp5, IAmpComp30, IAmpComp100
UAmpComp5, UAmpComp30, UAmpComp100
IAngComp5, IAngComp30, IAngComp100
The angle compensation is given as difference between current and voltage angle
errors.
The values are given for operating points 5, 30 and 100% of rated current/voltage. The
values should be available from instrument transformer test protocols.
9.12 Negativ sequence time overcurrent protection for
machines NS2PTOC
9.12.1 Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Negative sequence time overcurrent
protection for machines
NS2PTOC 2I2> 46I2
9.12.2 Application
Negative sequence overcurrent protection for machines NS2PTOC is intended
primarily for the protection of generators against possible overheating of the rotor
caused by negative sequence component 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 can also be used as a backup protection, that is, to protect the generator in
the event line protections or circuit breakers fail to perform for unbalanced system
faults.
1MRK 502 071-UEN - Section 9
Current protection
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062 387
Application manual