In simple words this means that the CB is not breaking the current at the first zero
crossing after separation of the CB contacts. Instead current is re-ignited and only
braked at consecutive current zero crossings. This condition is manifested as high
current pulses at the moment of current re-ignition.
To detect this CB condition, the built in overcurrent feature can be used. Simply, any
start of the overcurrent feature during breaker normal opening means a restrike.
Therefore simple logic can be created in the Application Configuration tool to detect
such CB behavior. Such CB condition can be just alarmed, and if required, the built in
disturbance recorder can also be triggered.
To create this logic, a binary signal that the CB is going to be opened (but not trip
command) shall be made available to the IED.
9.16
Negativ sequence time overcurrent protection for
machines NS2PTOC (46I2)
GUID-25821361-229A-44BB-A60F-FC6DD9F4F140 v2
9.16.1
Identification
GUID-19BB1653-55AE-44D1-B964-F59AED5350C4 v3
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Negative sequence time overcurrent
protection for machines
NS2PTOC
2I2>
46I2
9.16.2
Application
GUID-66CBDF76-B548-478F-8D59-CBAC4F6C1F85 v1
GUID-ED2E176E-BE14-45C2-875F-369E1F27BC29 v1
Negative sequence overcurrent protection for machines NS2PTOC (46I2) 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 (46I2) 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.
Section 9
1MRK 504 163-UUS A
Current protection
600
Transformer protection RET670 2.2 ANSI
Application manual
Содержание RELION RET670
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