ABB Relion 670 Series Applications Manual page 144

Bay control, version 2.1 ansi
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Section 7
Current protection
Table 16:
Curve name
ANSI Extremely Inverse
ANSI Very Inverse
ANSI Normal Inverse
ANSI Moderately Inverse
ANSI/IEEE Definite time
ANSI Long Time Extremely Inverse
ANSI Long Time Very Inverse
ANSI Long Time Inverse
IEC Normal Inverse
IEC Very Inverse
IEC Inverse
IEC Extremely Inverse
IEC Short Time Inverse
IEC Long Time Inverse
IEC Definite Time
User Programmable
ASEA RI
RXIDG (logarithmic)
It is also possible to tailor make the inverse time characteristic.
Normally it is required that EF4PTOC (51N_67N) shall reset as fast as possible when the current
level gets lower than the operation level. In some cases some sort of delayed reset is required.
Therefore different kinds of reset characteristics can be used.
For some protection applications there can be a need to change the current pickup level for some
time. Therefore there is a possibility to give a setting of a multiplication factor
residual current pick-up level. This multiplication factor is activated from a binary input signal
MULTPUx to the function.
Power transformers can have a large inrush current, when being energized. This inrush current can
have residual current components. The phenomenon is due to saturation of the transformer
magnetic core during parts of the cycle. There is a risk that inrush current will give a residual
current that reaches level above the pickup current of the residual overcurrent protection. The
inrush current has a large second harmonic content. This can be used to avoid unwanted
operation of the protection. Therefore, EF4PTOC (51N_67N) has a possibility of second harmonic
restrain
of the fundamental current.
138
Time characteristics
2ndHarmStab if the level of this harmonic current reaches a value above a set percentage
1MRK 511 358-UUS A
INxMult to the
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