ABB Relion REQ650, Руководство по применению

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6.4 Four step phase overcurrent protection phase
segregated output OC4SPTOC
6.4.1 Identification
Function description IEC 61850 identification IEC 60617 identification ANSI/IEEE C37.2 device
number
Four step phase
overcurrent protection,
phase segregated
output
OC4SPTOC
ID-2147.VSD V1 EN
51/67
6.4.2 Application
The four step phase overcurrent protection phase segregated output OC4SPTOC is
used in several applications in the power system. Some applications are:
• Short circuit protection of feeders in distribution and subtransmission systems.
Normally these feeders have radial structure.
• Back-up short circuit protection of transmission lines.
• Back-up short circuit protection of power transformers.
• Short circuit protection of different kinds of equipment connected to the power
system such as; shunt capacitor banks, shunt reactors, motors and others.
• Back-up short circuit protection of power generators.
If VT inputs are not available or not connected, setting parameter
DirModex (x=step 1, 2, 3 or 4) shall be left to default value,
Nondirectional , or set to Off .
In many applications several steps with different current pick up levels and time
delays are needed. OC4SPTOC can have up to four different, individual settable,
steps. The flexibility of each step of the OC4SPTOC function is great. The following
options are possible:
Non-directional/Directional function: In most applications the non-directional
functionality is used. This is mostly the case when no fault current can be fed from the
protected object itself. In order to achieve both selectivity and fast fault clearance, the
directional function can be necessary.
Power transformers can have a large inrush current, when being energized. This
phenomenon is due to the saturation of the transformer magnetic core during parts of
the period. There is a risk that inrush current will reach the levels above the pick-up
Section 6
1MRK 505 291-UEN A
Current protection
104
Application manual