ABB RELION REF615R, Technical Manual

Page: 157 / 664

The network rotating direction is set in the protection relay using the
parameter in the HMI menu
Configuration/System/Phase rotation . The
default parameter value is "ABC".
V
B
V
C
V
A
V
C
V
B
V
A
NETWORK ROTATION ABC NETWORK ROTATION ACB
V
BC
V
AB
V
CA
V
BC
V
CA
V
AB
I
A
I
B
I
C
I
A
I
B
I
C
GUID-BF32C1D4-ECB5-4E96-A27A-05C637D32C86-ANSI V1 EN
Figure 74: Examples of network rotating direction
4.1.3.7 Application
67/51P and 67/50P is used as short-circuit protection in three-phase distribution or sub
transmission networks operating at 50 or 60 Hz.
In radial networks, phase overcurrent protection relays are often sufficient for the short
circuit protection of lines, transformers and other equipment. The current-time
characteristic should be chosen according to the common practice in the network. It is
recommended to use the same current-time characteristic for all overcurrent protection
relays in the network. This includes the overcurrent protection of transformers and other
equipment.
The phase overcurrent protection can also be used in closed ring systems as short circuit
protection. Because the setting of a phase overcurrent protection system in closed ring
networks can be complicated, a large number of fault current calculations are needed.
There are situations with no possibility to have the selectivity with a protection system
based on overcurrent protection relays in a closed ring system.
In some applications, the possibility of obtaining the selectivity can be improved
significantly if 67/51P and 67/50P is used. This can also be done in the closed ring
networks and radial networks with the generation connected to the remote in the system
thus giving fault current infeed in reverse direction. Directional overcurrent protection
1MRS240050-IB C
Section 4
Protection functions
REF615R 151
Technical Manual