ABB RET650 Technical Manual page 156

Section 8
Current protection
150
IEC09000636 V1 EN
Figure 65: Directional characteristic of the phase overcurrent protection
1 RCA = Relay characteristic angle 55°
2 ROA = Relay operating angle 80°
3 Reverse
4 Forward
If no blockings are given the start signals will start the timers of the step. The time
characteristic for step 1 and 4 can be chosen as definite time delay or inverse time
characteristic. Step 2 and 3 are always definite time delayed. A wide range of
standardized inverse time characteristics is available. The possibilities for inverse
time characteristics are described in section
All four steps in OC4PTOC can be blocked from the binary input BLOCK. The binary
input BLKSTx (x=1, 2, 3 or 4) blocks the operation of respective step.
3
1
2
2
4
I
dir
"Inverse time
1MRK 504 135-UEN A
U
ref
IEC09000636_1_vsd
characteristics".
Technical manual