CYG PRS-7367 - Faulty Phase Selection (FPS)

Protection Functions
212 PRS-7367
3.45.1.1 Function Block
FPS
FPS_SelA
FPS_SelB
FPS_SelC
I3p
U3p
FPS_SelMP
FPS_SelSP
Figure 3.45-1 Function block
3.45.1.2 Signals
Table 3.45-1 FPS Input Signals
NO.
Signal
Description
1
I3p
The voltage in all the three phases
2
U3p
The current magnitude in all the three phases
Table 3.45-2 FPS Output Signals
NO.
Signal
Description
1
FPS_SelA
Faulty phase selection result of phase A
2
FPS_SelB
Faulty phase selection result of phase B
3
FPS_SelC
Faulty phase selection result of phase C
4
FPS_SelMP
Faulty phase selection result of multi-phase
5
FPS_SelSP
Faulty phase selection result of single phase
3.45.2 Operation Principle
3.45.2.1 I0 and I2A Selection Element
The phase selection algorithm uses the angle relation between I0 and I2A of the device. There are
three faulty phase selection regions.
Depended on the phase relation between I0 and I2A, the faulty phase can be determined.
1. -60º<Arg(I0/I2A)<60º, region A is selected, possible faulty phase is phase A or phase BC.
2. 60º<Arg(I0/I2A)<180º, region B is selected, possible faulty phase is phase B or phase CA.
3. 180º<Arg(I0/I2A)<300º, region C is selected, possible faulty phase is phase C or phase AB.
For single-phase earth fault, I0 and I2 of faulty phase are in-phase. Earth fault start up zero
sequence current can be set by setting LNP_ResCur_Str.
For phase-to-phase earth fault, I0 and I2 of non-faulty phase are in-phase.
In order to properly expand the ability of grounding distance relay to measure transition resistance,