RFL 9300 RFL Electronics Inc.
October 20, 2004 7 - 9 (973) 334-3100
The display has a resolution of 0.25 amperes, and is accurate to +
0.125 amperes. The
minimum display reading is 0.5 amperes.
The display ac current readings and settings are in terms of rms amperes. However, the
RFL 9300 does not measure current. Instead, it measures "charge," or the area under
the half-cycle current wave. For display purposes, the RFL 9300 converts charge to ac
rms current (assuming a perfect, symmetrical, 60-Hz sine wave). All references to "cur-
rent" in this procedure are really "charge, as converted to current."
3. Gradually increase the ac test current.
At 0.5 amperes, the fault detector in the 93B PC module monitoring 3I
0
(ground) will
pick up, and its FD indicator will light. At 6 amperes, the fault detector in the 93B PC
module monitoring Phase A will pick up, and its FD indicator will light.
4. Gradually reduce the AC test current to zero. Suddenly change the test current by at least 1 ampere.
The phase fault detectors will operate momentarily, and their FD indicators will flash. A
pulse-stretching timer keeps these signals active for 75 ms.
5. Apply any test current, suddenly or gradually.
The RFL 9300s will not trip. The test current may contain a dc offset or harmonics.
These waveforms will not cause instability during external fault testing.
7.4.4 OTHER EXTERNAL FAULT TYPES (optional)
1. The other phase-to-ground external faults (B-G and C-G) may be tested by reconnecting the circuit
shown in Figure 7-2 to energize Phase B or Phase C instead of Phase A.
2. Phase-to-phase external faults also may be simulated. For example, an A-B external fault may be
simulated by connecting the current source as shown in Figure 7-3.
3. Three-phase external faults may be simulated by connecting the equipment as shown in Figure 7-4.
The test setup in Figure 7-4 creates the phasor relationship shown in Figure 7-5. An ex-
ternal three-phase fault actually has the phasor relationship shown in Figure 7-6.
Currents I
B
and I
C
are in-phase for the test simulation, while these currents are 120 de-
grees out of phase for a real three-phase fault. This difference does not affect the valid-
ity of the single-phase test method. The RFL 9300 is a per-phase (or "segregated
phase") relay. Each phase current (and residual current) is compared end-to-end, with-
out regard to what is happening on the other phases (or residual). This means that the
simplified phasors shown in Figure 7-5 can be used to simulate the real-world phasors
shown in Figure 7-6.
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