RFL 9300 RFL Electronics Inc.
October 20, 2004 7 - 18 (973) 334-3100
2. Gradually increase the test current at the left terminal.
The 93B PC module monitoring 3I
0
will pick up its overcurrent fault detector at
0.5amperes.
At 3 amperes, the ground WFT logic is satisfied at the right terminal (less than 1.5 am-
peres local current and a received current of 1.5 amperes plus 1.5 amperes of bias).
However, no tripping occurs because only one fault detector (G at the RFL 9300 at the
left terminal) has operated.
The LCCT alarm does not
occur, since this alarm is operated only by Strong Feed Trip
conditions.
3. Apply the 3-ampere test current suddenly at the left terminal.
All red FD indicators on the 93B PC module will flash momentarily, allowing the RFL
9300 at the left terminal to trip on the received WFT message. The RFL 9300 at the left
terminal then sends "Charge Comparison Trip - Ultimate" (CCT-U) signals to the right
RFL 9300, causing it to trip. The TRIP 1 and G target indicators at both relays will light.
4. Return both test currents to zero, and reset the targets on both relays by pressing the RESET
switches. Once the relays are reset, gradually increase the test current at the left terminal after return-
ing the current at the right terminal to ¼ Arms.
At 4.5 amperes, the Phase A WFT logic at the right RFL 9300 is satisfied (1.5 amperes
plus 3 amperes phase bias). Once again, there is no tripping because the fault detector
requirement has not been satisfied.
5. Return both test currents to zero, and apply the 4.5-ampere test current suddenly at the left terminal.
All fault detectors in the 93B PC module will now flash momentarily, and both relays
will trip. The TRIP 1, A, and G target indicators on both relays will light.
6. Return both test currents to zero, and reset the targets on both relays by pressing the RESET
switches. Once the relays are reset, gradually increase the test current at the left terminal.
At 6 amperes, the Phase A fault detector will pick up (continually), and both relays will
trip. The TRIP 1, and A and G target indicators on both relays will light.
7.4.10 OTHER WEAK-FEED INTERNAL FAULT TYPES (optional)
The test circuit shown in Figure 7-10 may be modified to simulate the other types of weak-feed internal faults.
Results for B-G and C-G faults should be similar to those described for A-G faults.
To Next Page