8.4.4.2 PHASE SEQUENCE TEST (“SEQ TEST”)
The phase sequence test determines if Phase A Current Leads Phase B current by 120 degrees and Phase B
Current Leads Phase C current by 120 degrees and finally that Phase C current leads Phase A current by 120
degrees. The possibility that the phases are connected in sequence but are rotated in some way is addressed
by the Differential Current test.
One amp of current should be present on each phase for the relays to enter startup mode. If not already in
Startup Mode, enter Startup Mode following the detailed step by step instructions above, or see Section 6.
STEP 1.
The first test that is run in STARTUP MODE is the Phase Sequence test. As soon as either station in a two ter-
minal system or any of the three stations in a three terminal system is placed in STARTUP MODE, all the units
will respond by entering Startup Mode. This will occur whether or not there is an operator using the display at
the remote station(s). If the remote station has an operator displaying values in Read Mode or Program Mode, it
may not be apparent that the system has entered Startup Mode and the unit will not display the Phase Se-
quence Test.
All the units will immediately begin running the phase sequence test and display the following:
--------------- ---------------
SEQ TEST SEQ TEST
LI 1I 2I LI 1I
--------------- ---------------
( Three terminal ) ( Two terminal )
The letter ‘L’ indicates the local station, “1” indicates remote station one, and ” 2” indicates remote station two.
Each station identification is followed by either and ‘I” for invalid, a “P” for pass or a “F” for fail.
Each relay runs the phase sequence test and transmits the results to the other stations.
The display will show a valid result after about ten seconds. The unit should show all units passing this test for
at least ten seconds, before continuing to the next step of the Startup Mode procedure.
STEP 2.
At this point the user should shunt phase A current as shown in Figure 8-5. Even though the 3I0 phase control-
ler senses the change in current, the Phase Sequence Test will continue to show pass on all stations if the 3I0
controller is phased properly. Note that the 3I0 fault detector LED may light at this time and that this is not a
problem.
STEP 3.
The user should now remove the shunt from PHASE A current.
NOTE
ALL THREE UNITS IN A THREE TERMINAL SYSTEM SHOULD PASS THE PHASE SEQUENCE
TEST BEFORE CONTINUING TO THE NEXT STEP IN THE COMMISSIONING PROCEDURE
RFL 9300 RFL Electronics Inc.
October 20, 2004 8 - 26 (973) 334-3100
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