7-12 D60 Line Distance Protection System GE Multilin7.2 TARGETS 7 COMMANDS AND TARGETS7To further isolate AC input discrepancy errors, put the relay in test-isolated mode, then one by one, temporally change anAC bank crosschecking setting to none, until the Process Bus Failure clears. Once the problem AC bank has been identi-fied, the values from each of the two Bricks can be examined individually by temporarily mapping each to an AC bank witha single origin.Process Bus Trouble Minor Self-TestDescription: Communications problems with one or more Bricks. The text of the message identifies the affected field units.This self-test is initiated by low received signal levels at either the Brick or Process Card end, and by the sustained failureto receive poll responses from the proper Brick.Severity: This self-test error does not directly inhibit protection. However, the affected Brick inputs/outputs may not be avail-able to the UR-series device.If this message appears, check the field unit actual values. An indication of equipment mismatch means that messages arebeing received from a Brick, but there is a discrepancy between the settings and the actual Brick serial number, order code,and/or core number. Check that the correct core on the correct Brick is patched through to the correct Process Card port,and that the field unit settings are correct. An indication of communications loss means that no messages are beingreceived. Check that the patching is correct, and that the Brick has power. If that is not the problem, use a professional opti-cal fiber connector cleaning kit to clean both sides of all optical fiber connections from the Process Card through to theaffected Brick. If the problem continues after cleaning, consult the factory.Brick Trouble Minor Self-TestDescription: Brick internal self-testing has detected a trouble internal to the Brick.Severity: This self-test error does not directly inhibit protection. However, some or all of the affected Brick inputs/outputsmay not be available to the UR-series device.If this message appears, check the Brick environment for over/under temperatures and the voltage of its power source. Ifthe ambient temperature and supply voltage are within Brick specifications, consult the factory. Troubles resulting from aBrick output failing to respond to an output command can only be detected while the command is active, and so in this casethe target is latched. A latched target can be unlatched by pressing the faceplate reset key if the command has ended,however the output may still be non-functional.f)
