GE T60, Instruction Manual

Page: 535 / 796

GE Multilin T60 Transformer Protection System 7-13
7 COMMANDS AND TARGETS 7.1 COMMANDS
7
Process Bus Failure Major Self-test
Description: Mission critical data is not available via the process bus. An AC quantity is considered critical if both AC bank
origins and the crosschecking settings are other than none. This self-test is also initiated by an AC input discrepancy being
detected. See the description of the crosschecking setting in this manual for further information. In addition, this self-test
can be initiated by user logic responding to loss of critical contact input/output or other data using the
Process Bus Failure
Operand user-programmable self-test setting. This setting is located in the Settings > Product Setup > User-Program-
mable Self Test menu.
Severity: Protection is not available and all contact outputs and shared outputs are de-asserted.
If this message appears, first rectify any Process Bus Trouble and Brick Trouble self-test errors. Check the actual value of
the operand referenced by the
Process Bus Failure Operand setting, and if “On”, determine the cause and rectify.
Should the problem persist with the foregoing all clear, the cause must be an AC input discrepancy, which is typically the
result of problems in the input signals to the Bricks, or faults in the Brick input conditioning hardware. If the error was
annunciated the first time significant signal was encountered, suspect the former cause and check the copper connections
external to the Brick. Where multiple UR-series devices have self-test errors, look for common causes.
To further isolate AC input discrepancy errors, put the relay in test-isolated mode, then one by one, temporally change an
AC 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 with
a single origin.
Process Bus Trouble Minor Self-Test
Description: 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 failure
to 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 are
being 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 being
received. 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 the
affected Brick. If the problem continues after cleaning, consult the factory.
Brick Trouble Minor Self-Test
Description: 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/outputs
may 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. If
the ambient temperature and supply voltage are within Brick specifications, consult the factory. Troubles resulting from a
Brick output failing to respond to an output command can only be detected while the command is active, and so in this case
the 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.