13-42
Testing and Troubleshooting
Date Code 20011205
SEL-311A Instruction Manual
Note:
As you perform this test, other protection elements may assert, causing the relay to
close other output contacts and assert relay targets. This is normal and is not a cause
for concern.
T
ROUBLESHOOTING
T
EST
R
ESULTS
The following information is intended to help you troubleshoot relay tests if the relay does not
perform as you expected.
Symptom:
What to check:
Incorrect Targets
·
Check the relay event report. Determine the asserted elements at
the instant the TRIP output was asserted.
·
Verify the ac connections by plotting currents and voltages from
event report data.
·
Verify the TR, TRCOMM, and TRSOTF settings to ensure the
appropriate elements are enabled to trip.
·
Verify the ULTR setting. If a trip occurs and does not unlatch
following clearance of the fault, new faults do not generate new
targets. You may need to turn off ac current applied to the relay,
deassert 52A inputs, or press the Target Reset button.
Incorrect Tripping
·
Check the current and voltage connections by applying small
signals to the connected current and voltage inputs. Trigger an
event report using the
TRIGGER
command. Plot the magnitude
and angle of measured currents and voltages.
·
Check the TR, TRCOMM, and TRSOTF settings to determine
which elements are enabled to trip.
·
Check the output logic equation settings to determine which outputs
are enabled to trip.
·
Check the settings of elements that are enabled to trip.
·
Check the settings of elements that supervise elements that are
enabled to trip.
Incorrect Distance
Element Characteristic
Shape
·
Check the voltage and current connections by applying small
signals to the connected current and voltage inputs. Trigger an
event report using the
TRIGGER
command. Plot the magnitude
and angle of measured currents and voltages.
·
Verify the distance element settings, including Zone 1 Extension
logic settings.
·
Verify the supervisory overcurrent element settings which apply to
the element under test: 50PP overcurrent elements supervise the
phase distance elements; 50GZ and 50L overcurrent elements
supervise the ground mho and quadrilateral distance elements.
·
Verify the directional element settings. 32QF supervises forward-
reaching phase and ground distance elements. 32QR supervises
reverse-reaching phase and ground distance elements.
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