Date Code 20001006 Testing and Troubleshooting 13-3
SEL-351 Instruction Manual
TESTING METHODS AND TOOLS
Test Features Provided by the Relay
The following features assist you during relay testing.
METER
Command
The METER command shows the ac currents and voltages (magnitude and
phase angle) presented to the relay in primary values. In addition, the
command shows power system frequency (FREQ) and the voltage input to
the relay power supply terminals (VDC). Compare these quantities against
other devices of known accuracy. The METER command is available at the
serial ports and front-panel display. See Section 10: Serial Port
Communications and Commands and Section 11: Front-Panel Interface.
EVENT
Command
The relay generates a 15- or 30-cycle event report in response to faults or
disturbances. Each report contains current and voltage information, relay
element states, and input/output contact information. If you question the
relay response or your test method, use the event report for more
information. The EVENT command is available at the serial ports. See
Section 12: Standard Event Reports, Sag/Swell/Interruption Report, and
SER.
SER
Command
The relay provides a Sequential Events Recorder (SER) event report that
time-tags changes in relay element and input/output contact states. The SER
provides a convenient means to verify the pickup/dropout of any element in
the relay. The SER command is available at the serial ports. See Section
12: Standard Event Reports, Sag/Swell/Interruption Report, and SER.
TARGET
Command
Use the TARGET command to view the state of relay control inputs, relay
outputs, and relay elements individually during a test. The TARGET
command is available at the serial ports and the front panel. See Section 10:
Serial Port Communications and Commands and Section 11: Front-Panel
Interface.
PULSE
Command
Use the PULSE command to test the contact output circuits. The PULSE
command is available at the serial ports and the front panel. See Section 10:
Serial Port Communications and Commands.
Low-Level Test Interface
The SEL-351 Relay has a low-level test interface between the calibrated input module and the
separately-calibrated processing module. You may test the relay in either of two ways:
conventionally, by applying ac current signals to the relay inputs or by applying low magnitude
ac voltage signals to the low-level test interface. Access the test interface by removing the relay
front panel.
Figure 13.1 shows the low-level interface connections. This drawing also appears on the inside
of the relay front panel. Remove the ribbon cable between the two modules to access the outputs
of the input module and the inputs to the processing module (relay main board).
Courtesy of NationalSwitchgear.com
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