Date Code 20011026 Maintenance and Testing 7-3
SEL-321/321-1 Instruction Manual
The Hertz specification indicates the relay is designed to measure ac voltage and
current signals at the nominal system frequency. The relay is designed to make
accurate voltage and current measurements during frequency excursions, as defined
in Section 2: Specifications.
Step 3.
Purpose: Connect power supply voltage to the relay.
Method: If the relay is equipped with a rear panel power switch, move the switch to
the `OFF' position. Connect a frame ground to terminal marked GND on the rear
panel and connect a voltage source to the terminals marked + and -. Polarity is
unimportant. Relays equipped with 125 or 250 V power supplies may be powered
from a 115 Vac wall receptacle for testing. In the final installation, we recommend
that the relay receive control power from the station dc battery. This helps prevent
loss of relay event reports stored in volatile memory if station ac service is lost.
Step 4.
Purpose: Apply power supply voltage to the relay and access the relay via the LCD
front panel.
Method: Turn on the voltage source connected to the relay power supply inputs. If
the relay is equipped with a power switch, move the relay power switch to the `ON'
position. If you are using a battery simulator as the relay power supply voltage
source, be sure the simulator voltage level is stabilized before turning the relay on.
The relay front panel Enable target (EN) should illuminate. EN should appear in the
relay LCD screen.
The relay output labeled ALARM is typically configured as a normally closed (form
“b”) contact and closes to indicate loss of dc power to the relay, failure of a relay
self-test, and several other functions. With power applied to the relay and the relay
turned on, the ALARM contacts open.
If the Enable LED does not illuminate or EN does not appear on the relay LCD
screen, turn off the power and refer to Relay Troubleshooting later in this section.
Step 5.
Purpose: Perform a front panel LED test and check LCD screen contrast.
Method: Press the TARGET RESET button to perform an LED lamp test. During
the lamp test, the relay illuminates all 16 front panel LEDs for about one second.
The relay also turns on the LCD back lighting. If the LCD contrast is poor, refer to
the Relay Troubleshooting Table in this section for steps to adjust it.
Step 6.
Purpose: Verify the relay self-test status.
Method: Press the front panel STATUS button. The message STATUS: OK
should appear on the relay LCD screen. Use the Up and Down arrow buttons to
view the results of specific relay self-tests. Press the front panel CANCEL or EXIT
button to exit the STATUS display.
To Next Page
Loading...
