Schweitzer Engineering Laboratories SEL-701 - Self-Testing

Date Code 20010719 701 Motor Protection Relay
Maintenance & Troubleshooting
Self-Testing
10.3
Self-Testing
The relay runs a variety of self-tests. As shown below, when the relay detects
certain types of self-test failures, it closes the ALARM output b-contact. Monitoring
this contact is the single most important relay maintenance activity that you can
perform.
The relay takes the following actions for out-of-tolerance conditions in
Table 10.2.
Protection Disabled
The relay:
 Disables all protection functions and stop/start logic.
 Deenergizes all output contacts.
 Extinguishes the Relay Enabled front-panel LED.
ALARM Output
The ALARM output contact signals an alarm condition by going to its
deenergized state.
 The ALARM output b-contact closes for an alarm condition; the
ALARM output a-contact opens for an alarm condition or if the relay
is deenergized.
 The relay generates a STATUS report at the serial port for failures.
 The relay displays failure messages on the relay display.
Use the serial port STATUS command or front-panel Status of Relay function to
view the relay self-test status.
Table 10.2 Re lay S elf-Tests
Table 10.2 Relay Self-Tests
Self-Test Description Limits
Protection
Disabled
on Failure
ALARM
Output
on Failure
Front-Panel
Message
on Failure
DC Offset Measures the dc
offset at each of
the input
channels.
160 mV Yes Latched OFFSET
FAILURE
+5 V PS Measures the
+5 V power
supply.
+4.65 V
+5.65 V
Yes Latched +5V FAILURE
(Continued)