Sel 411L - Page 662

P.9.16
SEL-411L Relay Protection Manual Date Code 20151029
Monitoring and Metering
Circuit Breaker Monitor
When testing the inactivity timer, you must measure actual relay clock
transitions across time 00:00:00.000 (to increment the day counter). If you set
the relay to a specific date, enable the circuit breaker monitor
(EB1MON := Y), then advance the date setting to a new date, the inactivity
timer shows only 1 day of elapsed time.
Motor Running Time
The relay circuit breaker monitor measures circuit breaker motor running
time. Depending on your circuit breaker, you can use the motor running time
to monitor the charge time of the circuit breaker springs or the running time of
the compressed air motor. An alarm asserts if the elapsed motor running time
exceeds the predefined threshold setting B1MRTAT.
Setting B1MRTIN is a SEL
OGIC control equation to activate the
motor-running timer. The rising edge of B1MRTIN indicates the motor
starting time; a falling edge indicates the motor stop time. The motor running
time logic asserts the alarm Relay Word bit, B1MRTAL, for 5 seconds when
the motor running time exceeds the predefined threshold. Setting B1MRTIN
to logical 0 disables the motor running time feature of the circuit breaker
monitor.
EXAMPLE 9.10 Motor Running Time Settings
Use Circuit Breaker 1 for this example.
Connect the motor control contact to IN207. This example uses
control input IN207; you can use any control inputs that are
appropriate for your installation.
To determine the motor run time value, take the circuit breaker out of
service using your company standard circuit breaker maintenance
policy. Issue a trip and close command while you measure the time
that the circuit breaker motor requires for recharging the spring or
reestablishing the return air pressure to normal. Add 20 percent to
this time measurement to avoid false alarms. Use the resulting time
value for the motor running time alarm setting B1MRTAL.
The control voltage for this example is 125 Vdc. Control Input IN207 is
located on the relay I/O Interface board #1.
The recharge time measurement for this circuit breaker was 20
seconds; add 20 percent (4 seconds) to give an alarm time of 24
seconds. To set the motor running time alarm threshold at 24
seconds, enter the following settings:
EB1MON := Y Breaker 1 Monitoring (Y, N)
B1MRTIN := IN207 Motor Run Time Control Input—BK1
(SEL
OGIC Equation)
B1MRTAT := 24 Motor Run Time Alarm Threshold—BK1
(1–9999 seconds)
Assertion of the Relay Word bit B1MRTAL indicates the following
condition: motor running time exceeds 24 seconds because IN207
was asserted for more than 24 seconds.
BREAKER Command
Use the BRE command to access vital information about the condition of
substation circuit breakers and preset or reset circuit breaker monitor data. The
relay monitors two separate circuit breakers; you must specify Circuit
Breaker 1 and Circuit Breaker 2 for most BRE commands. Table 9.6 shows
the BRE commands. For more information on the BRE command, see
BREAKER on page P.15.4.