Schweitzer Engineering Laboratories SEL-251 - Access Level 1 Commands; 2 Access; Breaker

Date Code 970103 Communications 3-7
SEL-251, -2, -3 Instruction Manual
If you enter incorrect passwords during three consecutive attempts, the relay pulses the ALARM
contact closed for one second. This feature can alert personnel to an unauthorized access attempt
if the ALARM contact is connected to a monitoring system.
Access Level 1 Commands
2ACCESS
2ACCESS allows you to enter Access Level 2. The password is required unless you install
jumper JMP103. The second password is set to TAIL at the factory; use the Level 2 command
PASSWORD to change passwords.
The following display indicates successful access:
=>2ACCESS <ENTER>2ACCESS <ENTER>
Password: TAIL <ENTER>TAIL <ENTER>
Example 21.6 kV distribution feeder Date: 04/01/93 Time: 14:12:01
Level 2
=>>
You may use any command from the =>> prompt. The relay pulses the ALARM output contact
closed for one second after any Level 2 access attempt (unless an alarm condition exists). If
access is denied, the ALARM output contact pulses again.
BREAKER
BREAKER displays running sums of circuit breaker trips for relay and external trips and
interrupted current in each circuit breaker pole for relay and external trips.
Relay trips are determined by coinciding change in circuit breaker auxiliary contact input status
(52A drops out or 52B asserts) and relay TRIP output contact assertion. Consideration should be
given to the TDUR (trip duration) timer setting so TRIP output contact assertion always
encompasses the status change of the circuit breaker auxiliary contact for a relay initiated trip.
See the note concerning circuit breaker status input options in the SET G command section.
External trips are determined by coinciding change in circuit breaker auxiliary contact input
status (52A drops out or 52B asserts) and the absence of relay TRIP output contact assertion.
For trips, the relay measures interrupted current in each pole one cycle after the rising edge of
TRIP contact assertion.
For external trips, the relay measures interrupted current in each pole when the status of the
circuit breaker auxiliary contact input changes (52A drops out or 52B asserts). Remember to
consider the time delay between the change of circuit breaker auxiliary contact status and the
opening of circuit breaker main contacts. If circuit breaker auxiliary contact operation lags too
far behind circuit breaker main contact operation, current may already be interrupted when the
circuit breaker auxiliary contact changes status. Thus, no interrupted current would be measured.