Schweitzer Engineering SEL-387-0, Instruction Manual

Page: 137 / 556

4.11
Date Code 20170601 Instruction Manual SEL-387-0, -5, -6 Relay
Control Logic
Output Contacts
If setting S n SLT m (Set) asserts to logical 1, latch bit S n LT m asserts to
logical 1 and seals itself via the OR and AND gates. If setting S n RLT m
(Reset) asserts to logical 1, the seal-in is broken and latch bit S n LT m deasserts
to logical 0. If both settings S n SLT m and S n RLT m assert to logical 1, setting
S n RLT m (Reset) takes precedence, and latch bit S n LT m deasserts to logical 0.
Latch Bit Behavior for Power Loss, Settings Change, Active Group Change
If power to the relay is lost and then restored, the states of the latch bits remain
unchanged. This is done by retaining the latest states of the latch bits in
EEPROM, where they can be recovered on power up of the relay.
If settings are changed in one of the nonactive setting groups, the states of the
latch bits remain the same.
If settings are changed in the active setting group, or if a new setting group is
selected to be the active group, the states of the latch bits may or may not
change. When the active group changes are enabled in the relay, the latch bits
will respond to the states of the S
n SLT m (Set) and S n RLT m (Reset) equations,
in the manner discussed above for Figure 4.5 . The new latch bit states thus
depend on the original state of the latch bit and on the effects of the user
changes upon the set and reset equations.
The net effect is that the latch bits in the SEL-387 behave exactly like
traditional latching relays.
Output Contacts
SEL
OGIC
control equation settings OUT101 through OUT107 and OUT201
through OUT212 control Relay Word bits having the same names. These
Relay Word bits in turn control the output contacts
OUT101
through
OUT107
and
OUT201 through OUT212 (interface board). Alarm logic/circuitry controls the
ALARM output contact.
Factory Settings
Example
In the factory SEL
OGIC
control equation settings, all seven standard main
board output contacts are used:
OUT101 =
TRIP1
Used to trip Breaker 1
OUT102 =
TRIP2
Used to trip Breaker 2
OUT103 =
TRIP3
Used to trip Breaker 3
OUT104 = TRIP4 Used to energize 86 device for tripping Breakers 1
through 3
OUT105 = CLS1 Used to close Breaker 1
OUT106 =
CLS2
Used to close Breaker 2
OUT107 =
CLS3
Used to close Breaker 3
NOTE
: Make Latch Bit Settings With
Care.
The latch bit states are stored in
nonvolatile memory so they can be
retained during power loss, settings
change, or active setting group
change. The nonvolatile memory is
rated for a finite number of "writes"
for all cumulative latch bit state
changes. Exceeding the limit can
result in an EEPROM self-test failure.
An average of 70 latch bit changes per
day can be made for a 25-year relay
service life.