Schweitzer Engineering Laboratories SEL-387E - Latch Bit Behavior for Power Loss, Settings Change, Active Group Change; Note: Make Latch Bit Settings with Care; Output Contacts; Factory Settings Example

Date Code 20080110 Control Logic 4-11
SEL-387E Instruction Manual
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 change. When the active group changes are enabled
in the relay, the latch bits will respond to the states of the SnSLTm (Set) and SnRLTm (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-387E Relay behave exactly like traditional latching
relays.
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.
O UTPUT C ONTACTS
SEL OGIC control equation settings control Relay Word bits having the same names. These Relay
Word bits in turn control the output contacts (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