Sel 551 - Table 3.4 Correspondence between Local Control Switch Types and Required Label Settings

3.6
SEL-551 Relay Instruction Manual Date Code 20110408
Relay Elements and Logic
Local Control Switches
If a local control switch is not being used, “null out” all its corresponding
label settings to make it inoperable (see Section 4: Setting the Relay). The
local bit that is “driven” by this inoperable local control switch is fixed at
logical 0.
Factory Settings
Example
Local bits LB1, LB3, and LB4 are used in a number of the factory settings in
this section. The factory settings examples control reclose enable/disable,
manual tripping, and manual closing. Their corresponding local control switch
position label settings are:
The operation of these local control switches through the front panel is
demonstrated in Section 6: Front-Panel Interface.
Additional Settings
Examples
Other application ideas for local bits are:
➤ ground relay enable/disable
➤ remote control supervision
➤ sequence coordination enable/disable
Local bits can be applied to almost any control scheme.
Table 3.4 Correspondence Between Local Control Switch Types and
Required Label Settings
Local
Switch Type
Label
NLBn
Label
CLBn
Label
SLBn
Label
PLBn
ON/OFF X X X
OFF/MOMENTARY X X X
ON/OFF/MOMENTARY X X X X
Local Bit Label Settings Function
LB1 NLB1 = RECLOSER enables/disables reclosing relay;
see Reclosing Relay on page 3.22
(setting 79DTL)
CLB1 = DISABLE OFF position
SLB1 = ENABLE ON position
PLB1 = MOMENTARY position—not used
LB3 NLB3 = MANUAL TRIP trips breaker and drive reclosing relay
to lockout; see Trip Logic on page 3.17 and
Reclosing Relay (setting 79DTL)
CLB3 = RETURN OFF position
(“return from MOMENTARY” position)
SLB3 = ON position—not used
PLB3 = TRIP MOMENTARY position
LB4 NLB4 = MANUAL CLOSE closes breaker, separate from
reclosing relay algorithm; see Close Logic on
page 3.20
CLB4 = RETURN OFF position (“return from
MOMENTARY” position)
SLB4 = ON position—not used
PLB4 = CLOSE MOMENTARY position