4.119
Date Code 20100129
Instruction Manual
SEL-751A Relay
Protection and Logic Functions
Front-Panel Settings (SET F Command)
Local Bits
Local bits are variables (LB
nn
, where
nn
means 01 through 32) that are
controlled from front-panel pushbuttons. Use local bits to replace traditional
panel switches. Each local bit requires three of the following four settings,
using a maximum of 14 valid characters for the NLB
nn
setting, and a
maximum seven valid characters (0–9, A–Z, -, /, ., space) for the remainder:
➤
NLB
nn
: Name the switch (normally the function that the switch
performs, such as SUPERV SW) that will appear on the LCD
display.
➤
CLB
nn
: Clear local bit. Enter the text that describes the
intended operation of the switch (this text appears on the
display) when LB
nn
deasserts (OPEN, for example).
➤
SLB
nn
: Set local bit. Enter the text that describes the intended
operation of the switch (this text appears on the display) when
LB
nn
asserts (CLOSE, for example).
➤
PLB
nn
: Pulse local bit. When selecting the pulse operation,
LB
nn
asserts for only one processing interval before
deasserting again. Enter the text that describes the intended
operation when LB
nn
asserts (START, for example).
➤
Omit either SLB
nn
or PLB
nn
(never CLB
nn
) by setting the
omitted setting to NA.
For the transformer in our example, configure two local bits: one to replace a
supervisory switch, and the other to start a fan motor. Local bit 1 replaces a
supervisory switch (SUPERV SW) and we use the clear/set combination.
Local bit 2 starts a fan motor (START) that only needs a short pulse to seal
itself in, and we use the clear/pulse combination.
shows the
settings to program the two local bits.
Summary of Contents for 751A
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