Latch Control Switch Settings; Figure B.4 Traditional Latching Relay; Figure B.5 Latch Control Switches Drive Latch Bits Lt1 Through Lt4 - Schweitzer Engineering Laboratories SEL-701 Instruction Manual

Latch Control Switch Settings

The latch control switch feature of the SEL-701 Relay replaces latching relays.
The state of a traditional latching relay output contact is changed by pulsing the
latching relay inputs. (See
relay output contact. Pulse the reset input to open (reset) the latching relay output
contact.
(+)
(–)

Figure B.4 Traditional Latching Relay.

Four latch control switches in the SEL-701 Relay provide latching relay type
functions.
SEL
OGIC
Settings
SETn
(set)
RSTn
(reset)

Figure B.5 Latch Control Switches Drive Latch Bits LT1 through LT4.

The output of the latch control switch in
(n = 1–4), called a latch bit. The latch control switch logic in
each latch bit LT1 through LT4. Use these latch bits in SEL
These latch control switches each have the following SEL
settings:
SETn sets latch bit LTn to logical 1 when SETn SEL


equation result is logical 1.
RSTn reset latch bit LTn to logical 0 when RSTn SEL


equation result is logical 1.
If both SETn and RSTn assert to logical 1, RSTn has priority and latch bit LTn
deasserts to logical 0.
Date Code 20010719
Figure B.4). Pulse the set input to close (set) the latching
Set Input
Traditional
Latching Relay
(n = 1 through 4)
Figure B.5
OGIC ®
SEL Control Equations & Relay Logic
Latch Control Switch Settings
Reset Input
Output
Contact
Relay
Word
Bit
LTn
is a Relay Word bit LTn
Figure B.5
control equations.
OGIC
OGIC
701 Motor Protection Relay
B.17
repeats for
control equation
control
OGIC
control
OGIC