8.6
SEL-734 Meter Instruction Manual Date Code 20090730
Logic
Latch Bits
in SELOGIC control equations (see Latch Bits Set/Reset Equations (see
Figure 8.5) on page SET.3 of the SEL-734 Settings Sheets for latch bit
settings).
These latch control switches each have the following SEL
OGIC control
equation settings:
SETn (set latch bit LTn to logical 1)
RSTn (reset latch bit LTn to logical 0)
If setting SETn asserts to logical 1, latch bit LTn asserts to logical 1. If setting
RSTn asserts to logical 1, latch bit LTn deasserts to logical 0. If both settings
SETn and RSTn assert to logical 1, setting RSTn has priority and latch bit LTn
deasserts to logical 0.
Latch Bits: Application Ideas
Latch control switches can be used for such applications as:
➤ Battery charger health status alarm latching
➤ Predictive demand alarm enable/disable
Latch control switches can be applied to almost any control scheme. The
following is an example of using a latch control switch to add the battery
charger health status to the meter ALARM contact (output contact OUT103 by
default).
Example: Adding Battery Charger Health Status to ALARM Contact
Use a latch control switch to add battery charger health status alarm latching
to the SEL-734. In this example, a SCADA contact is connected to
optoisolated input IN102 as shown in Figure 8.6. Use a Remote Bit instead of
an input if your application warrants it.
If the ALARM output contact is enabled and the battery charger health status
contact is pulsed, the ALARM output contact is then disabled. If the battery
charger health status contact is pulsed again, the ALARM output contact is
enabled again. Each pulse of the battery charger health status contact changes
the state of the ALARM output contact. The control operates in a cyclic manner.
The battery charger health status contact is not maintained, just pulsed to
enable/disable the ALARM output contact.
Figure 8.6 Battery Charger Health Status Contact Pulses Input IN102 to
Enable/Disable ALARM Output Contact
(+)
Battery Charger
Health Status
Contact
(—)
SEL Input IN102
Enable/Disable ALARM
Output Contact
Courtesy of NationalSwitchgear.com
To Next Page
Loading...