8.9
Date Code 20090730 Instruction Manual SEL-734 Meter
Logic
SEL
OGIC Control Equation Variables/Timers
the limit can result in a NONVOL self-test failure. An average of 70
cumulative latch bit state changes per day can occur for a 25-year meter
service life.
This requires that SEL
OGIC control equation settings SETn and RSTn for
any given latch bit LTn (n = 01 through 16) be set with care. Settings SETn
and RSTn cannot result in continuous cyclical operation of latch bit LTn. Use
timers to qualify conditions set in settings SETn and RSTn. If any optoisolated
inputs are used in settings SETn and RSTn, the inputs have their own
debounce timer that can help in providing the necessary time qualification.
In the preceding example application of adding a battery charger health status
to the ALARM contact (Figure 8.6), the battery charger health status contact
cannot be asserted/deasserted continuously, a situation that would cause latch
bit LT01 to change state continuously. Note that the rising edge operators in
the SET01 and RST01 settings keep latch bit LT01 from cyclical operation for
any single assertion of the battery charger health status contact.
Local Control Bit
The SEL-734 provides local control using the front-panel RESET pushbutton
and the Meter Word bit, RESET (see Meter Word Bits (Used in SEL
OGIC
Control Equations) on page 9.3). Any time the RESET pushbutton is pressed,
the RESET Meter Word changes state from logical 0 to logical 1 (asserts), and
changes back to logical 0 (deasserts) when the button is released. Use the
RESET bit as you would any other Meter Word bit in SEL
OGIC control
equations to perform a specific function when the RESET button is pressed. For
example:
OUT101 = RESET
When the RESET front-panel pushbutton is pressed, the Meter Word bit RESET
asserts, causing OUT101 to close. Releasing the pushbutton deasserts the
RESET bit, causing the output to open.
SELOGIC Control Equation Variables/Timers
The SEL-734 has sixteen (16) SELOGIC control equation variables/timers.
Each SEL
OGIC control equation variable/timer has a SELOGIC control
equation setting input and variable/timer outputs as shown in Figure 8.10.
Timers SV01T through SV16T in Figure 8.10 have a setting range of a little
over four minutes (see SEL
OGIC Variables Timer Settings on page SET.4 of the
SEL-734 Settings Sheets):
0.000–250.000 seconds in 25-ms increments
These timer setting ranges apply to both pickup and dropout times (SVnPU
and SVnDO, n = 01 through 16).
Figure 8.10 SELOGIC Control Equation Variables/Timers SV01/SV01T
Through SV16/SV16T
SVn
SVn
SVnT
SEL
OGIC Variable/
Timer Input Settings
Meter
Word Bits
SVnPU
SVnDO
Courtesy of NationalSwitchgear.com
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