GE LPS-O, Инструкция по эксплуатации

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GE Power Management LPS-O Line Protection System 13-
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13 XPRESSION BUILDER 13.2 DESIGN CONSIDERATIONS
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The second type of timer is basically a pickup delay timer with a reset input/output feature. As shown in Figure
13–7: PICKUP DELAY TIMER, there are two inputs, two outputs, and a user selected pickup delay (in millisec-
onds). In its “initial” state with no inputs applied, both R and S are low (binary 0), the timer outputs RO and SO
are both low (binary 0). The timer starts counting when the S input is high (binary 1). When the count becomes
equal to the set time delay (1000 ms for our example), the SO output is set high (binary 1) and the RO output
is set low (binary 0). If the R input becomes high (binary 1) while the timer IS NOT counting, then both outputs
RO and SO are set low (binary 0) which returns the timer to its “initial state”. See Table 13–1: PICKUP DELAY
TIMER TRUTH TABLE for a summary of the pickup delay timer function.
Figure 13–7: PICKUP DELAY TIMER
d) COUNTERS
The counter has two input line, one output line, and a user selected count threshold (in milliseconds) as shown
in Figure 13–8: COUNTER. A transition from low (binary 0) to high (binary 1) on the S input line increments the
counter by a value of one. The O output line is high (binary 1) when the accumulated count is equal to or
greater than the count threshold. If the O output line is low (binary 0), then the accumulated count is less than
the set value. A transition from low (binary 0) to high (binary 1) on the R input line resets the counter to zero.
Figure 13–8: COUNTER
Table 13–1: PICKUP DELAY TIMER TRUTH TABLE
S R PREVIOUS TIMER STATE CURRENT TIMER STATE RO SO
L L NOT TIMING NOT TIMING RO
n-1
L
↑
L NOT TIMING TIMING DOWN L L
X L TIMING DOWN TIMER EXPIRED L H
X H TIMING DOWN TIMER RESET H L
X
↑
NOT TIMING NOT TIMING L L
1000
R
S S O
R O
0 0 0 0
S
R
O
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