GE ALPS Instruction Manual page 279

13 XPRESSION BUILDER
The second type of timer is basically a pickup delay timer with a reset input/output feature. As shown in Figure 13–4:
PICKUP DELAY TIMER, there are two inputs, two outputs, and a user selected pickup delay (in milliseconds). 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.
Table 13–1: PICKUP DELAY TIMER TRUTH TABLE
S R
L L
↑
L
X L
X H
↑
X
d) COUNTERS
The counter has two input line, one output line, and a user selected count threshold (in milliseconds) as shown in Figure
13–5: 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.
GE Power Management
1000
S
R
Figure 13–4: PICKUP DELAY TIMER
PREVIOUS TIMER STATE
NOT TIMING
NOT TIMING
TIMING DOWN
TIMING DOWN
NOT TIMING
S
0 0
R
Figure 13–5: COUNTER
ALPS Advanced Line Protection System
S O
R O
CURRENT TIMER STATE
NOT TIMING
TIMING DOWN
TIMER EXPIRED
TIMER RESET
NOT TIMING
5
0 0
O
13.1 INTRODUCTION
RO SO
RO L
n-1
L L
L H
H L
L L
13-3
13