Arbiter Systems Portable Power Sentinel 933A, Руководство по эксплуатации

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is a 16-bit unsigned integer, having a range of 0 to 65535 cycles. Since
comparisons are performed 20 times per second, this corresponds to a
range of dwell time of 0 to 3276.75 seconds. A value of 0 allows the trigger
to be recognized at any time the corresponding condition is true; a value of
1 (0.05 seconds) requires the trigger condition to persist for two consecutive
comparisons, and so on.
Considering all of the different input signal possibilities, along with the
different limit modes and inter-channel dependencies, there are an almost
limitless number of possible combinations of settings for each trigger
channel.
9.26 Detecting Oscillatory Transients and
Other Anomalies
Special logic is included in the 933A to implement the algorithms described
by Schulz and Laios [1], which are designed to detect power system
anomalies such as oscillatory transients. There are six channels dedicated
to performing this function in the 933A (Table 4). Each of these may
have any of the 124 signals described above as its input. Each channel
has three outputs: a low-pass-filtered (‘bound’) output, a rate-of-change
output, and an oscillation-detector output. Each channel also has three
control parameters (in addition to the input signal selection): the rate-
of-change filter time constant (T1 in [1]); the oscillation-detector time
constant (T2 in [1]); and the oscillation-detector reset threshold, also
described in [1]. These parameters control only the operation of these
signal-processing blocks, and do not in themselves generate any triggers.
To generate triggers, select one of the three outputs of one of the channels
in this block. This serves as an input to one of the 32 trigger channels. As
recommended by Schulz and Laios, the input filtering for this block is the
BPA #1 low-pass, described in [2], which is a 12-point Hanning-weighted
FIR low-pass filter having a group delay of 0.3 seconds at a 20/second
sampling rate.
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