Arbiter Systems 928A, Руководство пользователя, Страница: 62 / 120

PQ – Power Quality, Sags and Swells
Method
The Model 928A measures sags, swells and power in-
terruptions by using the
PQ power quality triggering
function. PQ follows the CBEMA method of mea-
suring the signals at Channels A and B, comparing
them to point limits over assigned time intervals. The
rules used to measure the two input signals, including
Point Limits, are called a Profile. An example of the
CBEMA method used in the 928A is illustrated below.
Figure 4, drawn in a manner after the CBEMA
method, models some sag/swell voltage limits and time
intervals set in the 928A. Time intervals are normally
configured as an integer multiple of a half cycle at the
nominal frequency.
Figure 4: Point Limit Profile
48