Basler Electric BE1-BPR - Manual (Page 26)

2-2 BE1-BPR Application 9272000990 Rev J
level is less than 40 milliamperes above the pickup setting. This prevents noise induced trips from
occurring. The Type 1 is used in BF logic schemes and is programmed by setting the fault detector logic
(LF) type to PI (phase overcurrent) or NI (neutral overcurrent) and the digital filter selection to 1.
For the fault detector to pickup, the RMS value of the last cycle of current must be above the pickup
setting. Due to the analog input circuitry design, the RMS value is clamped (limited) at approximately 13
amperes. As the multiple of pickup level increases, the pickup time decreases. Because of the limiting
above 13 amperes, the pickup time does not appreciably decrease at high multiples of pickup. Also, the
pickup may be delayed up to one-quarter cycle because the RMS current is calculated every quarter
cycle. However, in no case will the pickup be slower than one and one-quarter cycles.
Figure 2-1 shows maximum pickup timing versus current input levels.
Figure 2-1. Maximum Instantaneous Pickup Timing
For the Type 1 fault detector to dropout, one of two conditions must occur. One, three sequential analog-
to-digital (A/D) samples must be less than one-fourth of the RMS current level for the last quarter-cycle
calculation. Two, the RMS current signal level must decrease to less than 75% of pickup. Samples are
made twelve times per line cycle and RMS current is calculated four times per line cycle. Three samples
are used to compensate for zero crossings and noise. A short dropout delay is advantageous for BF logic
in order to allow for the minimum timing margin in critical applications.
Figure 2-2 shows maximum dropout timing versus current input levels.
4
6
8
10
12
14
16
18
20
22
1.05 1.25 2 5 20 40
MULTIPLES OF PICKUP
M
A
X.
P
IC
K
U
P
TI
M
E
(m
s)
PU=5.00A
PU=0.25A
PU=9.99A
D2838-21