Basler BE1-50/51B-218 - Page 37

9252000995 Rev G BE1-50/51B-218/-228 Installation 4-5
curve E (extremely inverse) selected (SW3-3 set to OFF) and the TIME DIAL set to 2.0. The feeder
reclosing relay is set for two reclose attempts at 3 and 15 seconds after the initial trip. If a permanent fault
occurs (magnitude ten times pickup), calculate the feeder breaker trip time for each of the three
operations. Refer to Section 1 for characteristic curve constants.
From the time characteristic curve equation.
KBD
CM
AD
T
N
Trip
++
−
=
()
0280202758.0
110
276247
09382
.
.
.
+×+
−
×
=
() 028005516.0
110806124
524815
.
.
.
++
−
=
seconds 0.29
=
From the reset characteristic curve equation.
1M
RD
T
2
Reset
−
=
seconds 15.5
10
27.75
2
−=
−
×
=
M = 0 if current goes to zero.
Negative result indicates reset time.
Results: Full trip = 0.209 seconds and full reset = 15.5 seconds if current goes to zero.
In Figure 4-5,
T
A
= 0.209 seconds (relay was at reset).
T
B
= value < T
A
because rewind has not gone to zero.
T
C
= value < T
A
because rewind has not gone to zero.
Figure 4-5. Coordination Timing Diagram