Application coordination, Application coordination -7, Figure 4-6. typical dc connections – Basler Electric BE1-50/51B-230 User Manual
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BE1-50/51B-230/-234/-239 Installation
4-7
Figure 4-6. Typical DC Connections
Application Coordination
In a typical application coordination scheme, a BE1-50/51B-230, BE1-50/51B-234, or BE1-50/51B-239 is
used to provide primary protection for a radial distribution feeder. An electromechanical overcurrent relay
with extremely inverse timing provides protection for the transformer and bus. To improve coordination
with the electromechanical relay, the BE1-50/51B-230, BE1-50/51B-234, or BE1-50/51B-239 is
configured with the following settings:
•
Integrating reset enabled (SW3-4 ON)
•
Time characteristic curve E (extremely inverse) selected
•
ABB type curves selected (SW3-3 OFF)
•
Time dial set at 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 10 times pickup), calculate the feeder breaker trip time for each of the
three operations. Refer to Appendix A for the characteristic curve constants and definition of the terms
used in the following time characteristic curve equations.
From the time characteristic curve equation:
K
BD
C
M
AD
T
N
T
+
+
−
=
028
.
0
)
2
02758
.
0
(
1
10
2
7624
.
7
0938
.
2
+
×
+
−
×
=
=
0.209 seconds