5-206
F35 Multiple Feeder Protection System
GE Multilin
5.7 CONTROL ELEMENTS
5 SETTINGS
5
To ensure element accuracy for high overcurrent conditions, the maximum value of I/(k x I
B
) is limited to 8, even when real-
istically it is exceeding this value.
The reset time of the thermal overload protection element is also time delayed using following formula:
(EQ 5.24)
In the above equation,
•
τ
rst
= thermal protection trip time constant
•
T
min
is a minimum reset time setting
Figure 5–92: IEC 255-8 SAMPLE OPERATE AND RESET CURVES
The thermal overload protection element estimates accumulated thermal energy
E
using the following equations calculated
each power cycle. When current is greater than the pickup level,
I
n
>
k
×
I
B
, element starts increasing the thermal energy:
(EQ 5.25)
t
rst
τ
rst
kI
B
(
)
2
I
2
kI
B
(
)
2
–
-----------------------------
ln
×
T
min
+
=
0.1
1
10
100
I / Ipkp
t (min)
0.01
0.1
1
10
100
τ
= 30
rst
τ
= 30
op
T
= 10
min
827724A1.CDR
E
n
E
n
1
–
t
Δ
t
op In
( )
---------------
+
=
Summary of Contents for UR F35 Series
Page 10: ...x F35 Multiple Feeder Protection System GE Multilin TABLE OF CONTENTS ...
Page 366: ...5 238 F35 Multiple Feeder Protection System GE Multilin 5 10 TESTING 5 SETTINGS 5 ...
Page 426: ...10 12 F35 Multiple Feeder Protection System GE Multilin 10 6 DISPOSAL 10 MAINTENANCE 10 ...
Page 454: ...A 28 F35 Multiple Feeder Protection System GE Multilin A 1 PARAMETER LISTS APPENDIX A A ...
Page 620: ...F 12 F35 Multiple Feeder Protection System GE Multilin F 2 DNP POINT LISTS APPENDIX F F ...
Page 630: ...H 8 F35 Multiple Feeder Protection System GE Multilin H 3 WARRANTY APPENDIX H H ...
Page 640: ...x F35 Multiple Feeder Protection System GE Multilin INDEX ...