GE Multilin
T60 Transformer Protection System
5-261
5 SETTINGS
5.7 CONTROL ELEMENTS
5
(EQ 5.53)
In the above equations,
•
∆
t
is the power cycle duration.
•
n
is the power cycle index.
•
t
op
(
In
)
is the trip time calculated at index
n
as per the IEC255-8 cold curve or hot curve equations.
•
t
rst
(
In
)
is the reset time calculated at index
n
as per the reset time equation.
•
I
n
is the measured overload RMS current at index
n
.
•
E
n
is the accumulated energy at index
n
.
•
E
n
– 1
is the accumulated energy at index
n
– 1.
The thermal overload protection element removes the
THERMAL PROT 1 OP
output operand when
E
< 0.05. In case of
emergency, the thermal memory and
THERMAL PROT 1 OP
output operand can be reset using
THERM PROT 1 RESET
setting.
All calculations are performed per phase. If the accumulated energy reaches value 1 in any phase, the thermal overload
protection element operates and only resets when energy is less than 0.05 in all three phases.
The logic for the thermal overload protection element is shown below.
Figure 5–147: THERMAL OVERLOAD PROTECTION SCHEME LOGIC
Table 5–25: TYPICAL TIME CONSTANTS
PROTECTED EQUIPMENT
TIME CONSTANT
MINIMUM RESET TIME
Capacitor bank
10 minutes
30 minutes
Overhead line
10 minutes
20 minutes
Air-core reactor
40 minutes
30 minutes
Busbar
60 minutes
20 minutes
Underground cable
20 to 60 minutes
60 minutes
E
n
E
n
1
–
t
Δ
t
rst In
( )
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Summary of Contents for UR T60
Page 10: ...x T60 Transformer Protection System GE Multilin TABLE OF CONTENTS ...
Page 14: ...xiv T60 Transformer Protection System GE Multilin 0 1 BATTERY DISPOSAL 0 BATTERY DISPOSAL 0 ...
Page 34: ...1 20 T60 Transformer Protection System GE Multilin 1 5 USING THE RELAY 1 GETTING STARTED 1 ...
Page 436: ...5 298 T60 Transformer Protection System GE Multilin 5 10 TESTING 5 SETTINGS 5 ...
Page 678: ...C 30 T60 Transformer Protection System GE Multilin C 7 LOGICAL NODES APPENDIX C C ...
Page 688: ...D 10 T60 Transformer Protection System GE Multilin D 1 IEC 60870 5 104 PROTOCOL APPENDIX D D ...
Page 700: ...E 12 T60 Transformer Protection System GE Multilin E 2 DNP POINT LISTS APPENDIX E E ...
