GE D30 Instruction Manual page 337

5 SETTINGS
• E is the accumulated energy at index n.
n
• E is the accumulated energy at index n – 1.
n – 1
The thermal overload protection element removes the
emergency, the thermal memory and
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.
Table 5–23: TYPICAL TIME CONSTANTS
PROTECTED EQUIPMENT
Capacitor bank
Overhead line
Air-core reactor
Busbar
Underground cable
The logic for the thermal overload protection element is shown below.
Figure 5–113: THERMAL OVERLOAD PROTECTION SCHEME LOGIC
GE Multilin
THERMAL PROT 1 OP
output operand can be reset using
THERMAL PROT 1 OP
TIME CONSTANT MINIMUM RESET TIME
10 minutes 30 minutes
10 minutes 20 minutes
40 minutes 30 minutes
60 minutes 20 minutes
20 to 60 minutes 60 minutes
D30 Line Distance Protection System
5.7 CONTROL ELEMENTS
output operand when E < 0.05. In case of
THERM PROT 1 RESET
setting.
5
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