GE L60 Instruction Manual page 408

5.6 CONTROL ELEMENTS
• 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 5–32: 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.
5
5-276
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
Figure 5–141: THERMAL OVERLOAD PROTECTION SCHEME LOGIC
L60 Line Phase Comparison System
output operand when E < 0.05. In case of
THERMAL PROT 1 OP
output operand can be reset using
5 SETTINGS
setting.
THERM PROT 1 RESET
GE Multilin