Inputs/Outputs; Contact Inputs - GE T60 Instruction Manual

CHAPTER 5: SETTINGS
∆t is the power cycle duration
n is the power cycle index
t is the trip time calculated at index n as per the IEC255-8 cold curve or hot curve equations
op(In)
t is the reset time calculated at index n as per the reset time equation
rst(In)
I is the measured overload RMS current at index n
n
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 5-44: Typical time constants
Protected equipment
Capacitor bank
Overhead line
Air-core reactor
Busbar
Underground cable
The figure shows the logic for the thermal overload protection element.

5.9 Inputs/outputs

5.9.1 Contact inputs

SETTINGS  INPUTS/OUTPUTS  CONTACT INPUTS
 CONTACT INPUTS

T60 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
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
Figure 5-214: Thermal overload protection logic
output operand when E < 0.05. In case of
THERM PROT 1 RESET
INPUTS/OUTPUTS
setting.
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