Thermal Model Unit (49); 49 Unit Setpoints - GE Multilin F650 Instruction Manual

5.4 PROTECTION ELEMENTS

5.4.3.4 THERMAL MODEL UNIT (49)

Unit 49 is a protection element that measures the thermal heating generated as a result of the flowing current, and prevents
this heating from causing damage to the protected equipment. In order to calculate the thermal image value, the following
equation is used:
Where,
τ is the heating/cooling time constant.
I is the ratio current/pickup
When a body is cooled, it does not always follow a time constant similar to the heating time constant; this is why the
function has independent setpoints for heating and cooling constants.
Table 5–43: 49 UNIT SETPOINTS
SETPOINT > PROTECTION ELEMENTS > PHASE CURRENT > THERMAL MODEL >
THERMAL MODEL 1> THERMAL MODEL 2 > THERMAL MODEL 3
SETPOINT DESCRIPTION
5
Function permission
Heating constant
Cooling constant
Pickup level
Alarm level
Snapshot event generation
The cooling constant is given in times the heating constant.
The snapshot event setpoint enables or disables the snapshot event generation for the thermal model units.
5-48
τ
=
t * Ln
NAME DEFAULT
VALUE
Function DISABLED
Heat Time Constant 6.0
Cool Time Constant 2.00
Pickup Level 1.00
Alarm Level 80.0
Snapshot Events ENABLED
F650 Digital Bay Controller
2 '
I
−
2 '
I 1
STEP
N/A
0.1 min
0.01 times Heat Time Ct.)
0.01 A
0.1 %
N/A
5 SETPOINTS
RANGE
[DISABLED – ENABLED]
[3.0 : 600.0]
[1.00 : 6.00]
[0.05 : 160.00]
[1.0 : 110.0]
[DISABLED – ENABLED]
GE Multilin