6.14 Device 49T - Machine Thermal Model - Fixed Parameter Thermal Overload; Table 6-12 Advanced Motor Protection Menu - Machine Thermal Model - Fixed Parameter Thermal - Siemens SINAMICS PERFECT HARMONY GH180 Function Manual

Advanced Motor Protection and RTD Protection Functions

6.14 Device 49T - Machine Thermal Model - Fixed Parameter Thermal Overload

6.14 Device 49T - Machine Thermal Model - Fixed Parameter Thermal
Overload
Overview
The fixed parameter thermal overload function uses a first order differential equation to track
the amount of thermal capacity used in the machine as described in IEC 60255-149. Thermal
capacity is used up as the machine temperatures approach maximum rated or allowable
conditions. An equivalent heating current is calculated that takes into account the RMS phase
currents of the machine as well as the amount of negative sequence current. The heat input to
the machine is determined based on the square of the equivalent heating current divided by an
adjustable rated current. The thermal capacity is adjusted based on thermal time constants for
heating, cooling, or stopped conditions in the machine in accordance with a first order
differential equation that accounts for heat inputs and heat outputs in the machine. The fixed
parameter function uses single values of rated current, heating time constant, and cooling time
constant. An adjustable threshold can be set to limit the maximum amount of thermal capacity
used. The function reports a trip or alarm condition or can block starting of the motor when the
thermal capacity used exceeds the programmed value. The thermal model of the machine can
be biased by RTD measurements of ambient temperature and/or stator temperature. Ambient
RTD readings are used to compensate for the effects of an ambient temperature other than
rated, stator RTD readings are used to set minimum thermal capacity used values based on the
stator temperature.
Device 49T provides parameter status as shown in table
Machine Thermal Model - Fixed Parameter Thermal Overload.
Table 6-12 Advanced Motor Protection Menu - Machine Thermal Model - Fixed Parameter Thermal Overload (ID 7335)
Keypad Parameter Text
Tool Parameter Text
Alarm Pickup Level
Trip Pickup Level
Heating Time Constant
Cooling Time Constant
Stopped Time Constant
Curve k-factor
Negative Seq q-Factor
Tmax
Tlimit
Tmaxoper
HCSR
Picklist
Use Ambient RTDs
Use Stator RTDs
58
ID Units
7336 %
7337 %
7338 min
7339 min
7340 min
7341
7342
7345 °
7346 °
7347 °
7348
ID Units
7343 No Ambient
7344
Advanced Motor Protection Menu -
Default Minimum - Maximum Value
Value
80
100
15
15
30
1.15
4
180
40
130
1
Default
Value
● No Ambient
● Use Ambient
No Stator
● No Stator
● Use Stator
Advanced Motor Protection for Variable Speed Operation
0 - 150
0 - 150
1 - 1000
1 - 1000
1 - 1000
1 - 1.5
0 - 15
50 - 572
25 - 212
50 -572
0.1 - 1
Values
Manual, AA, A5E46373908A