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Safety
Product
Mechanical
information
information
installation
2.4.1
Typical short term overload limits
The maximum overload limit changes depending on the selected motor. Variations in motor rated current, motor power factor and motor leakage
inductance all result in changes in the maximum possible overload due to the thermal models estimation of the motor temperature as a percentage of
its maximum allowed temperature. Typical values for overload are shown in the table below:
Table 2-3 Typical overload limits
Operating mode
Heavy Duty overload
Motor rated current = drive rated
current
Heavy duty operating mode
The thermal protection is set to protect force ventilated induction motors and permanent magnet servo motors by default. If the application uses a
self ventilated (TENV/TEFC) induction motor and increased thermal protection is required for speeds below 50 % base speed, then this can be
enabled by setting Low Speed Thermal Protection Mode (B44) = On (1).
2
Operation of motor I
t protection
2
Motor I
t protection defaults to be compatible with:
•
Forced ventilation induction motors
•
Permanent magnet servo motors
Total Output Current (J22)
E300 Design Guide
Issue Number: 1
Electrical
Getting
User Menu A Commissioning
installation
started
Closed loop from cold Closed loop from 100 %
175 % for 40 s
as percentage of motor
rated current
2
I t protection operates in this region
100 %
70 %
Advanced
Parameters
175 % for 5 s
50 %
100 %
Diagnostics Optimization CT MODBUS RTU Technical Data
Open loop from cold
Open loop from 100 %
150 % for 60 s
Max. permissible
continuous
current
B44
= 0
B44
= 1
Motor speed as a
percentage of base speed
155 % for 8 s
13
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