Actual signals and parameters
92
DTC The protection is based on the calculated motor thermal model. The
following assumptions are used in the calculation:
- The motor is at the estimated temperature (value of 01.37 MOTOR
TEMP EST saved at power switch off) when the power is switched
on. With the first power switch on, the motor is at the ambient
temperature 86 °F (30 °C).
- The motor temperature increases if it operates in the region above
the load curve and decreases if it operates below the curve.
- The motor thermal time constant is an approximate value for a
standard self-ventilated squirrel-cage motor.
It is possible to fine tune the model by 30.07 MOTOR LOAD CURVE.
Note: The model cannot be used with high power motors (99.06
MOTOR NOM CURRENT is higher than 800 A).
WARNING! The model does not protect the motor if it does
not cool properly due to dust and dirt.
1
USER MODE The protection is based on the user-defined motor thermal model and
the following basic assumptions:
- The motor is at the estimated temperature (value of 01.37 MOTOR
TEMP EST saved at power switch off) when the power is switched
on. With the first power switch on, the motor is at the ambient
temperature 86 °F (30 °C).
- The motor temperature increases if it operates in the region above
the motor load curve and decreases if it operates below the curve.
The user-defined thermal model uses the motor thermal time constant
(30.06 MOTOR THERM TIME) and the motor load curve (30.07
MOTOR LOAD CURVE, 30.08 ZERO SPEED LOAD and 30.09
BREAK POINT). User tuning is typically needed only if the ambient
temperature differs from the normal operating temperature specified
for the motor.
WARNING! The model does not protect the motor if it does
not cool properly due to dust and dirt.
2
No. Name/Value Description FbEq
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