Functions
8.22 Thermal motor protection and overload responses
Control Units CU240S
Operating Instructions, 11/2006, A5E00766042B AA
8-153
The ambient temperature P0625 is another important parameter which influences the
precision of the thermal model.
8.22.2 Motor Temperature Identification after Restart
Data
Parameter range: P0621 … r0623
Warnings: –
Faults: –
Function chart number: –
Description
The thermal motor model can be used to calculate the motor temperature. Not only this it
can be also used to optimize the control loops for closed-loop vector control and for
temperature monitoring. A KTY84 sensor is then no longer required for temperature sensing.
After the power supply (24 V) has been powered-down, the motor temperature - internally
calculated using the thermal motor model - is no longer available. The model then starts with
the ambient temperature value (P0625).
If the "Determining the motor temperature after motor start" function is active, the motor
temperature is detected by measuring the current after magnetization and the thermal motor
model is then pre-assigned this value.
Parameter P0621 is used to select when the function is active:
P0621 = 0: The function is de-activated. The thermal motor model then uses the ambient
temperature value (P0625).
P0621 = 1: The motor temperature is determined once when the motor first starts after the
power supply has been switched-in. This setting is used for standard motors.
P0621 = 2: For this setting, a new temperature measurement is carried-out each time the
motor starts. This technique is practical for motors whose thermal behavior differs from
standard motors. In these cases, it is possible that the thermal model is too inaccurate and
would supply larger deviations.
Note
If a KTY84 sensor is being used and is functional, then the temperature of the sensor is used
in all settings of parameter P0621. In this case, the temperature is not measured using the
stator resistance.
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