34 • vacon
description of parameters
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Motor Faults parameters
Parameters 2.8.5—2.8.8, Motor thermal protection:
General
The motor thermal protection is to protect the motor from overheating. The Vacon drive is capable
of supplying higher than nominal current to the motor. If the load requires this high current there
is a risk that the motor will be thermally overloaded. This is the case especially at low frequencies.
At low frequencies the cooling effect of the motor is reduced as well as its capacity. If the motor is
equipped with an external fan the load reduction at low speeds is small.
The motor thermal protection is based on a calculated model and it uses the output current of the
drive to determine the load on the motor.
The motor thermal protection can be adjusted with parameters. The thermal current I
T
specifies
the load current above which the motor is overloaded. This current limit is a function of the output
frequency.
CAUTION!
The calculated model does not protect the motor if the airflow to the
motor is reduced by blocked air intake grill.
2.8.5
Motor thermal protection
0 = No response
1 = Warning
2 = Fault, stop mode after fault according to
3 = Fault, stop mode after fault always by coasting
If tripping is selected the drive will stop and activate the fault stage.
Deactivating the protection, i.e. setting parameter to 0, will reset the thermal stage of
the motor to 0%.
2.8.6
Motor thermal protection: Motor ambient temperature factor
When the motor ambient temperature must be taken into consideration, it is
recommended to set a value for this parameter. The value of the factor can be set
between –100.0% and 100.0% where –100.0% corresponds to 0
°
C and 100.0% to the
maximum running ambient temperature of the motor. Setting this parameter value to
0% assumes that the ambient temperature is the same as the temperature of the
heatsink at power-on.
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