Vacon 100X series, Applications Manual

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Parameters vacon • 88
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6
6.1.10.2 Group 3.9.2: Motor Therm Prot
The motor thermal protection is to protect the motor from overheating. The AC 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 capac-
ity. 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 IT spec-
ifies the load current above which the motor is overloaded. This current limit is a function of
the output frequency.
The thermal stage of the motor can be monitored on the control keypad display. See chapter
6.1.
NOTE! If you use long motor cables (max. 100m) together with small drives (
≤
1.5
kW) the motor current measured by the drive can be much higher than the actual
motor current due to capacitive currents in the motor cable. Consider this when
setting up the motor thermal protection functions.
CAUTION! The calculated model does not protect the motor if the airflow to the
motor is reduced by blocked air intake grill. The model starts from zero if the
control board is powered off.
Table 73. Motor thermal protection settings
Code Parameter Min Max Unit Default ID Description
P3.9.2.1 Motor Therm Prot 0 3 2 704
0 = No action
1 = Alarm
2 = Fault (Stop according to
stop mode)
3 = Fault (Stop by coasting)
If available, use the motor
thermistor to protect the
motor. Choose then value 0
for this parameter.
P3.9.2.2 MotAmbient Temp -20.0 100.0 °C 40.0 705 Ambient temperature in °C
P3.9.2.3 ZeroSpeedCooling 5.0 150.0 % Varies 706
Defines the cooling factor at
zero speed in relation to the
point where the motor is run-
ning at nominal speed with-
out external cooling.
P3.9.2.4 ThermTimeConst 1 200 min Varies 707
The time constant is the time
within which the calculated
thermal stage has reached
63% of its final value.
P3.9.2.5 MotThermLoadbil 10 150 % 100 708
Motor thermal Loadability
states how much the motor
can be thermally loaded. E.g.
90% means that the motor
temperature will settle
around 100% when continuo-
sly running at 90% of nomi-
nal load.
13006.emf
13006.emf