User`s manual

200 • Vacon apfiff09 marine
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6
7.12.5 Motor Protection
CAUTION! The calculated model does not protect the motor if the airflow to the
motor is reduced by blocked air intake grill.
The motor thermal protection is to protect the motor from overheating. The 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.
P2.12.5.1 Motor thermal protection reasponse ID704
Defines the response when the calculated temperature of the motor has reached 105 %
(monitoring signal).
0 = No response
1 = Warning
2 = Fault, stop mode after fault according to Stop Function
3 = Fault, stop mode after fault always by coasting
P2.12.5.2 Motor ambient temp. factor ID705
Defines the temperature factor for conditions where the motor is located.The factor can
be set between -100.0% 100.0%.
-100.0 % = 0°C,
0.0 % = 40°C,
100.0 % = 80°C
P2.12.5.3 Motor cooling factor at zero speed ID706
Defines the cooling factor at zero speed in relation to the point where the motor is
running at nominal speed without external cooling.
The default value is set assuming that there is no external fan cooling the motor. If an
external fan is used this parameter can be set to 90% (or even higher).
Note: The value is set as a percentage of the motor name plate data, (Nominal current of
motor), not the drive's nominal output current. The motor's nominal current is the
current that the motor can withstand in direct on-line use without being overheated.
Setting this parameter does not affect the maximum output current of the drive which is
determined by parameter Motor Current Limit alone.