Siemens MICROMASTER 411 - Manual (Page 119)

Issue 03/01 10 Engineering Information
MICROMASTER 411 & COMBIMASTER 411 Operating Instructions
6SE6400-5CA00-0BP0 119
10.1.4 I 2 t Performance
When the motor is running at low speed and high load, the built-in cooling fan may
not provide enough cooling and the motor may overheat.
Parameter P0610 allows
a frequency dependent I 2 t limit to be enabled to protect the motor.
When the inverter is operating in the region above the selected curve (i.e. at low
frequency and high current), a timer is started, and after some time, (based on the
current, the motor size and previous operating history), the inverter will trip or
reduce output frequency.
Trip or reduction of output frequency will depend on the
parameter setting.
10.1.5 Internal Overtemperature
Under normal circumstances, the inverter will not overheat. The heatsink maintains
the inverter at normal operating temperature. Careful consideration when mounting
the inverter will ensure adequate ventilation and reduce the likelihood of
overheating.
Check to see that airflow remains unrestricted. There should be a
minimum clearance of 100 mm free space around the Inverter.
Heatsink temperature is monitored using a PTC resistor and the inverter will trip if
the maximum temperature is exceeded.
If the inverter persistently trips, you should
check for high ambient temperature or blocked airflow.
You can verify heatsink temperature by displaying Parameter r0037.
Units are
given in degrees Celsius ( o C).
10.1.6 Overvoltage and Trip Levels
The inverter will protect itself from both supply overvoltage and undervoltage. Trip
levels are shown in Table 10-2. Internal overvoltage can occur during braking
where internal voltages are forced high by energy from an external load.
Table 10-2 Trip Levels
Input
Supplies
Undervoltage
trip levels
Overvoltage
trip levels
3 AC 400 V 410 V 820 V
When output pulses are disabled from the inverter an undervoltage trip will not
occur.
An overvoltage trip will occur at any time when the overvoltage threshold is
exceeded.
CAUTION
Check to ensure you have matched the input supply to the inverter. If the supply
voltage is too high, you may damage the inverter even if it trips.