Siemens MICROMASTER 411 - Manual (Page 137)

Issue 03/01 10 Engineering Information
MICROMASTER 411 & COMBIMASTER 411 Operating Instructions
6SE6400-5CA00-0BP0 137
10.5 Thermal Protection and Automatic De-rating
The MICROMASTER 411/COMBIMASTER 411 has comprehensive hardware and
software thermal protection.
Hardware: Fitted to the heatsink is a PTC resistor that will cause the inverter to
trip if the temperature reaches 95 ° C.
Software: When the heatsink reaches a temperature of within 5ºC of the trip
level, the switching frequency and output frequency of the inverter will
both be reduced. This reduces the Inverter losses and current and
attempts to prevent an overtemperature trip.
It is possible to prevent this reduction and select an immediate trip if
desired. See parameters P0290, P0292 for further details.
Instead of this reduction an immediate switching off also can be
selected. More information sie parameters P0290 and P0292
The inverter is further protected by an Inverter I
2 t calculation that
determines how hot the Insulated Gate Bipolar Transistors (IGBTs)
are and will reduce the current limit (P0640) when this calculation
reaches 95%. (User defined in P0294). If the I
2 t continues to rise to
100% an Inverter I 2 t trip will occur (F0005).
Overtemperature in the inverter is usually caused by a high ambient
temperature or blocked convection.
10.6 Operation from Unearthed Supplies
The MICROMASTER 411 cannot be used on unearthed input supplies.
10.7 Lifetime of Inverters
When the inverters are used in conjunction with Siemens motors (1LA7 and 1LA9)
the liftetime of the inverter is >= 20,000 hours.