Siemens 6SL38503UM114PA0Z, Operating Instructions & Installation Instructions

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3.3.2.7 Fans
The fan is mounted on the cabinet. The fan draws in air through the ventilation slots in the door
from the immediate vicinity of the cabinet. The fan blows the air radially into the ambient area.
A contactor and a motor protection switch protect the fan against overload.
3.3.2.8 Differential-pressure switch
The differential-pressure switch monitors the independent air cooling and the associated fans.
The operating range lies between 100 and 1000 Pa. The differential-pressure switch measures
the pressure drop across the heat sink elements. The pressure drop is then compared with the
set response threshold. When the fans are in operation and draw the required volumetric flow
through the heat sink elements, the response threshold must have been exceeded.
See also
Replacing the differential pressure monitor (Page 120)
3.3.2.9 Surge arresters
Overvoltages can occur when inductive loads are switched, for example, in the case of
transformer disconnections at no load. These overvoltages can pose a danger to the converter.
For indoor systems, surge arresters without spark gap are connected in a star configuration
between the phases to limit the overvoltages.
3.3.2.10 Door limit switches
Door limit switches monitor the doors or the cover of the power unit. When a door or a cover is
opened, the converter is switched off and the circuit breaker opened.
Note
Door limit switches are used for monitoring, but do not provide a protection function.
3.3.3 Principle of operation
3.3.3.1 Fuseless technology
The converter is of fuseless design. In the event of a fault, limiting of the overcurrent at the input
terminals should be ensured by an appropriate transformer design. In addition, the converter
requires matched circuit breakers with a tripping time of 80 ms. The closed-loop control system
triggers the circuit breakers. Each circuit breaker must be equipped with a fail-safe OFF contact
and an undervoltage coil.
Description
3.3 Power unit
SINAMICS GL150 6SL38503UM114PA0Z
34
Operating Instructions Rev.201910301420 MUSTER