Derating data, chassis format

Air-cooled SINAMICS G120 chassis format units and the associated system components are rated for an ambient temperature of 40 °C and installation altitudes up to 2000 m above sea level.

At ambient temperatures > 40 °C, the output current must be reduced. Ambient temperatures above 55 °C are not permissible.

At installation altitudes > 2000 m above sea level, it must be taken into account that the air pressure, and therefore air density, decreases as the height increases. As a consequence, the cooling efficiency and the insulation capacity of the air also decrease.

Due to the reduced cooling efficiency, it is necessary, on the one hand, to reduce the ambient temperature and on the other hand, to reduce the heat loss in the built-in unit by reducing the output current, whereby ambient temperatures lower than 40 °C may be offset to compensate.

The following table lists the permissible output currents depending on the installation altitude and ambient temperature. The specified values already include a permitted compensation in respect of installation altitude and ambient temperatures < 40 °C (temperature at the air intake of the built-in unit).

The values apply under the precondition that a cooling air flow through the devices is guaranteed as specified in the technical specifications.

As additional measure for installation altitudes from 2000 m up to 5000 m, an isolating transformer is required in order to reduce transient overvoltages according to EN 60664‑1.
For additional information, please refer to the SINAMICS Low Voltage Engineering Manual.

Current derating factors for SINAMICS S120 chassis units as a function of the ambient/air intake temperature and the installation altitude

Current derating for Power Modules and Motor Modules in chassis format as a function of the pulse frequency

To reduce motor noise or to increase output frequency, the pulse frequency can be increased relative to the factory setting (1.25 kHz or 2 kHz). When the pulse frequency is increased, the derating factor of the output current must be taken into account. This derating factor must be applied to the currents specified in the technical specifications.

For additional information, please refer to the SINAMICS Low Voltage Engineering Manual.

The following table lists the rated output currents of the SINAMICS S120 Power Modules and Motor Modules with pulse frequency set in the factory as well as the current derating factors (permissible output currents referred to the rated output current) for higher pulse frequencies.

Derating factor of the output current as a function of the pulse frequency for units with a rated pulse frequency of 2 kHz

Derating factor of the output current as a function of the pulse frequency for units with a rated pulse frequency of 1.25 kHz

The following tables list the maximum achievable output frequency as a function of the pulse frequency:

Maximum output frequencies achieved by increasing the pulse frequency in Vector mode

Maximum output frequencies achieved by increasing the pulse frequency in Servo mode

¹⁾ Higher frequencies on request. For further information, see https://support.industry.siemens.com/cs/document/104020669

Overload capability

SINAMICS S120 chassis units have an overload reserve, e.g. to handle breakaway torques. If larger surge loads occur, this must be taken into account in the configuration. For drives with overload requirements, the appropriate base-load current must, therefore, be used as a basis for the required load.

The permissible overload levels are valid under the prerequisite that the drive units are operated with their base-load current before and after the overload condition based on a duty cycle duration of 300 s.

Another precondition is that the Power Modules or the Motor Modules are operated at their factory-set pulse frequency at output frequencies > 10 Hz.

For temporary, periodic duty cycles with high variations of load within the duty cycle, the relevant sections of the SINAMICS Low Voltage Engineering Manual must be observed.

Power Modules and Motor Modules

The base-load current for a low overload I_L is based on a duty cycle of 110 % for 60 s or 150 % for 10 s.

Low overload

The base-load current for a high overload I_H is based on a duty cycle of 150 % for 60 s or 160 % for 10 s.

High overload

Line Modules

The base-load current for a high overload I_H DC is the basis for a duty cycle of 150 % for 60 s or I_max DC for 5 s.

High overload