Derating data for the chassis format

SINAMICS G120 Cabinet Modules 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 of > 40 °C, the output current must be reduced. Ambient temperatures above 50 °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, to lower heat loss in the Cabinet Module by reducing the output current, whereby ambient temperatures lower than 40 °C may be offset to compensate.

The following table specifies the permissible output currents as a function of the installation altitude and ambient temperature for the various degrees of protection (the permissible compensation between installation altitude and the ambient temperatures < 40 °C – air intake temperature at the entry to the Cabinet Module – has been taken into account in the specified values).

The values apply under the precondition that it is ensured that the cooling air, as specified in the technical specifications, flows through the units as a result of the cabinet arrangement.

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

Current derating factors for Cabinet Modules as a function of the ambient/air intake temperature, the installation altitude and the degree of protection

Current derating for SINAMICS S120 Motors Modules, 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. 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 about this, please refer to the SINAMICS Low Voltage Engineering Manual.

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

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

The following table lists the maximum achievable output frequency as a function of the pulse frequency:

Overload capability

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

Permissible overload assumes that the drive converter is operated at its base-load current before and after the overload occurs, based on a duty cycle duration of 300 s.

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.

Motor Modules in chassis format

Motor Modules with power units in chassis format can be configured on the basis of different base-load currents.

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.

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.

Line Modules in chassis format

The base-load current for a high overload I_{H DC} is based on a duty cycle of 150 % for 60 s or I_{max DC} for 5 s.