Derating

Liquid-cooled SINAMICS S120 chassis format units are rated for an ambient temperature of 45 °C and installation altitudes up to 2000 m above sea level. At ambient temperatures > 45 °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.

Current derating as a function of the temperature of the cooling liquid ¹⁾

Current derating as a function of ambient temperature ¹⁾

¹⁾ The factors of the two curves must not be multiplied. The highest value in each case must be assumed for the purposes of calculation, so that the derating factor in the worst-case scenario is 0.9.

Permissible ambient temperature as a function of installation altitude

Voltage derating as a function of 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 tables list 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

¹⁾ This Motor Module has been specifically designed for loads demanding a high dynamic performance. The derating factor k_IGBT and the derating characteristic curves can be ignored (see section “Duty cycles” in the SINAMICS Low Voltage Engineering Manual).

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

²⁾ The Motor Module 6SL3325-1TG38-0AA3 is optimized for low overload; with an increased pulse frequency, the derating factor is higher than for the Motor Module 6SL3325-1TG38-1AA3.

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

³⁾Higher frequencies on request. For further information see https://support.industry.siemens.com/cs/document/104020669

Pressure drop

Pressure drop for liquid-cooled built-in units in chassis format

The pressure drop characteristic curves are valid for water. If antifreeze is used, the characteristic curves typically shift to the left.

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

Overload capability

Liquid-cooled SINAMICS S120 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 the basis for a duty cycle of 110 % for 60 s or 150 % for 10 s.

Low overload

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

High overload

The following applies to the Motor Module 6SL3325-1TG41-6AP3:
This Motor Module is particularly suited to high breakaway torques with applications such as drilling, mixers, centrifuges, and test bays. An additional duty cycle is required at output frequencies of 5 Hz to 10 Hz.
At output frequencies of 1 Hz to 5 Hz, the short-time current is 1900 A for 5 s.

High overload for Motor Module 6SL3325-1TG41-6AP3

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