Derating

Liquid-cooled SINAMICS S120 Cabinet Modules are rated for an ambient temperature of 45 °C and installation altitudes up to 2000 m above sea level and a plant-side raw water temperature of 38 °C (<IP55) or 33 °C (IP55). At ambient temperatures > 45 °C and a plant-side raw water temperature > 38 °C (<IP55) or 33 °C (IP55), 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.

The intake temperatures in the plant/system side raw water circuit must always be at least 7 K below the intake temperatures in the converter-side deionized water circuit. This ensures that the cooling power of the Heat Exchanger Module of the deionized water circuit, specified in the technical data, can be dissipated to the raw water circuit.

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

Current derating as a function of the temperature of the cooling liquid in the converter-side deionized water circuit ¹⁾

Current derating as a function of ambient temperature ¹⁾

¹⁾ The factors of the two derating 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 depending on 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 data.

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

The following table lists the rated output currents of the Motor Modules with pulse frequency set at 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

¹⁾ The Motor Module 6SL3725-1TG38-0AA3 is optimized for low overload; with an increased pulse frequency, the derating factor is higher than for the Motor Module 6SL3725-1TG38-1AA3.

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

¹⁾ Higher frequencies on request.

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. For 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

Motor Modules can be configured on the basis of different base load currents.

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 load cycle of 150 % for 60 s or 160 % for 10 s.

High overload

Basic Line Connection Modules and Active Line Connection 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