Derating

For some modules of the KE/KW drive system , a derating factor need to be considered when the modules are operated with air cooling systems. The following derating factors reduces the rated current and also the rated power specified for the devices at rated voltage. The rated data can be found in the chapter technical data of the documentation PDK_028932_KEKW_Hardware.

The derating increases in case of KES operation or with higher DC bus voltage, i.e. the derating factor decreases further.

The derating factors depend on the revision level of the air cooling system and improved if the firmware of the converter works with the temperature model. (See tables following.)

The power losses are based on the operating point:

KW, KWD, KWZ:	U_{DC bus} = 540 VDC, U_Motor = 3 x 350 VAC, f_PWM = 8 kHz
KE:	U_{power supply} = 3 x 400 VAC, U_Z = 540 VDC
KES:	U_{power supply} = 3 x 400 VAC, U_Z = 720 VDC, f_PWM = 8 kHz

Example:

An inverter with rated data 20 kW output power and 33 A output current has a derating of 0.8 for air cooling.

The valid output power with air cooling is:

20 kW x 0.8 = 16 kW

At rated output voltage the valid current is 33 A x 0.8 = 26.4 A.

For compact power supplies and compact inverters with a module width of 425 mm, cold plates KW-CP680 ( AMK part no. O708), KW-CP510 (AMK part no. O706) respectively KW-CP510R ( AMK part no. O707) must be exclusively used with a revision from 2.03 on!