Reduced Output Current Due To Speed; Figure 36: Derating Factor "K" For Motor Installation (Self-Ventilated) - nord NORDAC FLEX SK 200E Series User Manual

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8.4.6 Reduced output current due to speed

Size 1 – 3 devices are designed such that the waste heat that occurs can only be given off via the
housing in sufficient quantities if the variable frequency drive with motor installation is also cooled by
an air flow. If this air flow is generated by a self-ventilated motor (impeller mounted on the motor
shaft), the strength of the air flow then depends on the motor speed. This means that as the motor
speed reduces, so does the air flow. Depending on the variable frequency drive and the speed that is
present, appropriate restrictions in the possible output power (S1 operation) must be taken into
consideration.
This restriction can be determined on the basis of the following graph. However, it must be taken into
consideration that the result that is determined can only be a rough estimate, since various influential
factors such as specific variable frequency drive/motor combinations cannot also be taken into
consideration. Please refer to catalog
The "k" factor of the following graph must be multiplied by the nominal data of the variable frequency
drive concerned, and therefore results in the possible continuous current or the possible continuous
output in S1 operation.
Example:
SK 200E-401-340 A, I
rated
x k  I = 8.9 A x 0.7 = 6.2 A in S1 operation
I = I
rated
All device sizes 1 to 3 except the devices from ( 2 )
1 =
SK 2xxE-111-323-A, SK 2xxE-221-323-A, SK 2xxE-401-323-A,
2 =
SK 2xxE-221-340-A, SK 2xxE-401-340-A, SK 2xxE-751-340-A

Figure 36: Derating factor "k" for motor installation (self-ventilated)

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BU 0200 en-US-4920
G4014 for more information.
= 8.9 A, f_out: 20 Hz  k=0.7
8 Additional information
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