1 DA1 device series
1.8 Output reduction (derating)
DA1 Variable Frequency Drives 11/16 MN04020005Z-EN www.eaton.com 33
Examples showing how to apply derating factors
4 kW motor (400 V, 8.5 A), installation altitude of 2,000 m above sea level,
ambient temperature of 42 °C, switching frequency of 12 kHz.
a)
Selected variable frequency drive: DA1-349D5FB-A20C, rated operational
current of 9.5 A, switching frequency of 8 kHz (default setting).
Required derating factors:
• For the 12 kHz switching frequency: 20%
• For the 2,000 m installation altitude: 10% (1% per 100 m above 1,000 m,
2,000 m - 1,000 m = 1,000 m, 1,000 m/100 m = 10)
• For the 42 °C ambient temperature: None
(not needed for DA1-349D5FB-A20C, IP20 degree of protection)
9.5 A - 20 % - 10 % = (9.5 x 0.8 x 0.9) A = 6.84 A
The DA1’s permissible continuous rated operational current of 6.84 A is
lower than the motor’s required rated operational current (8.5 A).
Reducing the pulse frequency to 8 kHz will make it possible to operate the
motor continuously at an altitude of 2,000 m (9.5 A - 10% = 8.55 A).
b)
Selected variable frequency drive: DA1-34014FB-B55C, rated operational
current of 14 A.
Required derating factors:
• For the 12 kHz switching frequency: 10 %
• For the 2,000 m installation altitude: 10 % (1 % per 100 m above
1,000 m,
2,000 m - 1,000 m = 1,000 m, 1,000 m/100 m = 10)
• For the 42 °C ambient temperature: 3%
(1.5 % per kelvin, 42 °C - 40 °C = 2 K, IP55 degree of protection).
14 A - 10 % - 10 % - 3 % = (14 x 0.9 x 0.9 x 0.97) A= approx. 11 A
The DA1-34014FB-B55C variable frequency drive meets the necessary
operating conditions.
￫
Use a variable frequency drive belonging to a higher output
class and repeat the calculations in order to ensure that a
sufficiently high output current will be available continuously.
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