1 DA1 device series
1.8 Output reduction (derating)
36
DA1 Variable Frequency Drives
08/18 MN04020005Z-EN
www.eaton.com
Examples showing how to apply derating factors
4 kW Motor (400 V, 8.5 A), installation altitude 2,000 m above sea level,
ambient temperature 42 °C, switching frequency 12 kHz.
a)
Selected frequency inverter: DA1-349D5FB-A20C:
Rated operational current 9.5 A, switching frequency 8 kHz (factory setting).
Required derating factors:
•
for the 12 kHz switching frequency:
20 %
•
for installation altitude 2,000 m:
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 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 frequency inverter: DA1-34014FB-B55C:
Rated operational current 14 A.
Required derating factors:
•
for the 12 kHz switching frequency:
10 %
•
for installation altitude 2,000 m:
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 ambient temperature 42 °C:
3 %
(1.5 % per Kelvin, 42 °C - 40 °C = 2 K, IP55 protection rating).
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.
