Beijer Electronics Frequency Inverter BFI-H3
KI00363D 2021-07
7 (32)
4.6 Derating Information
Derating of the drive maximum continuous output current capacity is required when:
Operating at ambient temperature in excess of 40°C/104°F (IP55 & IP66) or 50°C / 122°F
(IP20).
Operating at Altitude in excess of 1000m/ 3281 ft.
Operation with Effective Switching Frequency higher than the minimum setting.
The following derating factors should be applied when operating drives outside of these
conditions.
Derating for Ambient Temperature
Enclosure Type
Maximum Temperature
Without Derating
Derate by
Maximum
Permissible
IP20
50°C / 122°F
N/A
50°C / 122°F
IP20 Frame Size5
35°C / 95°F
1.1% per °C (1.8°F)
50°C / 122°F
IP55
40°C / 104°F
1.5% per °C (1.8°F)
50°C / 122°F
IP66
40°C / 104°F
2.5% per °C (1.8°F)
50°C / 122°F
Derating for Altitude
Enclosure Type
Maximum Height Above Sea
Level Without Derating
Derate by
Maximum
Permissible
IP20, IP55 and IP66
1000m / 3281ft
1% per 100m / 328 ft
4000m / 13123 ft
Derating for Switching frequency
Example of Applying Derating Factors
A 4kW, IP66 drive is to be used at an altitude of 2000 metres above sea level, with 16 kHz switching
frequency and 45°C ambient temperature. Rated current of the drive is 9.5 Amps at 40°C,
-
16 kHz: Switching frequency derating, for IP66 Size2 is 0% derating.
-
45°C: Derating for higher ambient temperature, (45-40) * 2.5% per °C = 12.5%
-
2000 m: Derating for altitude, 2000m, (2000-1000)/100)*1,0 = 10%
Means BFI can deliver 9,5 *0,875*0,9= 7,5 A.
If the required motor current exceeds this level, it will be necessary to either:
Reduce the switching frequency selected or use a higher power rated drive and repeat the calculation
to ensure sufficient output current is available.
Enclosure
Type
Switching Frequency
Frame
Size
4
kHz
8
kHz
10
kHz
12
kHz
14
kHz
16
kHz
18
kHz
20
kHz
24
kHz
32
kHz
IP66
2
N/A
N/A
0 %
0 %
0 %
0 %
0 %
0 %
N/A
N/A
3
N/A
N/A
0 %
0 %
0 %
6 %
N/A
N/A
N/A
N/A
IP55
4
N/A
N/A
0 %
0 %
12 %
23 %
33 %
41 %
N/A
N/A
5
N/A
N/A
0 %
0 %
11 %
23 %
36 %
42 %
N/A
N/A
6
0 %
16 %
N/A
28 %
N/A
39 %
N/A
N/A
N/A
N/A
7
0 %
12 %
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
IP20
2
N/A
N/A
0 %
14 %
23 %
32 %
37 %
43 %
N/A
N/A
3
N/A
N/A
0 %
2 %
13 %
19 %
25 %
35 %
N/A
N/A
4
N/A
N/A
0 %
15 %
13 %
39 %
52 %
62 %
N/A
N/A
5
N/A
N/A
0 %
3 %
9 %
14 %
19 %
24 %
N/A
N/A
6
0 %
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
8
0 %
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
