Derating Information - Invertek Drives Eco Optidrive Series User Manual

12.5. Derating Information

Derating of the drive maximum continuous output current capacity is require 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
12.5.1. Derating for Ambient Temperature
Enclosure Type
IP20
IP55
IP66
12.5.2. Derating for Altitude
Enclosure Type
IP20
IP55
IP66
12.5.3. Derating for Switching Frequency
Enclosure Type Frame Size
IP66 2
3
IP55 4
5
6
7
IP20 8
12.5.4. 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.
From the table above, we can see that the rated current of the drive is 9.5 Amps at 40°C,
Firstly, apply the switching frequency derating (if any), 16 kHz, 0% derating
Now, apply the derating for higher ambient temperature, 2.5% per °C above 40°C = 5 x 2.5% = 12.5%
9.5 Amps x 87.5% = 8.3 Amps
Now apply the derating for altitude above 1000 metres, 1% per 100m above 1000m = 10 x 1% = 10%
8.3 Amps x 90% = 7.5 Amps continuous current available.
If the required motor current exceeds this level, it will be necessary to either
-
Reduce the switching frequency selected
-
Use a higher power rated drive and repeat the calculation to ensure sufficient output current is available.
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Optidrive Eco User Guide Revision 2.01
Maximum Temperature
Without Derating
50°C / 122°F
40°C / 104°F
40°C / 104°F
Maximum Altitude
Without Derating
1000m / 3281ft 1% per 100m / 328 ft.
1000m / 3281ft 1% per 100m / 328 ft.
1000m / 3281ft 1% per 100m / 328 ft.
4kHz 8kHz 10kHz
N/A N/A 0%
N/A N/A 0%
N/A N/A 0%
N/A N/A 0%
0% 10% N/A
0% 10% N/A
0% N/A N/A
Derate by
N/A
1.5% per °C (1.8°F)
2.5% per °C (1.8°F)
Derate by
Switching Frequency (Where available)
12kHz 14kHz 16kHz
0% 0% 0%
0% 0% 0%
0% 0% 0%
0% 0% 0%
10% N/A 15%
10% N/A 15%
N/A N/A N/A
Maximum Permissible
50°C / 122°F
50°C / 122°F
50°C / 122°F
Maximum
Permissible
4000m / 13123 ft.
4000m / 13123 ft.
4000m / 13123 ft.
18kHz 20kHz 24kHz
TBC TBC N/A
TBC TBC N/A
TBC TBC N/A
TBC TBC N/A
N/A N/A 25%
N/A N/A 25%
N/A N/A N/A
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32kHz
N/A
N/A
N/A
N/A
N/A
N/A
N/A