Beijer Electronics BFI-P2 V1.21 - Manual (Page 51)

User Guide Revision 1.121
www.beijerelectronics.com
51
10.4. 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
•
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
10.4.1. Derating for Ambient Temperature
Enclosure Type Maximum Temperature
Without Derating
Derate by Maximum Permissable
IP20 50°C / 122°F N/A 50°C
IP40 40°C / 104°F N/A 40°C
IP55 40°C / 104°F 1.5% per °C (1.8°F) 50°C
IP66 40°C / 104°F 2.5% per °C (1.8°F) 50°C
10.4.2. Derating for Altitude
Enclosure Type Maximum Altitude
Without Derating
Derate by Maximum Permssable
(UL Approved)
Maximum Permssable
(Non‐UL Approved)
IP20 1000m / 3281ft 1% per 100m / 328 ft 2000m / 6562 ft 4000m / 13123 ft
IP40 1000m / 3281ft 1% per 100m / 328 ft 2000m / 6562 ft 4000m / 13123 ft
IP55 1000m / 3281ft 1% per 100m / 328 ft 2000m / 6562 ft 4000m / 13123 ft
IP66 1000m / 3281ft 1% per 100m / 328 ft 2000m / 6562 ft 4000m / 13123 ft
10.4.3. Derating for Swicthing Frequency
Switching Frequency (Where available)
Enclosure Type 4kHz 8kHz 12kHz 16kHz 24kHz 32kHz
IP20 N/A N/A 20% 30% 40% 50%
IP40 N/A TBC TBC TBC TBC TBC
IP55 N/A 10% 10% 15% 25% N/A
IP66 N/A 10% 25% 35% 50% 50%
10.4.4. Example of applying Derating Factors
A 4kW, IP66 drive is to be used at an altitude of 2000 metres above sea level, with 12kHz 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, 12kHz, 25% derating
9.5 Amps x 75% = 7.1 Amps
Now, apply the derating for higher ambient temperature, 2.5% per °C above 40°C = 5 x 2.5% = 12.5%
7.1 Amps x 87.5% = 6.2 Amps
Now apply the derating for altitude above 1000 metres, 1% per 100m above 1000m = 10 x 1% = 10%
7.9 Amps x 90% = 5.5 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.