Schaffner FN5420, User And Installation Manual

Page: 17 / 54

Schaffner Group
User and Installation Manual
Output filter FN5420 and RWK5420
schaffner.com 16/52
2.4 Derating
Sine wave filter FN5420 and dv/dt reactor RWK5420 might be applied with derated current when it is
applied beyond specification. Below is the calculation of temperature derating and motor frequency de-
rating.
2.4.1 Temperature derating
All sine wave filter FN5420 series and dv/dt reactor RWK5420 series are able to operate at rated cur-
rent up to an ambiante temperature of 45°C (measured next to the device, i.e. inside a cabinet). It is
possible to use the filter and reactor above this limit, but a derating must be applied on the maximum
current going through the filter.
The derating calculation is as follow:
𝐼𝐼
𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑
= 𝐼𝐼
𝑛𝑛𝑛𝑛𝑛𝑛
�
𝑇𝑇
𝑛𝑛𝑑𝑑𝑚𝑚
− 𝑇𝑇
𝑑𝑑𝑛𝑛𝑎𝑎
𝑇𝑇
𝑛𝑛𝑑𝑑𝑚𝑚
− 𝑇𝑇
𝑛𝑛𝑛𝑛𝑛𝑛
𝐼𝐼
𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑
= 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑤𝑤𝑤𝑤𝑐𝑐ℎ 𝑑𝑑𝑐𝑐𝑐𝑐𝑑𝑑𝑐𝑐𝑤𝑤𝑐𝑐𝑑𝑑
𝐼𝐼
𝑛𝑛𝑛𝑛𝑛𝑛
= 𝑐𝑐𝑛𝑛𝑛𝑛𝑤𝑤𝑐𝑐𝑑𝑑𝑛𝑛 𝑐𝑐𝑑𝑑𝑐𝑐𝑐𝑐𝑑𝑑 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐
𝑇𝑇
𝑛𝑛𝑛𝑛𝑛𝑛
= 𝑐𝑐𝑛𝑛𝑛𝑛𝑤𝑤𝑐𝑐𝑑𝑑𝑛𝑛 𝑐𝑐𝑐𝑐𝑛𝑛𝑡𝑡𝑐𝑐𝑐𝑐𝑑𝑑𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 45° 𝐶𝐶
𝑇𝑇
𝑑𝑑𝑛𝑛𝑎𝑎
= 𝑑𝑑𝑛𝑛𝑎𝑎𝑤𝑤𝑐𝑐𝑐𝑐𝑐𝑐 𝑐𝑐𝑐𝑐𝑛𝑛𝑡𝑡𝑐𝑐𝑐𝑐𝑑𝑑𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 ( 𝑛𝑛𝑑𝑑𝑚𝑚𝑤𝑤𝑛𝑛𝑐𝑐𝑛𝑛 𝑐𝑐ℎ𝑑𝑑𝑐𝑐 𝑐𝑐𝑑𝑑𝑐𝑐 𝑛𝑛𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑤𝑤𝑐𝑐 𝑑𝑑𝑡𝑡𝑡𝑡𝑛𝑛𝑤𝑤𝑐𝑐𝑑𝑑𝑐𝑐𝑤𝑤𝑛𝑛𝑐𝑐 ), must be ≥ 𝑇𝑇
𝑛𝑛𝑛𝑛𝑛𝑛
𝑇𝑇
𝑛𝑛𝑑𝑑𝑚𝑚
= 𝑛𝑛𝑑𝑑𝑚𝑚𝑤𝑤𝑐𝑐𝑛𝑛 𝑑𝑑𝑛𝑛𝑛𝑛𝑛𝑛𝑤𝑤𝑐𝑐𝑑𝑑 𝑐𝑐𝑐𝑐𝑛𝑛𝑡𝑡𝑐𝑐𝑐𝑐𝑑𝑑𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑓𝑓𝑛𝑛𝑐𝑐 𝑐𝑐ℎ𝑐𝑐 𝑓𝑓𝑤𝑤𝑛𝑛𝑐𝑐𝑐𝑐𝑐𝑐 𝑛𝑛𝑐𝑐 𝑐𝑐𝑐𝑐𝑑𝑑𝑐𝑐𝑐𝑐𝑛𝑛𝑐𝑐 ( 𝑠𝑠𝑐𝑐𝑐𝑐 𝑎𝑎𝑐𝑐𝑛𝑛𝑛𝑛𝑤𝑤 )
Please note that the maximum allowed temperature is a fixed value from the product specification, but
it is not the same depending on the filter size (smaller filter have a higher tolerance).
Filter type Maximum allowed ambient temperature (T
max
)
FN5420 sizes 2.3A to 18A 100°C
FN5420 sizes 26A to 1000A 70°C
RWK5420 sizes 2.3A to 18A 100°C
RWK5420 sizes 26A to 1000A 100°C
Note that you can use a spreadsheet to easily calculate the result as follow:
I
nom
[A] 75
T
amb
[°C] 50
T
nom
[°C] 45
T
max
[°C] 70
I
derated
[A] Formula
Formula : =Inom*SQRT((Tmax-Tamb)/(Tmax-Tnom))