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4.2 CALCULATION OF OVERLOAD
Using table above it's possible to calculate permissible overloads for the different electrical sizes of inverters
We use a 4kVA open version inverter and we want to know permissible time to supply 6kVA without
alarms:
6000/230 = 26Arms
26Arms-18.7Arms = 7.3Arms over the limit
20A*s = 7.3*t
T = 2.74s = maximum time @ 6kVA
We use a 15kVA box version inverter and we want to know maximum power overload permissible in 2s:
Imax = Overload rms
Imax-66Arms = over the limit
75A*s = (Imax-66)*2 A*s
Imax = (75+132)/2 = 103.5Arms
Overload, short circuit and over temperature have different values depending on the electrical size of the invert-
er, in particular:
Type
4kVA open
I*t = 20A*s over 18.7Arms
4kVA box
I*t = 20A*s over 18.7Arms
6kVA open
I*t = 30A*s over 28Arms
6kVA box
I*t = 30A*s over 28Arms
10kVA box
I*t = 50A*s over 47Arms
15kVA box
I*t = 75A*s over 66Arms
20kVA box
I*t = 100A*s over 93Arms
APPLICABLE STANDARDS
Low voltage directive
Power electronics safety
EMC directive
Emission
Immunity
Harmonics
Overload
Current limited @ 50Apk for 600ms
Current limited @ 50Apk for 600ms
Current limited @ 70Apk for 600ms
Current limited @ 70Apk for 600ms
Current limited @ 123Apk for 600ms
Current limited @ 185Apk for 600ms
Current limited @ 246Apk for 600ms
Short circuit
LVD (2006/95/EC)
EN50178
EMC (2004/108/EC)
EN55022
EN61000-6-1
EN61000-3-2 <16A; EN61000-3-12 >16A
24
Over temperature
70°C
70°C
70°C
70°C
85°C
85°C
85°C
Inverter manual rev.01/19
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