gefran SIEIDrive AVy Series Quick Start Up Manual page 88

N !
OTE
Formula for calculating the size of the external capacitors:
C , C [μF]
ext std
P [W]
SMPS
t [s]
Buff
U , U [V]
Buff min
Calculation example
An AVy4220 Drive is operated with an AC Input supply U
max. 1.5 s.
P 70 W
SMPS
U 400 V
Buff
C 1800 μF
std
Ch.5 88
When connecting the intermediate circuit terminals C and D the AC Input side must be
protected with superfast semiconductor fuses!
2 P
C =
ext
U = 400 V at U
Buff
U = 460 V at U
Buff
U = 250 V
min
t
Buff
U
min
2 . 70 W . 1.5 s . 10
=
C
ext
(400 V) 2 - (250 V)
t 10 6
SMPS Buff
- C
std
2 2
U - U
Buff min
= 400 V
LN
= 460 V
LN
= 400 V. A voltage failure buffer is required for
LN
1.5 s
250 V
6 m
F / F
- 1800mF = 2154 mF - 1800 mF = 354mF
2
AVy - HGB
fA018