REXROTH EcoDrive Cs - Inrush Current Impulse

6-6 Mains and Supply Voltage Connection Rexroth EcoDrive Cs Drives
DOK-ECODR3-DKC**.3-CS*-PR02-EN-P
Inrush Current Impulse
When the power supply (mains voltage) is switched on, the DC bus
capacitors are first charged via the softstart resistance. This causes a
current impulse when switching on that falls off at increasing DC bus
voltage.
Softstart
N1
inE
R
2*U
=I
∑
= EinGesamtEin II
IEin: inrush current of unit in A
I
EinGesamt: total inrush current in A (value relevant for fusing)
U
N1: mains input voltage
R
Softstart: softstart resistance of unit (see relevant technical data)
Fig. 6-7: Computing inrush current
Note: To compute the inrush current take all the units connected to
the mains voltage into account.
4 DKC02.3-W0012 drive controllers are connected to a mains connection.
R
Softstart
= 4.7 Ohm (see technical data)
U
N1
= 264 V (max. allowed mains input voltage)
I
EIN
= 79.4 A
 total inrush current: I
EinGesamt
= 317.6 A
Note: This inrush current, however, is only of short duration,
because the time constant of the RC element with
T = R
Softstart
x C
Zwischenkreis
is within a range of milliseconds
(T = 2...4 ms)!
For 100 W, 200 W, and 400 W drive controllers: To reduce the inrush
current you can connect our accessories
SUP-E05-DKC*CS-SURGEP to
the drive controller at terminal X2 (see chapter 10, page 10-18). This
accessories contains an NTC thermistor (33 Ohm at 25 °C; 19.6 Ohm at
40 °C) to reduce the inrush current.
CAUTION
Risk of damage by heat!
⇒ 400 W drive controllers (DKCxx.x-012) that are
operated with SUP-E05-DKC*CS-SURGEP may
only be operated with a maximum power of 70%.
With higher load the NTC thermistor gets too hot.
Note: For 750 W drive controllers the SUP-E05-DKC*CS-SURGEP
is not suitable.
Computing Inrush Current
Impulse
Numerical example
Reducing inrush current
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