Danfoss VACON 1000 Operating Manual page 25

Operating Guide | VACON® 1000
3.3.5 Start-up Cabinet
The start-up cabinet (+PSTC) is an option for the line-up systems. The start-up cabinet is used to magnetize the transformer and to
charge the DC-link capacitors of the power cells with lower current, avoiding the tripping of the primary protection (fuse or circuit
breaker), or physical damage to the power components. The main function of the start-up cabinet is to depress inrush currents that can
lead to a dip in the supply voltage:
A phase-shifting transformer with a large capacity can produce a magnetizing surge as high as 6–8 times the rated current of the
l
transformer itself.
The power cells of the drive contain several capacitors, which require a large precharge current when high voltage is applied.
l
MCB
HV~
Figure 12: Start-up Cabinet Circuit Diagram
FN41 Surge arrester (optional)
QF51 Circuit breaker
Install the start-up cabinet between the high-voltage power input and phase-shifting transformer. When the MCB of the drive is closed,
the start-up cabinet limits the magnetizing surge and charge current of the capacitance quickly and efficiently. After the drive is powered
up, the current passes through the KM51/QF51 bypass, and the drive can function normally.
Figure 13: Start-up Cabinet
Danfoss A/S © 2024.12
+PSTC
R
KM51/QF51
FN41
KM5
1
R
1
2
+PODU
Contactor
Resistance
3
4
5
6
7
8
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