Available voltage after failure with and without neutral shift
The following graph compares the available voltage after a failure with and without using
neutral shift. In many cases, the extra voltage available with neutral shift will determine whether
or not a cell failure can be tolerated.
2ULJLQDO1XPEHURI&HOOVSHU3KDVH
:LWKRXW1HXWUDO6KLIW
:LWK1HXWUDO6KLIW
3H
UF
HQ
WR
I2
ULJ
LQ
DO
9
RO
WD
JH
$Y
DL
OD
EO
H
DI
WH
U2
QH
)
DL
OX
UH
Figure 7-9
Available Voltage after a failure
The voltage capability of a drive after cell bypass can be calculated using the following
calculation:
If X is the largest number of cells in bypass in two of the phases, then the maximum voltage at
the drive output will be:
Vout_bypass = Vout * (2*N - X) / (2*N)
where:
Vout is maximum output voltage that the drive can deliver (Vout = 1.78*N*Vcell)
N is the number of ranks (i.e. number of installed cells = 3*N)
Vcell is the cell voltage rating
Example
For a drive with 18 cells, each rated for 690 V the maximum output voltage that this drive can
deliver is 7.37 kV:
Vout = 1.78 * 6 * 690 = 7.37 kV
With N = 6 and Vcell = 690 V
Operating the Control
7.4 Cell Bypass
Control Manual
190
Operating Manual, A5E50491925A
Summary of Contents for SINAMICS PERFECT HARMONY GH180
Page 2: ......
Page 22: ...Table of contents NXGPro Control Manual 20 Operating Manual A5E50491925A ...
Page 24: ...Security NXGPro Control Manual 22 Operating Manual A5E50491925A ...
Page 504: ...NEMA Table NXGPro Control Manual 502 Operating Manual A5E50491925A ...
Page 517: ...Index D NXGPro Control Manual Operating Manual A5E50491925A 515 ...
Page 518: ...Index NXGPro Control Manual 516 Operating Manual A5E50491925A ...
Page 530: ...Glossary NXGPro Control Manual 528 Operating Manual A5E50491925A ...
Page 537: ......