Santerno DCREG2 Series User Manual page 111

DCREG2
DCREG4
EM: Electromagnet
L3
L2
L1
Otherwise, if you suppose that over voltage occurs only when the conduction mesh opens on mains side
(3-phase supply voltage L1-2-3 derived from sliding brushes), another protective measure exists.
On mains side, install an autotransformer (see Fig. 2) which ensures current flowing even if one or more
mains phases open.
To ensure the boost function (see below), voltage in the autotransformer secondary circuit should equal
1.5 ... 2 times the rated voltage of the electromagnet.
Apparent power of the autotransformer should be at least 50% stronger than DC power on electromagnet
side. If a real autotransformer is used (not an isolating transformer), voltage in the secondary circuit
should be at least 10 ... 20% weaker than voltage in the primary circuit, so as to avoid installing any
switching inductance.
L3
L2
L1
FU1-2-3: Ultrafast fuses
FU1-2-3
AT
AT: Autotransformer
L: Switching reactance
53
54
DCREG4
L3
L2
L1
L
1
4
FIG. 1
53
54
DCREG4
L3
L2
L1
FU1-2-3
EM: Electromagnet
FIG. 2
15P0059B3
USER MANUAL
FUC: Fuses 50A gG(gL)
EM
A1
A2
FUC
B1
B2
EM
A1
A2
FU1-2-3: Ultrafast fuses
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